The Coastal Paleontologist... down under

Southern California Research Trip, Part 4: Page Museum at the La Brea tar pits

2012-01-29T19:13:00.027-07:00

After our last day of research at NHMLAC, Sarah, Morgan, and I drove to LAX to drop Morgan off for his flight back to the rockies. Sarah and I continued on, and had a two day trip planned ahead: first, we would visit the Page Museum of La Brea Discoveries in Hollywood, and then we'd drive north on Highway 1 from Santa Monica north through Malibu, Oxnard, Santa Barbara, Santa Maria, San Luis Obispo, Big Sur, and eventually through Monterey on our way back to the San Francisco area. We took a ton of great photos at the Page Museum which we arrived at just before opening; I've included some of the better and more informative photos here.

The front of the uniquely designed Page Museum. The museum is shaped like a square with a botanical garden courtyard, and above the museum, a large bas-relief is supported by that scaffolding.

A poor Columbian Mammoth is in deep... stuff.

My wife snapped this photo of tar bubbling up outside the museum. It's amazing how much tar is still seeping up. On my last visit in 2004, I didn't see anything around the park that was half this good; you can clearly see here the leaf litter and detritus that covers and camouflages the tar, while also seeing some obviously viscous, black, cartoon style tar bubbling up.

The famous Pit 91 excavation, which is temporarily on hold during the project 23 excavation a stone's throw away.

One of the panels from the bas relief above the museum, depicting a teratorn confronting a ground sloth.

A Columbian Mammoth skeleton, which I look way too happy to see (considering it's not marine, that is).

One of these things is not like the other ones...

My wife attempting to pull the plunger, showing how damned difficult it is.

The right canine is not the thing that's important in this shot, it's the left canine; although this is not a marine carnivoran, I'm interested in tooth eruption in carnivorans in general, and this made my day.

Skull and life restoration of Merriam's giant condor, Teratornis merriami. Still not as big as Pelagornis, but impressive and terrifying none the less.

Lots and lots of dire wolves (Canis dirus). This has to be my favorite display in the entire museum... it's beautifully constructed.

The spectacularly large and robust skeleton of the American Lion, Panthera atrox.

What? I thought this was the American Lion? Some recent studies have indicated the skull and mandibular morphology of Panthera atrox is more similar to the extant Jaguar (Panthera onca) than it is to African Lions (Panthera leo). There is a conflicting molecular study done with ancient DNA, however, but I'll save that for another time. Here's a question for any readers in the know: who the hell is Naegele? Joseph Leidy named the damn thing after all, so why isn't it named Leidy's Giant Jaguar?

A new American Lion specimen named "Fluffy" was recently excavated, and there was this temporary case which had in it what I thought was one of the better exhibits in the whole place: a three dimensional representation of the skeleton, using the same skeletal elements of a housecat. As a taphonomist, I particularly enjoyed this.

The bubble prep lab at the Page.

I love seeing stuff like this in prep labs. Apparently Arctodus is a patriot.

Is that a walrus in there? Damn, it's just a Smilodon. I really loved this display showing the three dimensional configuration of bones.

Smilodon again.

A bee outside the Page Museum. This has no relevance to the rest of the post, but it is a pretty picture, no?

A composite of two panoramic shots my wife took showing the bas relief.

A great shot taken by my wife of the wall of dire wolf skulls.

Hollywood!

Up next: Southern California Research Trip, Part 5 - detailing the Santa Barbara Museum, the coast, and the conclusion of the series of posts.

New artwork: reconstruction of a remingtonocetid whale

2012-01-27T07:16:00.002-07:00

Some time last fall I sat down and sketched out a drawing of Remingtonocetus, after Bajpai et al. (2011) was published. This new study described a new, nearly complete (and beautifully preserved) skull of Remingtonocetus harudiensis from India. The remingtonocetids are possible one of the only monophyletic groups of archaeocetes, and all appear to be relatively small-bodied, with ridiculously big heads and long rostra, very tiny and dorsally placed orbits, heterodont dentitions, and long tails. Perhaps the best way to imagine a remingtonocetid is to picture an otter with the (furry) head of a gharial.

The skull of Remingtonocetus harudiensis, from Bajpai et al. 2011.

The holotype skeleton of Kutchicetus minimus, from Bajpai and Thewissen (2000).

I had inadvertently sketched the head too small on the body, so when I completed the drawing over Christmas break with my wife's family in Montana, I ended up with a critter with a head that is way too small (although it looks like a less absurd beast, to be quite honest).

The original, unaltered drawing.

To fix this, I did some editing in photoshop after I had scanned the image - mostly by enlarging it's head about 20% or so. I also decided to experiment with texturing, and ended up with something that fairly convincingly looks like fur; I'm still experimenting with drawing fur in pencil, and as you can see between these two - the photoshopped version looks quite a bit better. Texturing can be pretty difficult on a small drawing - the original is only about 6" long from nose to tail. I was also able to make the wet fur on 'his' nose a little 'spikier'.

The modified version of the artwork. Overall, I'm quite satisfied with this piece, and am rather surprised that I was able to portray an archaeocete cetacean as "cute" - archaeocetes in general are pretty nasty, scary looking beasts, like Ambulocetus, Basilosaurus, Georgiacetus, and Dorudon.

The skull of Andrewsiphius, from Thewissen and Bajpai (2009).

There are a number of different remingtonocetids, including Remingtonocetus, Andrewsiphius, Kutchicetus, Attockicetus, and Dalanistes. Only Andrewsiphius and Remingtonocetus are known from good, well preserved crania. Bajpai et al. (2011) suggested that, based on the strange skull anatomy of Remingtonocetus, that remingtonocetids were ambush predators that were heavily reliant upon hearing rather than sight. The muscle attachment area is very large, and coupled with the very narrow jaws - suggests that remingtonocetids had a weak, but very fast bite, well suited for ambushing and catching small fish. Additionally, because Remingtonocetus was aquatic, the extremely long snout was probably not an adaptation for improved olfaction; Bajpai et al. (2011) hypothesize that as Remingtonocetus was one of the first marine cetaceans, this may have been an adaptation towards retention of freshwater during respiration.

Next up - continuation of the southern California research trip, Kolponomos, my Purisima vertebrate assemblage paper, desmatophocid taxonomy, etc.

Further reading:

A different kind of Whale, at Laelaps

Bajpai, S., and J.G.M. Thewissen. 2000. A new, dimunitive Eocene whale from Kachchh (Gujarat, India) and its implications for locomotor evolution of cetaceans. Current Science, 79(10):1478-1482.

Thewissen, J., & Bajpai, S. (2009). New Skeletal Material of Andrewsiphius and Kutchicetus, Two Eocene Cetaceans from India. Journal of Paleontology, 83 (5), 635-663.

Bajpai, S., Thewissen, J.G.M., and R.W. Conley. 2011. Cranial anatomy of Middle Eocene Remingtonocetus (Cetacea, Mammalia) from Kutch, India. Journal of Paleontology 85(4):703-718.

Southern California Research Trip, Part 3: Natural History Museum of Los Angeles County (collections)

2012-01-26T01:11:00.021-07:00

The purpose for our trip to visit the LACM collections was to examine a large collection of pinniped fossils housed there. Curator Emeritus Dr. "Larry" Barnes has been studying fossil pinnipeds since his master's thesis in the late 1960's (which he published in 1972, on Allodesmus and other desmatophocid pinnipeds), and has researched a wide variety of fossil pinnipeds including the early diverging and 'primitive' enaliarctines (a paraphyletic group of early pinnipeds), the relatively large and aberrant desmatophocids (an extinct group of phocoids known only from the North Pacific), all manners of fossil walruses, and fossil sea lions and fur seals. Larry has named quite a few fossil pinniped taxa from the northeastern Pacific region (Enaliarctos mitchelli, Pteronarctos goedertae, Pteronarctos piersoni, Pacificotaria hadromma, Desmatophoca brachycephala, Allodesmus gracilis, Proneotherium repenningi, Pelagiarctos thomasi, Gomphotaria pugnax, and Proterozetes ulysses), and there are a whole slew of holotype specimens to look at at the LACM - including a number of other important finds, including crania and jaws of the walrus Imagotaria downsi and the even earlier Neotherium mirum (but not quite as old as Proneotherium...). Our goal was to photograph all of these skulls and jaws, and take all sorts of measurements of them for our research. Between Morgan and I, we took about 5 gigabytes of photographs of these fossils. At the moment, we have two concurrent research projects which will soon be culminating in submittable manuscripts: a phylogenetic analysis of fossil and modern sea lions and fur seals (Otariidae; Morgan gave a talk on this at SVP this last fall), and another project describing some new material of the extinct "killer" walrus Pelagiarctos, originally described by Larry Barnes from the Sharktooth Hill Bonebed, and discovered by LACM head preparator and all around fun guy Howell Thomas. At bare minimum, we needed to examine, photograph, and measure the holotype "chin" and the referred teeth. Anything else we got done was a bonus - and our bonus included looking at dozens and dozens of skulls, jaws, and teeth of various other pinnipeds.

The hollywood hills can be seen very well from the prep lab, which is several floors up. You can just make out the hollywood sign below the top of the mountains.

The holotype "chin" of Pelagiarctos thomasi.

A referred lower left third or fourth premolar of Pelagiarctos, published by Barnes (1988).

My wife borrowed some of the clay we used for propping oddly shaped specimens up during photography and made a walrus and a manatee; the manatee even has
motorboat propeller scars (just for J. Velez-Juarbe!)

A referred lower jaw of Neotherium mirum from the Sharktooth Hill Bonebed, published by Barnes (1988); this is the only other early walrus from the middle Miocene bonebed.

My wife happened to find a book of 3D cat photos with 3D glasses. Don't ask.

Three different jaws of Allodesmus from the Round Mountain silt; but how many species? According to Barnes, there are three species: the topmost is the holotype of Allodesmus kelloggi, the middle is the holotype of Allodesmus kernensis, and the bottom one is Allodesmus gracilis. Others would lump all these in to Allodesmus kernensis (which would have taxonomic priority).

Three different early walruses! From left to right, they are Proneotherium repenningi from the Astoria Formation of Oregon (early Middle Miocene), Neotherium mirum from the Sharktooth Hill Bonebed of California (late Middle Miocene), and Imagotaria downsi from the Santa Margarita Sandstone (early Late Miocene) of Santa Cruz County, California.

The beautifully preserved holotype skull of Pacificotaria hadromma from the Astoria Formation of Oregon. According to Berta (1994), this may be a junior synonym of Pteronarctos.

Morgan and I conducting research amid a chaotic mess of fossil pinnipeds and other paleontological debris.

Downtown Los Angeles from the window in the prep lab. The US Bank tower can be seen in the middle. If you recall, it was blown to smithereens in Independence Day.

The rostrum and upper dentition of a referred snout of Desmatophoca oregonensis.

Morgan photographing the obscenely gigantic jaw of the bizarre double tusked behemoth of a walrus Gomphotaria pugnax. Seriously, that thing is offensively large.

The holotype skull of Allodesmus kelloggi, described by Ed Mitchell in the mid 1960's from the Sharktooth Hill Bonebed.

An undescribed late Pleistocene jaw of a California sea lion, Zalophus sp., from the Newport Bay mesa.

Last, but not least, another shot of those three walruses -
Proneotherium, Neotherium, and Imagotaria.

What's up next? One or two more posts on the southern CA trip including the Page Museum as well as the Santa Barbara Museum of Natural History, and eventually, I should probably try and cover some recent marine mammal research, I still have to cover a paper I got published on our wedding day, Kolponomos, and a bazillion other things.

Southern California Research Trip, Part 2: Natural History Museum of Los Angeles County (exhibits)

2012-01-23T00:07:00.018-07:00

After two and a half days at the San Diego MNH, Morgan, Sarah, and I said our goodbyes to our friends and colleagues there (Joe El Adli, Eric Ekdale, and Tom Demere), and piled into my tiny honda for the drive up to LA - we decided that spending another morning at SDNHM would allow us to drive up to LACM and miss all the morning traffic. We arrived at the museum at about 2 in the afternoon, and after chatting with Curator Emeritus Dr. Lawrence ('Larry') Barnes for a little bit, we got right to work examining fossil pinnipeds. I'll discuss the collections visit in the next post - first I'd like to talk a bit about the new mammal paleontology hall.

The new "Age of Mammals" hall has been in the works for several years, and has taken quite a bit of time on behalf of most of the Paleontology Dept. employees at LACM. I've seen a few photos on the internet prior to my visit, so I knew a little of what to expect. I don't have much of a research interest concerning terrestrial mammals - so, sorry terrestrial paleomammalogists who happen to be reading this blog (admittedly a very, very, very small fraction of humanity), but I'm going to ignore the land mammals. Some of the marine mammal highlights include a mounted skeleton of the sperm whale Aulophyseter morricei from the Sharktooth Hill Bonebed, as well as the holotype skeleton of the phocoid pinniped Allodesmus kelloggi (which, according to some, may be a junior synonym of Allodesmus kernensis), and adult and juvenile mounted skeletons of the late Miocene dugongid Dusisiren jordani, which were collected from the Santa Margarita Sandstone in Santa Cruz County. Lastly, and arguably the centerpiece of the marine mammal exhibits - is a beautiful new skeleton of Paleoparadoxia (which apparently may be named as a new genus in the near or distant future). Aside from these, there are a handful of skulls and pinniped fossils on display, including the world's oldest delphinid dolphin fossil - a complete skull from the Monterey Formation, unnamed and still undescribed. Overall, however - I must admit I was a bit underwhelmed. Certainly on the lower floor, there are plenty of fossil land mammals just packed in. But the top floor, which was an odd mix of La Brea specimens and marine mammals, there was just a lot of empty space, and there wasn't really that much marine mammal material on display, which is surprising given that the LACM holds one of the largest fossil marine mammal collections in North America.

Not in the Age of Mammals hall, but I had to include a picture of my favorite
pinniped, Callorhinus ursinus.

The juvenile skeleton of Aulophyseter morricei from the Sharktooth Hill Bonebed. This individual is under 50% adult size. The only known skeleton of this taxon.

This also was not taken in the Age of Mammals hall - but it goes to show that my wife likes to photobomb fossils all the time. I mostly put this up here to demonstrate to others that she is an awful person.

The holotype skeleton of Allodesmus kelloggi.

A cast of the holotype (and only known specimen) skull and jaw of the desmatophocid pinniped Atopotarus courseni. Atopotarus has occasionally been recombined as Allodesmus courseni, but desmatophocid taxonomy will have to be covered in a separate post.

A referred lower jaw of the Miocene sirenian Dioplotherium allisoni.

The adult female and juvenile skeletons of Dusisiren jordani from the Santa Margarita Sandstone in Santa Cruz County. The juvenile is so damn cute...

A Paleoparadoxia ulna with sharktooth bite marks. This specimen belongs to the mounted skeleton shown below.

A rather bizarrely portrayed fossil dolphin in some artwork related to sharktooth bite marks; I'm sure the artist was more interested and familiar with depicting sharks than cetaceans.

One of the exhibits I was looking forward to as a taphonomist - the gut contents of a Basilosaurus cetoides skeleton from Mississippi! It had as gut contents when it died
a mass of fish bones.

The articulated forelimb of the late Miocene delphinoid Albireo whistleri, originally described by Larry Barnes from the Almejas Formation at Cedros Island in Baja California.

The business end of the new Paleoparadoxia skeleton.

I'll leave you with this large size image of the Paleoparadoxia skeleton - my dslr camera doesn't have a wide angle lens, so I had to stitch these photos together for an ultra-size photo (I have a much larger version; contact me if you want it). And yes, that is the intrepid Morgan Churchill standing behind its ass.

Southern California Research Trip, Part 1: San Diego Museum of Natural History

2012-01-18T13:19:00.017-07:00

After a ten day visit with my wife's family for Christmas in Billings, Montana, my wife and I flew back to California, and had two days to get ready for a research trip to southern California with our friend and colleague Morgan Churchill. Except that we both got sick with a nasty two day cold - we got back on a thursday night around midnight, and were supposed to leave on sunday morning (which also happened to be January 1st). Needless to say, neither of us really were able to get ready for the trip on account of how crappy we both felt, and miraculously, waking up on sunday morning for the trip, I finally felt okay to drive, and the trip was a go (only we still had to pack, and didn't get out of town until close to 1pm). It's an 8 hour drive from San Francisco to San Diego (without traffic), so we were looking at a pretty late arrival. That being said, we had just driven up to Montana a couple weeks prior, and 8 hours seemed miniscule compared to two 10 hour days across the American west. We got to Los Angeles around 7pm, and stopped in for a couple hours to visit our best friend, Lee Hall, and his awesome girlfriend Ashley Fragomeni, which was refreshing (and far too brief). We finally pulled into east San Diego to pick up Morgan at about 12:30am (after driving through the densest coastal fog I've ever seen - and that's coming from a San Francisco native!). We pulled up to the house of our gracious host (and my coauthor) Joe El Adli, who also hosted me during the SATLW meeting in June at SDSU.

Morgan measuring a skull of Valenictus chulavistensis, the "toothless" walrus from the Pliocene San Diego Formation.

We had several goals for our visit - Morgan and I are studying a new specimen of the middle Miocene walrus Pelagiarctos, which Larry Barnes descibed in 1988 from the "chin" end of a pair of mandibles and some teeth, and suggested some interesting hypotheses regarding its paleoecology. At San Diego in particular, Morgan needed to spend some time photographing and measuring every pinniped skull and jaw he could (and it took up nearly the entire time of our visit). When not helping Morgan with measurements, I was chatting with Tom Demere (paleontology curator at the SDNHM) and Joe El Adli (lead preparator of the paleo department at SDNHM) about the fossil mysticete Herpetocetus, as well as photographing some earbones and crania of balaenopterids that occur in both the Purisima and San Diego Formations.

A mounted skeleton of Allodesmus (kernensis? gracilis? depends on who you talk to) at the SDNHM, while the tail and claspers of a giant Carcharocles megalodon loom ominously above.

A closeup of the business end of Allodesmus.

A skull of Desmatophoca oregonensis, a smaller and earlier relative of Allodesmus from the Astoria Formation of coastal Oregon. This specimen was collected by Douglas Emlong, and described by Tom Demere and Annalisa Berta in 2002.

Two pinniped skulls in particular that we definitely needed to see are on display in a huge cabinet out in the Fossil Mysteries hall. During my 2007 visit, I had been let into the cetacean display case to examine and photograph a porpoise skull, but that case actually had an entire door and you could walk around in it; this display case with the walruses had a 150 pound sheet of glass that required four of us (Morgan, Joe, myself, and the SDNHM collections manager, Kesler Randall) to use large suction cups to lift the ~7 foot tall sheet off of the case (which required Joe and Kesler to go up on ladders on either side). It was quite the performance, all done prior to the museum opening.

Joe (left) and Kesler (right) brainstorming about removing the sheet of glass from the walrus exhibit.

Joe placing the suction cups on the glass. The two walrus skulls in
question - Dusignathus seftoni on the left, and Valenictus chulavistensis on the
right - can be seen at the bottom of the case.

We needed to see two specimens in particular - one is the nearly complete and well preserved paratype skull of Valenictus chulavistensis, and the other is a referred skull of the dusignathine "double tusked" walrus Dusignathus seftoni. I had really ought to blog about each of these taxa, as they are truly wonderful and bizarre creatures. The new skull of Dusignathus was collected about 6 or 7 years after Tom Demere described and named the species in 1994, and is in much better shape than the holotype specimen, which is substantially smaller, and is missing the palate (although this new larger male specimen is missing the top of the skull). Although I've seen this display several times before, I must admit I was very surpised with 1) how small the Valenictus paratype is in comparison to other skulls, 2) how light the paratype is (Tom stated that it was very poorly mineralized and held together primarily with consolidant), and 3) how damn huge the Dusignathus skull is in comparison to other skulls in collections.

Joe (in brown) and Kesler (left) set the walrus crania down onto foam, while Morgan (right) and I (gray) watch.

While Morgan was taking photos, I decided to get a different angle on some of the fossils while I had a ladder available. Here I am shooting the Allodesmus photos seen above.

Here's a nice shot I got from the ladder of a new species of balaenopterid mysticete from the Pliocene San Diego Formation (this taxon is being studied by SDSU student Jessica Martin). So far as I can tell, I've not yet seen this animal from the Purisima Formation.

A neat mount of a fossilized wing of an albatross, Diomedea sp. (but should probably be identified as Phoebastria sp.). Albatrosses are definitely huge birds - but the partial humerus of Pelagornis sp. I recently published, which was only 1/2 complete, was the same length as the complete humerus of this specimen.

My wife always makes friends on research trips.

By the end of the San Diego visit, we had each taken several gigabytes of photos, and dozens of measurements for our research. My wife had spent a fair amount of time next door at the San Diego Zoo, and at the Museum of Man. We spent wednesday morning at the SDNHM to wrap up everything before driving to LA, where we would spend our first afternoon of research at the Natural History Museum of Los Angeles County (NHMLAC), but known to paleontologists simply as "LACM" - which will be the subject of the next post.

New USB microscope

2012-01-14T13:37:00.009-07:00

As previously mentioned, I've been using a USB powered microscope recently, which I purchased on Amazon for about 60 bucks. The Veho Discovery VMS 004 deluxe is tiny (a little larger than a cigar), and plugs right in to a USB port - I've already used it at UC Berkeley on a couple visits to photograph tiny vertebrate bones and teeth for a colleague. I had about 70-100 specimens I needed to photograph, all under 1cm in length, and using the microscope which was plugged in to my laptop, I was able to take photographs of all the cardinal anatomical directions in about three hours (~300 photos, so a rate of a minute per photo). Unlike a digital camera, the microscope immediately shows you if the picture turned out or not on a relatively large screen (digital photography has sped up picture taking so much that I occasionally get careless, and unintentionally let one or two photos out of every hundred get blurry and crappy, which is less of an issue with a larger display screen).

At Nick Gardner's request, I've posted some examples of USB photos I've taken. It's not the highest quality in terms of photography, and sometimes some of the images appear a little pixelated. Most of the time, the photos look okay, if not on the smaller end of publishable quality (i.e. smaller in terms of file size and resolution). Furthermore - don't buy this product if you're expecting continuous zooming, which they advertise that it has, but it really doesn't. It really only has two focal points, which is a problem. But then again, this thing is only 60 bucks, so you get what you paid for. All in all for the money I spent, I'm fairly satisfied as it effectively acts as a low-price, portable electronic dissecting scope. Lastly - the photos I've uploaded have not been modified in any way, so you can get an idea of what to expect.

Edit: I forgot I should add this in here - on the Amazon page for this item, there is a pretty lengthy review of the product by Paul Clifford, who has graciously written his own impromptu user manual for the microscope. He discusses some of the finer technical points a bit more technically than I have, and I'll admit I found his review very helpful when trying to experiment using this thing.

Most of these photos would not be high-resolution enough to be published at full page or even column width size - *but* would probably work well in a situation where you're figuring a number of small specimens all on the same figure.

An oral tooth of a wolf eel, Anarrhichthys sp. from the late Miocene Wilson Grove
Formation of Sonoma County.

A lateral tooth of a bat ray, Myliobatis sp., also from the Wilson Grove Formation. Yes, that is play-doh that Pat Holroyd gave me to photograph on; they don't like using clay at UCMP because it has nasty oil in it.

The apical view of the same Myliobatis sp. tooth.

Lastly, for all you cetaceaphiles, here is the stapes of UCMP 219111, a well preserved cranium of Herpetocetus bramblei from the Purisima Formation of Northern CA.

Up next - tales from my recent southern California museum collection visit with my wife and Morgan Churchill, to examine fossil pinnipeds at the San Diego Natural History Museum and the Natural History Museum of Los Angeles County.

Dead baby fur seals at the California Academy of Sciences

2012-01-07T09:00:00.000-07:00

Well, it’s been over a month since I’ve posted anything. It’s been a busy winter – in the mean time, my wife and I have celebrated Thanksgiving in California with my family, and have been in Montana for the last week with her family. I’ve been typing like a beast (30 pages for one manuscript just since I’ve been back in Big Sky country) over the last month or so. I’ve been working on my longest manuscript yet (not including my thesis, however it will soon overtake it), which as of this morning reached 110 pages. Additionally, we’ve been trying to get certain things ready for our imminent move to New Zealand. Just prior to Christmas vacation, I spent a couple of days visiting the Ornithology and Mammalogy collections at California Academy of Sciences.

A menagerie of bird and mammal skeletons and mounts.

A giraffe skull sits next to the sign in book.

A row of shelving filled with fur seal and sea lion skulls and skeletons.

A beautiful mounted skeleton of a sea otter (Enhydra lutris).

I’ve been making a couple visits per year to Cal Academy since 2006; I originally visited when the new building was under construction, and the academy (exhibits, departments, and all) were at the temporary storage facility in SoMa (South of Market in Downtown San Francisco, for the non Bay Areans) to check out their collection of Purisima Formation fossils, and to utilize their ichthyology and mammalogy collections to identify shark teeth and pinniped bones from various Miocene and Pliocene strata from Northern California.

A bunch of large mysticete vertebrae awaiting curation.

A pilot whale (Globicephala macrorhinchus) skull in the CAS collections.

On previous visits, I’ve searched the Mammalogy collection of skeletons to make comparisons with modern and fossil bones and teeth of fur seals, walruses, pilot whales, porpoises, and baleen whales. In 2010, I collected some (relatively basic) data on the variation of tooth root lobe morphology in northern fur seals (Callorhinus ursinus) for comparison with fossil fur seals, which I published in JVP earlier this year. A current project I am working on is writing up an entire marine vertebrate assemblage (~200-300 fossils), and I am working on a lengthy manuscript on the marine mammal compliment of the assemblage. Needless to say, the large and very well curated collection of marine mammal skeletons at California Academy of Sciences has been indispensable throughout this endeavor, and has made many fossil identifications possible and paved the way towards insights into marine mammal osteology.

Many crania and jaws of the Northern Elephant Seal (Mirounga angustirostris) are too large for storage boxes and sit right on the shelves.

A walrus (Odobenus rosmarus) skull with two baculi thrown in for good measure (no pun intended).

A bunch of boxes full of Galapagos Sea Lion skeletons (Zalophus californianus wollebaeki).

On my most recent visits, my objectives were threefold: first, to take photographs of many extant species of otariids (fur seals and sea lions) for a morphobank project with my colleague Morgan Churchill; second, to photograph nearly every skeletal element from an adult northern fur seal in order for comparison with fossil fur seals from California (e.g. Thalassoleon, which has previously been hypothesized to be closely related to Callorhinus); and third, to photograph and examine lower jaws of neonatal and fetal fur seals and sea lions.

Several drawers filled to the brim with boxes of small (fetal, neonatal, and juvenile) otariid skulls. Most of these are Callorhinus ursinus.

I won’t get into the specifics quite yet, nor will I talk about the fossils that spurred my curiosity regarding the third subject – I’ll only say that it is pretty damn neat if I may say so myself. That being said – I am very interested in the morphology of deciduous (milk) teeth in young fur seals, as well as the timing of molar and premolar eruption in the lower jaws of these animals. I’ll briefly mention that modern pinnipeds are a bit weird in that they (like most) mammals have milk teeth, but they are often shed before birth, so that the pups are born with a full set of adult chompers. Their milk teeth have a very reduced functional period, and additionally are reduced to tiny little pegs (unlike the milk teeth of terrestrial carnivores). Although they still develop milk teeth, pinnipeds are trending toward monophyodonty – that is, having only one set of teeth as opposed to two (diphyodonty). Cetaceans are monophyodont, and pinnipeds are an excellent example of a second clade of marine mammals following the same evolutionary trend.

A baby fur seal head (Callorhinus ursinus).

A neonatal Callorhinus ursinus skull in lateral view.

In order to examine the tiny milk and permanent teeth of these pups and fetuses, I brought along my new toy – a small, portable, USB powered digital microscope which plugs into my notebook laptop (…another new toy, which I’m using from a secure location in Montana). It displays the image on the screen, and can acts as a camera as well. Fortunately, there is a button to take a picture with in the software, rather than having to manually press a button on the microscope (which, due to its small size, usually jiggles it and screws up the picture). At an earlier UCMP visit in October, I was able to take around 200 photos of 100 tiny fossil specimens in a little over two hours. With the digital microscope, I was able to take a bunch of photos of milk and permanent teeth from nearly a dozen or so specimens of northern fur seal (Callorhinus), California sea lion (Zalophus), and Steller’s sea lion (Eumetopias). Unfortunately, there weren’t any northern fur seal fetuses, or specimens with deciduous premolars – but the data for sea lion fetuses I collected was more than sufficient to answer my fossil-related queries.

Yours truly using my digital USB microscope to examine the morphology of

fetal and neonate fur seal teeth; this specimen is a Northern Fur Seal (Callorhinus ursinus).

Milk teeth and unerupted adult teeth in the lower jaw of a California sea lion (Zalophus californianus) fetus.

Is Puijila a pinniped?

2012-01-02T22:55:00.011-07:00

Back in February 2009, Natalia Rybczynski and colleagues surprised the paleomammalogy community with their Nature paper naming a new genus and species of early pinniped, Puijila darwini. The holotype skeleton is relatively complete, and include fore- and hind-limbs along with much of the vertebral column, both jaws, and a well preserved skull. Puijila was about one meter long, and would have appeared relatively similar to a modern river otter. It had a short snout and a wide head, with large eyes and relatively high-crowned teeth. The teeth of Puijila still retain many of the cusps lost in modern pinnipeds, and also exhibit pits in the roof of the mouth for the lower teeth (embrasure pits). Unlike modern pinnipeds, it had a long tail, and did not have its fore- and hindlimbs modified into flippers. Puijila was discovered in 2007 from the Haughton Formation on Devon Island in Nunavut (formerly Northwest Territories in Canada). The Haughton Formation was deposited in an impact crater – the impact has been dated to 24-21 Ma (earliest Miocene), and fossil mammals from the Haughton Formation corroborate an early Miocene age. The Haughton Formation was deposited in an ancient lake that filled in the impact crater. In fact – if it were not for the impact, there would be no sedimentary rocks of Miocene age preserved that far North – all the young rocks have been eroded away by glaciation.

The skull and jaw of Puijila darwini, from Rybczynski et al. (2009).

The holotype skeleton of Puijila darwini (from http://nature.ca)

Previously, the earliest diverging pinniped (and arguably more derived than Puijila) is Enaliarctos, a fur seal sized pinniped from the latest Oligocene and early Miocene of California and Oregon. Enaliarctos retains carnassials, although many of the other dental features are very simplified and reduced, trending toward the condition in modern pinnipeds. Enaliarctos also exhibits limbs developed into flippers – and is very clearly a pinniped. But the relationships of Puijila – to pinnipeds and other carnivores – are not so clear. Because of the older age of Enaliarctos and its marine occurrence, Puijila is hypothesized to represent a lineage of early pinnipeds that stayed in their freshwater niche while marine pinnipeds like Enaliarctos evolved, remaining otterlike. It suggests that pinnipeds went through an otterlike freshwater stage before invading the ocean. Prior to this, Enaliarctos suggested a direct to saltwater invasion – although due to the absence of intermediates, it was not exactly clear one way or the other.

The skeleton and life restoration of Enaliarctos mealsi, from Berta et al. (1989).

Before we continue – I must also be specific about some clade names. Although Rybczynski et al. (2009) refer to Puijila as a member of the Pinnipedia – which is not really the traditional cladistic nomenclature for basal pinnipeds. Annalisa Berta and colleagues (1989) proposed the clade Pinnipedimorpha, for Enaliarctos and all later diverging pinnipeds. Berta (1994) later proposed the name Pinnipediformes for Pteronarctos and all later diverging pinnipeds. Pinnipedia is nested within Pinnipediformes, and Pinnipediformes within the Pinnipedimorpha. Within this traditionally accepted and utilized framework, Puijila’s obviously more primitive morphology than Enaliarctos indicates it should be referred to as a pinnipedimorph.

Rybczynski et al. (2009) listed six characteristics that unite Puijila with Enaliarctos and other pinnipeds. These are: a posteriorly expanded palate (the palate extends posteriorly past the upper toothrow in pinnipeds), an enlarged infraorbital foramen (occurring within pinnipeds due to larger whiskers and greater innervation of the snout), a shelf-like protocone on the upper fourth premolar (occurring in basal pinnipeds and some related arctoids), an upper second molar that is reduced and positioned medially to the upper first molar (reduction of the molariform teeth to conical teeth is a major dental transition within the pinnipedimorpha), a posterodorsally expanded scapula (a feature of pinnipeds, which often have very broad scapulae, an adaptation for swimming), and an expanded deltopectoral crest of the humerus (another feature in pinnipeds related to swimming).

Some of these features may be of only limited use in hypothesizing a close relationship between Puijila and pinnipeds. First, an enlarged infraorbital foramen (the small hole below the eye socket in a skull) also occurs in many mustelids, such as badgers (Taxidea), weasels (Mustela), and most (if not all) otters (e.g. Lontra, Enhydra); in badgers and weasels, this is due to a more innervated and sensitive snout, an adaptation for digging in burrows. This characteristic may not be useful in identifying early pinniped relatives, as otters (another hypothesized pinniped sister taxon) exhibit this feature – presumably evolving for the same purpose. The two postcranial features – an enlarged deltopectoral crest and a posterodorsally expanded scapula – may not be coded correctly in Puijila. To be quite honest, based on the available photographs – these features do not appear too different between Puijila and a river otter (Lontra), and don’t really exhibit the derived condition, which is much more extremely developed in Enaliarctos and other fossil and modern pinnipeds). This leaves only three reliable characters behind.

Skeletons of Enaliarctos (A), Puijila (C), and Lontra (D).

One of these features – a posteriorly expanded hard palate – also appears in the aberrant arctoid Kolponomos, as well as Pachycynodon and Allocyon (Tedford et al., 1994). This feature appears to be more widely distributed than previously admitted, although it is worth mentioning that it is probably an adaptation towards aquatic feeding. The two dental characteristics are probably more reliable, although it is odd to note that these two dental characteristics are also found in Kolponomos. Kolponomos will feature more in part two of this post, as it is both a fascinating creature which I have not yet properly covered on this blog, and it is also extremely topical to the subject of Puijila.

A wonderful reconstruction of Kolponomos by Ken Kirkland, published in Neptune's Ark by David Rains Wallance.

There are a whole host of pinniped characteristics that Puijila does not have, or features that were not described in enough detail to independently evaluate. Cranial and dental features that characterize pinnipeds (either at the level of the Pinnipedimorpha, Pinnipediformes, or Pinnipedia) include a reduced upper first molar, reduced cingulum on the upper first molar, an absent or reduced metaconid, loss of the embrasure pit between the upper fourth premolar and first molar, closely spaced mastoid and paroccipital processes, a reduced nasolabialis fossa, reduced cingulum on the upper third incisor, and a reduced trigonid cusp on the lower molars. None of these derived conditions appear to be present in Puijila. A number of postcranial features which characterize pinnipeds (either at the level of the Pinnipedimorpha, Pinnipediformes, or Pinnipedia, as above) include a short and robust humerus, enlarged tuberosities of the humerus, a flattened radius and ulna that are longer than the humerus, emphasis of certain digits in the hand and foot (i.e. largest digit in the hand being the first or “thumb”, and the lateral and medialmost digits of the foot being largest and the smallest being the middle digit), a short, flattened femur with an enlarged greater trochanter and medially inclined condyles, a reduced tail, and a short ilium (bone in the pelvis). Curiously, none of these features are present in Puijila – although nearly all of them (perhaps all – I can’t remember off the top of my head) occur in Enaliarctos.

In summary, there are very few features that actually unite Puijila and pinnipeds. The cladistic analysis of Rybczynski et al. (2009) was relatively limited, both in terms of the number of fossil and modern species used, and also with regard to the number of morphological characters used in the analysis. An earlier study – considered to be the landmark phylogenetic analysis of pinnipeds, Berta and Wyss (1994) – utilized 143 characters, while Rybczynski et al. (2009) only used 42. Granted, the earlier study focused on relationships within pinnipeds – and many of those characters may or may not apply to Puijila and other similar arctoids.

Because of the above, I am skeptical that Puijila has a close relationship with pinnipeds – and although I’m not convinced, I am equally receptive to the idea pending further analyses. There is much we’ve been waiting for – a detailed description of its anatomy and large, detailed figures of its skeleton were not included in the original study, which is understandable given the short length of Nature papers (however, it was not included as supplementary info either). There is certainly more work to be done, and there are rumors of a more detailed phylogenetic analysis in the works; such a study should include a comprehensive description of the skull and skeleton of Puijila accompanied by exhaustive figures (formerly difficult, but several modern journals have made this a far less difficult prospect), sample a broader variety of caniform carnivorans as well as more fossil and modern pinnipeds (fossil pinnipeds with postcranial skeletons such as Allodesmus, Thalassoleon, Leptophoca, Acrophoca, Piscophoca, Imagotaria, Neotherium, and Proneotherium) as well as the “beach bear” Kolponomos (which was not included in the original analysis or discussed by Rybczynski et al. 2009). Puijila certainly could belong to some group of otterlike “protopinnipeds” as hypothesized, but given the few characters uniting them, it very well could be some sort of mustelid or other aquatic carnivore.

October pinniped excavations

2011-12-27T13:52:00.011-07:00

Dick Hilton and I excavating a pair of fur seal (Thalassoleon) dentaries from the base of the cliff.

A famished yearling California Sea Lion on the beach.

The weekend before the annual meeting of the Society of Vertebrate Paleontology in Las Vegas, my wife and I joined Dick Hilton from Sierra College for what we assumed would be a routine visit to the Purisima Formation at Point Reyes. We drove up on a Friday night, and cooked hot dogs at the campground with Dick, and set up our tent for the weekend. The following morning, we set out along the shoreline, and within five minutes, found what appeared to be a pinniped skeleton. Since we wanted to get on to more prosperous localities further down, we left it there with the intention of digging it up the following day (Sunday).

My wife pointing to something tiny she is proud of finding...

It's a beautiful fur seal (Thalassoleon) molar! She has a real eye for finding things like tiny pinniped and shark teeth, which is why I keep her around.

Dick Hilton trying to explain something to my wife and I. At least I hope he was talking to my wife, because it sure looks like I wasn't paying attention.

As we headed further on down to the good section of shoreline, I found a well preserved porpoise earbone (petrosal), and a few other odds and ends. Not too long afterward, and nearly at the same time, Dick spotted a couple bones eroding out with an associated tooth, and my wife spotted a well preserved fur seal tooth (Thalassoleon), only a few meters away. It took us the better part of an hour to dig the bones up – which turned out to be a pair of associated fur seal dentaries! Unfortunately, neither specimen had any cheek teeth, but one did have a broken canine. Either way, only the middle chunk of the dentary is preserved in the holotype of Thalassoleon macnallyae (from the same locality), and these are the most complete and well preserved jaws of this taxon now known. We hiked down the beach a little further, and collected a couple of pinniped limb elements – a proximal end of a tibia, and a metatarsal. After collecting these, we headed back towards the cars. On our way back, I spotted a string of a dozen articulated pinniped vertebrae – a second skeleton we would have to excavate the following day.

A cast of the holotype skeleton of Parabalaenoptera baulinensis on display at the visitor center.

For comparison, there is also a skeleton of an adorably tiny (~15 feet long) minke whale (Balaenoptera acutorostrata) on display as well.

My wife examining some baleen (presumably from a balaenopterid) at the visitor center.

We also finally had a chance to visit the visitor’s center; previously, I had always been there on a weekday, when the center was closed. I was particularly excited to check it out because it has one of the only known casts of the holotype skeleton of Parabalaenoptera baulinensis (which was excavated from the Santa Cruz Mudstone at a nearby locality) on display – there is one other, but it is at the College of Marin in Kentfield, and is falling apart and badly needing repairs.

My wife decided she was done, and decided to spend the day reading A Game of Thrones on the beach and napping and taunting birds all day.

On the second day, we spent about seven hours excavating the first pinniped skeleton, which resulted in about 100 pounds of tin-foil jackets. This skeleton is probably of a large fur seal or small walrus, and the skeleton was completely disarticulated; as soon as we were close to removing one bone, another would be under it, or behind it. There were probably about two dozen or so bones in the cliff that we excavated. At about 4 in the afternoon, we wrapped up the first excavation, and walked down the beach to relocate the articulated skeleton. It took a while to relocate it, but as soon as we did, we started excavating it in a large block. Thanks to the specimen being articulated, we were able to finish this excavation in a little over an hour. Once we got back to the car, we loaded up nearly two hundred pounds of fossils we had collected in only two days in the field; furthermore, the most ridiculous aspect of the weekend was that by weight, cetacean fossils comprised less than 1% of our haul (only one specimen). For the uninitiated – pinniped fossils are relatively rare, and my master’s thesis sample of specimens indicates that there is a 4:1 ratio of cetacean fossils to pinnipeds, and that pinnipeds constitute only 8% of the marine vertebrate assemblage from the Purisima Formation at Santa Cruz. To collect a pair of associated dentaries, a tooth, a couple of associated hindlimb bones, and two skeletons (one being articulated) all in one weekend – is surprising, and tripled the number of major pinniped finds I’ve made. I’ll post some updates when some of this material gets prepared.

She nearly got this gull to come to her backpack. Sorry, no pictures of the pinniped excavation.

New mysticete excavation, part 3

2011-11-20T14:13:00.004-07:00

Hey Folks,

I already told the whole story of the excavation in the last two posts. However, if you'd like to see a recap of the whole dig, check out the animation I made below:

Enjoy!

New mysticete excavation, part 2

2011-11-15T18:19:00.012-07:00

On day two, we returned to continue the excavation process. We had mostly pedestaled the specimen on the first day, but we had not yet undercut the block. We thought we could get all of it out in one large jacket. Unfortunately, I knew this might be difficult because there were multiple fractures through the concretion - most concretions I've collected are very strong and have no cracks, but occasionally large ones are fractured, which could spell disaster during the jacketing process.

The skull on friday morning.

The tunnel I dug under the right side of the skull.

We got back to the locality on friday morning, and began to undercut the pedestal. Normally, a small jacket just requires a trench to be dug around the fossil, and then you undercut the bottom of the trench and dig under the fossil a bit - this allows a lip to be made on the bottom of the fossil with the plaster jacket, ensuring that the entire piece of rock (fossil included) leaves the excavation pit when you flip the jacket over. I've heard horror stories of jacket flipping where a stream of bone fragments pours out of the bottom of the jacket upon removal, and fortunately, this has never really happened to me. On larger specimens such as this, it is routine to dig a tunnel underneath part of it, to ensure that the jacket removes a cohesive block rather than half of it. So, I started doing this, digging from both sides, and after about an hour or so I had a cute tunnel underneath the skull where some strips of burlap could go when it came time to jacketing.

The fossil with dampened paper towel and after application of the jacket.

Late in the day on friday, we finally got to the jacketing process. In all honesty, I had not expected to get to start the jacket until saturday morning - we had scheduled a State Parks ranger to drive by on Sunday at 3pm for jacket pick up, so we knew we had until then. We finished up the plaster jacket right before dinner time.

The jacket right after flipping it.

On saturday morning, we quickly moved to undercut the rest of the jacket, "pop" it, and flip it over. This was particularly hairy, because there wasn't exactly any room to flip the jacket - usually you flip the jacket over, and have ample space to let it rotate along whatever surface you have available, which in paleontology fieldwork, is usually the ground. In our case, sure -we had opened up a large shelf we had dug out, but the fossil was already precariously positioned above a ten foot drop to the beach, more than enough distance for the fossil to break into many pieces if it were to fall. More importantly, if the jacket were to fall off the ledge, it would likely take one of us with it, which would really, really hurt. It would have really helped to have a third person, but we were barely able to lift and flip it between the two of us - we had to lift it and slowly rotate it nearly in place, move it to the side while lifting it, and while Des stayed there holding the jacket up from certain destruction, I ran up and down fetching pieces of wood to wedge it so it wouldn't fall off the ledge. During flipping, some of the fractures inside the concretion opened up, and we could feel the block 'flexing' a little bit. Fortunately, it all stayed together. Unfortunately, there were more bones going back into the cliff, which we will not be able to dig out. There was also a small part of the concretion and a possible bit of the skull left in the cliff, which we will have to return for.

The jacket after the bottom jacket was completed.

Wooden "backbone" for the sand ramp.

After flipping the jacket over, we were able to put on a plaster jacket over the bottom part of the block. Now that the jacket was completed, we had the problem of getting it down. The block appeared to weigh at least three hundred pounds, and was very heavy due to the concretion inside. There was no safe way to lift the skull down - the heaviest of a jacket that two people of my diminutive stature can manage is about 100 lbs (my friend Chris Pirrone and I once spent four hours moving a 100 lb jacket only 200 feet along a Santa Cruz cliff, while partially submerged at first, then up algae covered rocks, and along a 10 foot high, one foot wide ledge over the ocean, and up several eye-level ledges).

One thing I enjoy about paleontology fieldwork is thinking outside the box. I've had conversations with people who would have used some high-tech rope and pulley system which would have probably been a pain to put together and utilize. In my experience, when moving big (but manageable) pieces of rock, it's best to use methods developed by the masters of lugging around big rocks: the ancient Egyptians. Although it was up rather high, I thought "why not just build a big ramp?". To make it faster, we piled up a bunch of logs: sand usually moves to the angle of repose, and we needed something steeper (so we wouldn't end up with a cone of sand with a twenty foot wide imprint). The logs trapped the sand, and we were able to build a steeper ramp.

My wife with the beginning of the sand ramp, pretending it was her idea.

Des, myself, Ash Poust, and Liz Ferrer (clockwise, from upper left) start to
maneuver the block down the incline.

My wife (left, in red), Liz Ferrer (hiding in back), and Ash (white pants)
excavate a bit of the remaining concretion.

It only took us about a half hour to finish the ramp, and once we were done, we climbed up, and started to nudge the plaster jacket. Our friend Ash Poust, who was a friend of ours from MSU and now one of Kevin Padian's Ph.D. students at UC Berkeley, had brought along another one of Padian's students, Liz Ferrer, to help out. My wife sat out on this one, and took photos instead, while the rest of us muscled the jacket down. It worked like a charm, and I could not have been happier with my experiment in 'ancient methods'.

Stay tuned for the next installment!

New mysticete excavation, part 1

2011-10-12T20:14:00.011-06:00

Note: I feel like I've been doing this a lot recently, but sorry for the long lapse in posts. I just got back from SVP a week ago, and I've been sick during most of the intervening time. Before SVP, I was working like a fiend trying to get work done for a couple of presentations at SVP, and doing even more fieldwork in Marin County. I'll get some more blog work done now that things have calmed down.

Last August I had the fortune of excavating a Pliocene mysticete skull from one of my fossil localities in the Purisima Formation. I actually discovered this skull back in 2005, but had already found another that I preferred to excavate instead. I went ahead and excavated that other specimen instead, and left this one here. There were several reasons why I left this one alone. First, the other specimen was much closer to where we could park, whereas it was a mile walk to the skull featured below. Secondly, I only had the funds (and space in my small car) for one large plaster jacket, so this one had to wait.

The skull as it appeared prior to excavation, and in a basically identical
state at the time of discovery in 2005.

My permit for the locality was good for another year, so why didn't I collect it in 2006? Well, I was still preparing the 2005 whale (which I would be preparing for another four more years), and there wasn't lab space available for it. So my 2006 permit expired, and I didn't get another one until last fall. To be honest, I hadn't intended on collecting it this year either because I had no funding, no crew, and no vehicle to remove it with. One day a well known "personality" posted a question about fossil whales in concretions on the shores of some of the Channel Islands, and he was legitimately surprised by how many whales there are out there languishing, despite the number of able bodied vertebrate paleontologists in southern CA. I went on a bit of a rant and explained that it's the rule rather than the exception with regards to California fossil whales: there are uncollected bones and concretions littering Northern and Central California beaches, just asking to be put into a museum. I didn't think much of my email, until I got an email from Dr. Desmond Maxwell at University of the Pacific in Stockton, who explained that he had grown tired of taking his field crews all the way to Utah and Montana, and wanted some local prospects, and that he had plenty of funding, volunteers, and lab space for large marine mammal fossils. I gladly took him up on his offer, and this whale excavation was the "maiden voyage" of our field/lab collaboration.

The fossil, with estwing superpick for scale.

We arrived on the Thursday of the last week of August, with the intention of spending four days on the excavation. I met Des early in the morning at his hotel, and we drove out to the coast. The first day felt like two, both in terms of how much rock we went through and how long it was. The skull was in a concretion about ten feet up off the sand, and fortunately, had not been eroded at all since I found it in 2005 - at this locality, erosion is particularly slow, and the cliff erodes inch by inch, instead of being cut at the base and having blocks fall down, like at Capitola. Fossils that are over ten feet above the base of the cliff erode very slowly - a large baleen whale vertebra at another locality had the tip of its neural arch exposed in summer 2004, and as of October 2011, one half of the ventral side of the centrum is left (body of the vertebra).

Footholds cut into place for the excavation.

The first order of business was to cut footholds and ledges for us to stand on. Unlike the 2005 baleen whale excavation, the sandstone was very soft and friable; its height above the base of the cliff meant it spends more time out of the year being weathered and not waterlogged by high tides one half of the year. This made the excavation on the first day go remarkably fast.

Initial excavation of the skull, and cleaning of the exposed surfaces.

There were also several plants growing in the concretion, which we quickly plucked and removed. Fortunately, the roots did not penetrate the bone and destroy it, which has happened in some cases. After some early cleaning, it was apparent that the concretion was very thin over some parts of the skull, which would make life considerably easier than the previously excavated whale from this locality.

Des excavating the mysticete skull.

What exactly was it? It's convenient to just throw around the term 'whale' because it's huge, and you're not really quite sure. Well, initially I identified it as a right whale (balaenid), because I thought that the skull shape was consistent with that - wide braincase with a supraoccipital shield that did not extend very far forward. A few weeks later, I looked at more pictures of right whales, and I'm no longer too convinced my ID was accurate by any stretch of the imagination. Right whales have 'backswept' squamosals, and whatever this thing is, it's squamosals (it is sadly missing the lateral extremities of them) are relatively close to the vertex (top of the skull). More likely, it is a primitive balaenopterid with a short supraoccipital shield: the squamosals of balaenopterids are closer to the vertex than in balaenids, and are oriented laterally (not posterolaterally). Another possibility is that it could belong to a balaenopterid-like gray whale, which is known from the Pliocene San Diego Formation.

The skull after the first day of work. Not much appears obvious, but I'll talk more about it in the next installment.

Update: The coastal paleontologist gets married, and goes down under?

2011-10-09T12:32:00.006-06:00

The last couple of weeks have been pretty great, and due to being so busy in relation to recent events, I've been a little slow on posting new material on here. First and foremost, I got married to my longtime girlfriend/fiancee Sarah Michalies on September 17 up at beautiful Lake Tahoe, California. The wedding was fantastic, and a lot of fun - and there were many paleontology students from around North America in attendance. Sarah and I have been together since spring 2005, and it was about time to tie the knot. Sarah and I met as undergraduates in the paleontology program at Montana State University, and have gone on all sorts of paleo field trips together.

This is not our boat, we just borrowed it for cool pictures.

The second awesome thing that happened - I was recently (i.e. on Thursday) accepted into the Doctoral program at the University of Otago in New Zealand. I applied back in late July, and the plan is to start in January. I have the fantastic opportunity to work with Dr. R. Ewan Fordyce, who has offered me a chance to study eomysticetid fossils from the south island of New Zealand. Eomysticetids are a thus far poorly known group of early baleen whales, and constitute the earliest known and earliest diverging toothless baleen whales. So far, the only eomysticetids that have been described include Eomysticetus whitmorei and Eomysticetus carolinensis from the Oligocene of South Carolina, described by Larry Barnes and Al Sanders in 2002 in the Clayton Ray memorial volume. However, in that same volume, Barnes and Sanders name another new family of early diverging mysticetes they term the Micromysticetidae; they remove Cetotheriopsis tobieni from said genus and place it in the new genus Micromysticetus, to which they also name a new species from South Carolina, Cetotheriopsis rothauseni. This family also includes the taxon Cetotheriopsis lintianus. Anyway, Micromysticetus has almost always occurred as a sister taxon to Eomysticetus wherever included in phylogenetic analyses, and I would not be surprised if the Eomysticetidae were to include these even smaller taxa.

The holotype skull of Eomysticetus whitmorei from South Carolina (borrowed from the morphobank account for Ekdale et al., 2011).

The new material from New Zealand includes a collection of eight partial and complete crania, many with dentaries, earbones, and postcrania. In addition, two species of Mauicetus may be referable to the Eomysticetidae, and part of this project will revolve around trying to ascertain whether any of these new specimens represents referable material of Mauicetus; the skulls of the two holotypes of two Mauicetus species (not including Mauicetus parki, which is not an eomysticetid) are very incomplete or have been lost, but are still known from some earbones and postcrania (and photos of the skulls). One of my tasks will almost certainly be to determine whether or not any of this new material could be designated as a neotype specimen.

The clocktower at University of Otago.

All of that interesting paleocetaceanology aside, Sarah and I are going to New Zealand!!! We'll be living in the city of Dunedin on the south island. Above you can see a photo of the clock tower at the university; the campus there looks absolutely beautiful. Granted, Traphagen Hall at MSU Bozeman is a neat old building (but totally shitty inside), but I've seen photos of the Geology Building at OU, and it looks just like another Tudor stone castle like the main building pictured above. It looks totally awesome. Furthermore, unlike my previous 8 years of schooling in Montana, it doesn't get anywhere near as cold on the south island (although Dunedin is about as far south as you can get on the south island). And lastly, there are penguins that live there! There are penguins that have rookeries on the Otago Peninsula, within a 30 minute drive from campus! Blue/Fairy penguins, the smallest known species of penguin!

This is going to be a blast, and I have a lot of work to do to get there.

California shark teeth

2011-09-29T10:32:00.000-06:00

Yesterday while doing fieldwork at one of my research localities, I spotted a beautiful shark tooth poking out of the cliff. Only a very tiny part of the serrated tooth blade could be seen, and initially I was unsure of how large it was. After a few minutes of chiseling, it was clear that this was a rather large specimen of the great white shark, Carcharodon carcharias, and upon removal, ended up being about 3 cm long - the second largest specimen I had collected from this locality. This was a good day, as I generally have only found about 3-4 of these teeth per year; they are not too hard to spot - in fact, they are fairly obvious due to the easy-to see enamel and serrations (unless a root lobe is all that is exposed). Altogether, I have collected perhaps 50 Carcharodon teeth from the Purisima Formation in total - they are relatively rare in comparison to marine mammal bones. And this is not for lack of trying: I've found that it generally takes about 3-4 trips to a given locality before I spot another specimen; whether this is due to examining exposures not covered by the previous trip, or erosion between trips, I'm not sure.

The Carcharodon carcharias tooth as found in the outcrop.

The prepared specimen.

I've found that shark teeth are nearly impossible to find during the summer months, and easy to find in the winter, when the cliffs are cleaned off by surf action. I rarely find teeth in the summer simply because I tend to pick the localities clean in the winter, and I have to wait until the erosion of the following winter to find anything. Shark teeth are so rare in west coast strata that it is not very fruitful to look for them on nearby beaches; indeed, I found one Carcharodon tooth in this manner, in 2006 - and I have not found another this way.

Certainly, the Purisima Formation is not the only shark-tooth yielding unit on the west coast. Two rock units that boast a healthy dose of shark teeth are the Sharktooth Hill Bonebed in the Round Mountain Silt near Bakersfield, one of the highest concentrations of fossil shark teeth in the world - and the Santa Margarita Sandstone near Santa Cruz. At both of these localities, one can find dozens of teeth with little work (Sharktooth Hill) or quite a bit of digging (Santa Margarita Sandstone). In high school, I played hooky one day and drove down to Santa Cruz, and spent 8 hours in a pit with a shovel and my screen, and collected 70 teeth - but only after ending up with enough screened sediment to fill a Volkswagen beetle.

Fossil mako teeth (Cosmopolitodus hastalis and Cosmopolitodus planus) from the Sharktooth Hill Bonebed, UCMP Collections (image borrowed from http://www.ucmp.berkeley.edu/).

In 2005, I was fortunate to contrast my west coast experience with that of Calvert Cliffs. I had three hours to check out the famous Brownie's Beach, where just looking through shelly debris on the beach, I found 80 shark teeth (mostly the reef shark Carcharinus), just on the surface of the beach, in an area smaller than one side of a tennis court. I've seen mason jars filled with shark teeth folks have scooped up from Florida beaches, and seen multitudes of shark teeth from the famous Lee Creek mine in North Carolina. Sure, there is plenty of lore and mysticism surrounding east coast shark teeth (and their collectors in particular!), but I have gotten the distinct impression that most shark-bearing strata on the west coast are depauperate compared to that on the east coast. Contrast nearly 100 teeth per 3 hours of work to 30 hours of work for one tooth, for example. Additionally, although I have not personally collected data on this, the obscene number of shark teeth from certain east coast units (i.e. 24,000 shark teeth from Calvert Cliffs from just 3 years of donations to the Calvert Marine Museum; Visaggi and Godfrey 2010) suggests that the ratio of sharks:marine mammals in the east coast is astronomically higher than in the Purisima Formation (which in my thesis, I determined it to be around 1:40) and other west coast units. How could this be?

A heap of shark teeth from Florida (image borrowed from www.sharkysshop.com).

A number of biological and taphonomic hypotheses can be made:
1) The fossil shark assemblages perhaps differ in their taxonomic composition, and perhaps there is some related preservation bias.
2) The western Atlantic had higher productivity and stronger upwelling in the Neogene, supporting a larger absolute population of sharks.
3) Sharks and marine mammals have a different preservation potential, which a large-scale taphonomic process could act upon.

Immediately dismissing out of hand absurd suggestions like fossil marine vertebrates were preserved differently along either coast or had different skeletal mineralogy between ocean basins, one can start to think about the above suggestions. For example, contrasting the Carcharodon carcharias-dominated shark assemblage of the Purisima Formation with that of the Calvert Formation which is dominated by carchariniforms like Carcharinus, Hemipristis, and Galeocerdo, this suggestion seems to have some merit. However, there is little difference in preservation potential between these different types of sharks, aside from differences in size. In general, marine vertebrate assemblages in bonebeds and the like are very poorly sorted, and all shark teeth are relatively small in comparison, to say, a whale jaw.

The second suggestion has some merit: the old skeletal supply v. concentration idea discussed by Susan Kidwell back in her 1985 paper (although she was talking about mollusks). She argued that skeletal concentrations are usually caused by changes in sedimentation rate - a slowdown in the rate of sedimentation eliminates the diluting effect on bioclasts, allowing them to form a shell or bonebed (or even just a zone where they are slightly more abundant). Kidwell also argued that computer modelling she used demonstrated that her concentration model still worked even when the skeletal supply rate changed. Is it reasonable to assume that the populations of organisms have not changed through time? Of course not. Can we, from a uniformitarian standpoint, work with this in mind? Using Kidwell's model, perhaps - perhaps not. This being said, I'm not sure that more teeth = more sharks. This is a relatively simplistic view of the fossil record, and in the past, interpreting the paleoecology of fossil organisms has been fraught with problems (usually of the taphonomic kind). Sharks aren't the only organisms who would enjoy higher productivity - you'd expect marine mammals to be going bat-shit crazy with all the extra fish, krill, etc. to feed on as well (and eventually dying, shedding their hard parts onto the seafloor as well along with shark teeth).

The sedimentologic fossil concentration model proposed by Kidwell (1985).

What about the third suggestion? Sharks and marine mammals clearly have different skeletal anatomy, and although some elasmobranchs have been found with preserved skeletal elements (including skates from the Purisima Formation - stay tuned!), all that typically preserve are teeth, and occasionally, dermal denticles. Marine mammals have teeth, skulls, earbones, and postcrania that get preserved frequently. Teeth are harder than bones, and probably have a higher preservation potential with respect to purely physical taphonomic processes (i.e. abrasion from winnowing, erosion, and transport). In fact, my data from my master's thesis indicate that shark teeth are less commonly abraded or fragmented relative to marine mammal bones, and therefore it is probably kosher to say they have a higher preservation potential.

Okay, so what? There is clearly some differential preservation potential. But the Atlantic and Pacific oceans are big places: any specific sedimentological process (i.e. bonebed formation) is going to vary along hundreds of miles of the continental shelf, and through geologic time, and it may be difficult to pinpoint one single phenomenon responsible. In fact, to really examine this, we have to zoom way far out, to the basin level. What is the single most obvious difference between Neogene strata of the east coast and the west coast? Again we turn back to the work of Susan Kidwell (1993). In general, because the east coast is a passive continental margin, most of the strata (i.e. Calvert Fm., Pungo Ls., Yorktown Fm., Bone Valley Fm.) are deposited in low subsidence settings ('low' sensu Kidwell, 1993). Most of the strata on the west coast, including the Purisima Fm., are deposited in smaller basins undergoing "wrench" tectonics (i.e. pull-apart basins) or even rifting (Imperial Group, southern California), which Kidwell (1993) classified as medium-high subsidence basins; most basins in California probably qualify under this category (and could be determined via deposition 'rates' and basin thickness/depth).

The concept of supply versus concentration in Kidwell's model can be extrapolated to an entire basin: basin subsidence controls the sedimentation rate, and instead of looking at the microanatomy of a single shellbed, the types of fossil concentrations and their thicknesses and lateral extent can be compared between formations and basins. Just like a longer pause in sedimentation may form thicker shell bed, a formation deposited under lower rates of sedimentation will result in more numerous, thicker, and more architecturally complex shell concentrations. The Calvert Formation in particular was Kidwell's example of a low-subsidence setting. In general, Neogene marine strata of the west coast in general have less numerous and thinner shell concentrations, a general proxy for the sedimentation rate.

A taphonomic process of this magnitude can then be imparted upon a given example of differential preservation: at the end of this, the generally lower sedimentation rate of the western Atlantic resulted in higher amounts of taphonomic damage, more widespread and longer-duration hiatuses/bonebeds, and could have effectively acted as a taphonomic "wedge". By wedge, I am referring to the eventual difference in the preserved abundances of shark teeth and marine mammal bones. Marine mammal bones, with their relatively lower preservation potential, perhaps lost out due to their greater susceptibility to damage by abrasion and fragmentation.

References Cited

Kidwell, S. M. 1985. Paleobiological and sedimentological implications of fossil
concentrations. Nature 318:457-460.

Kidwell, S. M. 1993. Influence of subsidence on the anatomy of marine siliciclastic
sequences and on the distribution of shell and bone beds. Journal of the Geological
Society, London 150:165-167.

Visaggi, C.C. and S.J. Godfrey. 2010. Variation in Composition and Abundance of Miocene Shark Teeth from Calvert Cliffs, Maryland. Journal of Vertebrate Paleontology 30:1:26-35.

Getting material curated at UCMP

2011-09-27T02:09:00.000-06:00

On my last visit to UCMP, I spent an hour with a student volunteer and my good friend Ash Poust placing some material I had donated last year into specimen trays. These are all specimens collected from a locality in the Purisima Formation I studied as an undergraduate student. Most of this material was collected in 2005 and 2006, and I slowly curated and prepared it during my undergraduate career (and during grad school). I've now gotten about 1/2 of this collection to UCMP, and already it fills a drawer and a half.
Which is bad (and good). It's bad because the entire collection from this locality will take up half a cabinet by itself, not including the large oversize material. What's worse is that this material is roughly 1/3 of my entire collection - I have material I've collected from other Purisima localities, as well as the Santa Margarita Sandstone. All in all, my collection will probably require two-three cabinets at UCMP. Keep in mind I've already donated about 1/10 of my collection to the Santa Cruz Museum of Natural History.

Shark teeth and bird bones from the Purisima Formation.

That being said, it was a very satisfying experience to see all this material finally looking like it was part of a museum collection. I'm more motivated than ever to get the rest of it curated (and out of my house!). Now that I'm writing up the marine mammal assemblage from this locality, I can finally get rid of it all and get it into a proper museum setting.

Help preserve the Sharktooth Hill Bonebed

2011-09-13T19:15:00.004-06:00

Hey Folks,

This web page was posted several months ago, but to anyone who is interested, the Natural History Museum of Los Angeles County is trying to raise money to purchase the Sharktooth Hill locality for posterity.

To those unaware, the venerated Bob Ernst (who formerly owned the property) passed away several years ago. Unbeknownst to many, the vast collections at the Buena Vista Museum of Natural History made from Sharktooth Hill were not an actual museum collection, but Ernst's private collection on display, and passed on to his widow. When she began having financial problems, she began to sell and auction off the collection, including many specimens which have now been published in peer-reviewed articles (a big, big, BIG screw up on the part of certain researchers). This is really bad, because unless these specimens are donated to collections of real museums - that work is effectively rendered untestable.

That being said, here is the page, posted by Don Prothero and Teresa LaVelle:

http://www.skeptic.com/eskeptic/11-05-11/

A personal tour of the Sharktooth Hill locality will be given by the museum director, John Long, for donations of over 2000$.

Unfortunately, I'm still relatively poor, as a student, and anything I could scrounge together would barely amount to a drop in the bucket - however, I can help out by posting it here, and hoping that this message can get spread a little further. This is probably the most spectacular marine vertebrate fossil site in western North America, and so many problems could be solved for Mrs. Ernst and marine mammal paleontologists if this money were raised.

A new specimen of Parapontoporia

2011-09-05T19:46:00.014-06:00

Last fall I made a couple posts detailing an excavation (here and here) of a new odontocete skull from a relatively young (middle-late Pliocene) horizon in the Purisima Formation. This specimen was collected over a six hour period, and the excavation was pulled off and completed just before sunset. The specimen is still not completely prepared, but it does include a complete braincase, the posterior half of the rostrum, both petrotympanics (articulated petrosal and tympanics), and part of one of the lower jaws.

The new skull of Parapontoporia sternbergi in oblique dorsolateral view; bottom photo is labeled.

Three species of Parapontoporia have been described: Parapontoporia pacifica, from the late Miocene Almejas Formation in Baja California, Parapontoporia sternbergi, from the Pliocene San Diego Formation, the Mio-Pliocene San Mateo Formation, and possibly from the Pliocene Wilson Grove Formation, and of course, Parapontoporia wilsoni from the Mio-Pliocene Purisima Formation. Most of the Purisima material is referable to P. wilsoni, which is characterized by a very deep "basin" at the base of the rostrum (shown poorly in the photo below) and by a facial region that is longer than it is wide. P. sternbergi has a shallower basin, and has a facial region wider than it is long (and also appears to me to be smaller in general; P. wilsoni crania can be up to 20% larger than those of P. sternbergi). P. pacifica is not known from a complete braincase, and it has a flat base of the rostrum (i.e. no rostral basin). The new specimen exhibits a shallow rostral basin, and has a braincase that is wider than long, and is damn tiny - all suggesting that it is assignable to Parapontoporia sternbergi rather than P. wilsoni. "But the Purisima Fm. species is Parapontoporia wilsoni!", you might say. Just like modern cetaceans, fossil cetaceans likely had a cosmopolitan distribution - and Parapontoporia sternbergi is primarily known from late Pliocene rocks (specimens identified as P. sternbergi from Miocene strata should probably instead be called Parapontoporia sp.). The type locality of P. wilsoni is about 5.3 Ma, slightly older than the San Diego Fm. Likewise, the new specimen from the Purisima is from a horizon about 10 meters below an ash bed dated at 3.35 Ma, and therefore probably late Pliocene also.

Parapontoporia sternbergi, the most completely known species within Parapontoporia, exhibits an extremely elongate rostrum, filled with about 80 teeth per quadrant; that's a total of 320 teeth. I don't know the specifics for other toothy odontocetes (such as Eurhinodelphinids), but this strikes me as being a terrifyingly large number of teeth for a mammal, and I would not be surprised if Parapontoporia was the toothiest of all mammals. Additionally, the skull of parapontoporia is asymmetrical, unlike Pontoporia and more like the now extinct chinese river dolphin Lipotes. Parapontoporia was obviously named because it is closely related to the La Plata River Dolphin, Pontoporia, right? Right? Believe it or not, this new specimen weighs in on the phylogenetic relationships of Parapontoporia.

A reconstruction of a nearly complete skull from the San Diego Formation referred to Parapontoporia sternbergi by Barnes (1985).

The holotype of Parapontoporia wilsoni from the Purisima Formation.

When Larry Barnes published is major study of Parapontoporia in 1985 (the year I was born...), there were no skulls of Parapontoporia with associated earbones. Because of the similarity of Parapontoporia to modern river dolphins like Pontoporia and Lipotes, he looked through museum collections and tried to identify possible petrosals that could be referred to this new taxon. Oddly enough, one set of six petrosals from the San Diego Formation appeared very similar to modern Lipotes, although Barnes felt that the skull was more similar to Pontoporia.

Isolated petrosals from the San Diego Formation referred to Parapontoporia sternbergi by Barnes (1985).

Because of this discrepancy, there has been some disagreement (not in the published literature - in discussion only) about what the real petrosal of Parapontoporia looks like. At a UCMP visit once, Nick Pyenson showed me another petrosal which he felt might be a better match than the ones Barnes referred. This is a fairly serious matter, because these isolated petrosals have been used in various cladistic analyses to fill in the data matrix - and given the key phylogenetic position of Parapontoporia as a sister taxon to Delphinoidea - means that if the petrosals are not in fact from Parapontporia, there could be some serious errors in previously phylogenetic studies.

The petrotympanic complexes of the new Purisima Formation specimen of Parapontoporia sternbergi in dorsal/cerebral aspect.

The petrotympanic complexes in (near) ventral aspect.

This specimen is the first skull of Parapontoporia with well-preserved petrotympanic complexes associated with it. These petrosals are identical to those referred to this taxon by Barnes (1985), and confirm his referral. Interestingly, this also confirms the Lipotes-like morphology of the earbones. Previous cladistic analyses (e.g. Muizon 1988) have resulted in Parapontoporia being the sister taxon to Lipotes rather than Pontoporia, and several authors have suggested such a relationship, despite the hand-drawn cladogram and assertions of Barnes (1985). This new find indicates the Lipotes-like ear morphology does belong to Parapontoporia.

Petrosals of A) Inia, B) Pontoporia, and C) Lipotes.

Another Purisima Fm. skull of Parapontoporia wilsoni with a petrotympanic complex, in a private collection.

I'd be lying if I said that this were the first specimen ever found with petrosals and tympanics; two other specimens are known. One is a specimen of Parapontoporia pacifica from the Capistrano Formation at the San Diego Natural History Museum, which has a crushed tympanic and petrosal. The other specimen is also from the Purisima Formation, shown above, but has been unavailable for study. The petrosal is barely exposed and stuck within the concretion. This specimen remains in a private collection. This no longer bothers me, as the new specimen has both petrotympanics fully freed from the skull, and one of which has already been CT-scanned at UT Austin for a study by Manuel Martinez and Jonathan Geisler (among other authors, which I am dead last for this minor contribution). Look out for it at SVP!

References and further reading:

BARNES, L. G. 1984. Fossil odontocetes (Mammalia: Cetacea) from the Almejas Formation,
Isla Cedros, Mexico. Paleobios 42:1–46.

BARNES, L. G. 1985. Fossil pontoporiid dolphins (Mammalia: Cetacea) from the Pacific coast
of North America. Contributions in Science, Natural History Museum of Los Angeles
County 363:1–34.

FORDYCE, E., AND C. DE MUIZON. 2001. Evolutionary history of cetaceans: a review. Pages
169–233 in J. -M. Mazin and V. de Buffrenil, eds. Secondary adaptation of tetrapods to
life in water. Verlag Dr. Friedrich Pfeil, Munich, Germany.

GEISLER, J. H., AND A. E. SANDERS. 2003. Morphological evidence for the phylogeny of
Cetacea. Journal of Mammalian Evolution 10:23–129.

MUIZON, C. de. 1988. Les relations phylog`en´etiques des Delphinida (Cetacea, Mammalia).
Annales de Paleontologie 74:159–227.

PYENSON, N. D. 2009. Requiem for Lipotes. Marine Mammal Science 25:714-724.

Recent fieldwork in the Purisima Formation, Part 3: mysticete earbones and wildlife

2011-09-01T16:02:00.005-06:00

Hey Folks,

Sorry for yet another delay - I've been pretty busy, working on several manuscripts (a thesis-length paper on the Purisima Formation marine mammals from my undergraduate field area in Halfmoon Bay, a new manuscript on shark bitten cetacean bones, and my contribution to a paper of the mollusk and vertebrate assemblage of a late Miocene marine locality in Sonoma County), applying to the University of Otago Doctoral Program to work with R. Ewan Fordyce (in New Zealand), and digging up a new right whale fossil from the Purisima Formation. There are plenty of topics I have thought of to write about on here, but not enough time!

Continuing on with my series of posts about recent Purisima Fm. fieldwork with Dick Hilton, I've written a little about a new mysticete earbone. There are lots of mysticete earbones from the Purisima Fm., from number of different taxa, including cetotheriids, many balaenopterids, and balaenids. Dick had originally spotted this specimen during a field trip earlier in the spring, but was unable to collect it. On our first day of our expedition back in late May, we spotted it easily, and given the easier tides, we were able to quickly excavate it. I was immediately struck with the size of the specimen, and in particular a large knob called the dorsal posterior prominence. This very distinctive earbone morphology is characteristic of the extinct rorqual "Megaptera" miocaena, which Remington Kellogg described in the 1920's from the late Miocene Sisquoc Formation of southern California. Several authors including Deméré et al. (2005) and Dooley et al. (2004) have suggested that it does not belong in Megaptera at all, and that it requires a new genus to be erected. However, it has appeared in some phylogenetic analyses (Bisconti, 2008; Marx, 2010) as a sister taxon to modern Megaptera novaeangliae (the modern Humpback Whale for the uninitiated). It really needs to be reanalyzed and probably redescribed.

Fossil tympanics of "Megaptera" miocaena from the upper Miocene San Mateo Formation (left) and Purisima Formation (right).

Fossils of this taxon are now known from Tortonian and Messinian (6-11 Million Years Old) strata in California, including the Sisquoc Formation, Purisima Formation (two localities), and the Santa Margarita Sandstone (a new specimen of which will soon be donated to UCMP). Other vertebrates from this time period include the dusignathine walruses Pontolis and Gomphotaria, the odontocetes Denebola, Parapontoporia, Albireo, and Piscolithax, as well as other mysticetes such as Nannocetus and Herpetocetus; all of these taxa are now known from multiple strata of this age, suggesting a distinct, and well-represented late Miocene marine mammal fauna from the eastern North Pacific.

Lastly, we spotted some wildlife during the trip, the photos of which are below.

Northern elephant seals spotted from the point.

A peregrine falcon near a nest at the edge of a cliff.

A coyote that ran along the beach while we stopped for a snack.

References:

Bisconti, M. 2008. Morphology and phylogenetic relationships of a new eschrichtiid genus (Cetacea: Mysticeti) from the Early Pliocene of northern Italy. Biol J Linn Soc 153: 161–186.

Deméré, T.A., A. Berta, and M.R. McGowan. 2005. The taxonomic and evolutionary history of fossil and modern balaenopteroid mysticetes. Journal of Mammalian Evolution 12:99–143.

Dooley, A. C., Jr., Fraser, N. C., and Luo, Z.-X. 2004. The earliest known member of the rorqual-gray whale clade (Mammalia, Cetacea). J. Vertebr. Paleontol. 24: 453–463.

Kellogg, R. 1922. Description of the skull of Megaptera miocaena, a fossil humpback whale from the Miocene diatomaceous earth of Lompoc, California. Proc. US Natl. Mus. 61: 1–18.

Marx, F. G. 2010. The more the merrier? A large cladistic analysis of mysticetes,
and comments on the transition from teeth to baleen. J Mammal Evol 18:
77–100.

Recent fieldwork in the Purisima Formation, Part 2: a possible new species of Herpetocetus?

2011-08-09T03:03:00.011-06:00

Back in late May, Dick Hilton (Sierra College) and I did a three day field trip collecting fossil vertebrates from a locality in the Purisima Formation I recently got a permit for. On the second day, excavated a large block of sediment with what I assumed at the time were sirenian bones. I had not seen the bones except in cross section, and because they were somewhat dense, I thought they might be from a sea cow. We quickly carved out a large block, and due to the cohesive nature of the sediment, we were able to wrap it in tinfoil and duct tape. It was one of the first finds of the day, and I thought there could definitely be something neat inside. Because we were only a half mile from the cars, I left my pack with Dick and hoofed it back to the car with the thirty pound block, and also to grab some gatorade I had left in my car. When I returned, Dick was taking a siesta, and after some lunch, we headed further down the beach. Only a few hundred feet down I spotted a distinctly potato-shaped thing sticking out next to a piece of bone: it rather looked to me like a tympanic bulla, and I climbed up a bit to check it out. It was in fact a tympanic, and when the rest of the piece came out, I was able to see that it was in fact a nearly complete squamosal, complete with the bulla and posterior process of the petrosal. Dick and I thought the trip had been a success just because of this specimen, especially because it was from a section of cliffs where neither of us expected to find anything.

Dick Hilton digging up a huge baleen whale tympanic.

I couldn't have been more wrong. Unfortunately, I didn't know that I was until after the SATLW (Aquatic Tetrapods) conference. I did have a day or two before the conference to prepare the squamosal, and it did indeed have a plug-shaped posterior process of the petrosal, indicating it belonged to the Herpetocetinae, which includes Herpetocetus, Nannocetus, (probably) Piscobalaena, and Cephalotropis (according to Steeman, 2007). After the conference, I opened up the duct taped jacket and began preparation. After a couple hours the exposed pieces were still not making sense, and then I found a couple of bones that looked like they were adjacent to one another. When I removed them, there was a tiny neck of bone connecting them – and after a little more preparation, I realized it was a Herpetocetus petrosal and posterior process. Damnit, another goddamn Herpetocetus.

The petrosal and posterior process of the new specimen, with the facial nerve canal labeled. Upper left is ventral, lower left is dorsal, and right is medial view.

The skull with (partially incorrectly) articulated petrosal of the new skull in dorsal (top) and ventral (bottom) views.

Once I had enough of the block prepared, I realized I had quite a bit of the ventral portion of a small braincase preserved. It includes both exoccipitals, one occipital condyle, the basioccipital, the right squamosal, and the complete petrosal. After preparation, the petrosal is most similar to petrosals of Herpetocetus. This may be a bit technical, but herpetocetine baleen whales have several peculiar features that define them as a group. The posterior process of the petrosal – which is typically an elongate strap of bone that connects with the skull posteriorly – is very short and plug-shaped in these animals. Additionally, the posterior process (which is rarely found attached in isolated fossil mysticete petrosals) is flat and contributes to the lateral side of the skull, instead of being 'hidden' in a trench between the squamosal and exoccipital bones. Secondly, some herpetocetines have a flattened anterior process that is blade shaped; this structure is typically conical and robust or knoblike in most other mysticetes. Clearly, this specimen exhibits both of these features. Additionally, Herpetocetus spp. exhibit a large triangular flange on the side of the bone, which overhangs the squamosal – also present in this specimen. Additionally, herpetocetines all have extremely small earbones relative to most mysticetes. Unfortunately, the neck of the posterior process appears to have been deformed slightly, and when the main portion is articulated correctly, the posterior process sits in its trough a little wonky, and when the posterior process is articulated correctly, the main portion doesn't articulate well.

The posterior process, squamosal, and tympanic of Herpetocetus bramblei.

The two alternate articulations of the petrosal showing correct articulation of the posterior process (left) and correct articulation of the body of the petrosal (right).

The temporal region of the skull of Herpetocetus bramblei with the petrosal outlined in red.

However – it shows several features that differentiate it from all species of Herpetocetus as well as other herpetocetines like Nannocetus and Piscobalaena. Firstly, the anterior process is medially oriented – it is usually anteriorly facing instead. Second, the posterior process is very transversely narrow and elongate – it is typically more nearly circular in other species. Lastly, the most bizarre feature is that it has a very long anterior fissure of the facial nerve canal which is contorted into an S-shape – something I have not seen in any mysticete, fossil or modern.

Various mysticete petrosals in ventral view, showing two fossil rorquals (Plesiobalaenoptera and Balaenoptera sursiplana), a modern balaenid (Eubalaena japonica), the new specimen, and two other Herpetocetus specimens.

This is pretty exciting, and I am looking forward to preparing the other specimen, which includes part of a squamosal and a tympanic, and most likely a petrosal. It should not be too difficult to get these specimens written up and described.

Recent fieldwork in the Purisima Formation, Part 1: Gigantor whale jaw

2011-08-07T16:21:00.008-06:00

If you pay attention to paleo-related news on the intertubes, you may have seen a recent article about a 700 lb dinosaur bone excavated from the Morrison Formation near Fruita, Colorado. Fellow MSU student Krista Brundridge was even interviewed and involved in the excavation. They only state that the bone is from the animal's back, so I can only assume that it's a huge sauropod vertebra. Which means that maybe the kind folks over at SV-POW! will be drooling over the news. If people really wanted to dig up humongously sized plaster jackets, they'd come to California and dig up whales. Why, back in may, Dick Hilton and I prospected a locality in the Purisima that hasn't been collected by paleontologists in over twenty years, and over the course of two days, found dozens of multi-ton blocks just sitting there on the beach. Many of them had vertebrae (which unlike those of sauropods, are much more conservative in their anatomy), ribs, and other odds and ends. However, I counted many that had skulls. One block that was the size of a pickup truck had a complete skull, at least one lower jaw, and apparently part of an articulated vertebral column and ribcage.

Me posing with half of a gigantic whale jaw.

Wait a second, you say. Dinosaur paleontologists scrounge up every scrap of bone, and re-re-describe old fossils (i.e. Dryptosaurus was first described, then re-described, and then re-re-described), and bitch and moan about there not being enough material for new researchers. How would complete skulls of baleen whales just sit on the beach without some intrepid explorer to come along and excavate or collect them? Below, I've got a photo of what used to be a complete baleen whale jaw sitting in a large boulder, ~20 feet above the beach. I climbed up to it, which was pretty hairy – usually the Purisima Formation is sandstone, and easy to carve handholds in, but this was nasty hard fractured mudrock. This jaw must be in a concretion that weighs the same as my small Honda. For baleen whales, jaws are "relatively" diagnostic (see here, here, and Boessenecker 2011), so specimens like this are of interest. Baleen whale skulls are of course diagnostic, and it is unfortunate that they are languishing like this.

It was kind of a pain to get down from there.

One problem, you might say, is that they're big, and in very tough rock. Yes, I spent five years of my life (intermittently) preparing a mysticete skull in a concretion that I collected from the Purisima Formation. Sure, it's a big heavy skull, but surely smaller and less heavy than any ceratopsid skull you can point at. Obviously, blue whales have bigger crania than dinosaurs like Triceratops. Most fossil mysticetes have skulls that are smaller than or roughly the same length as the largest "Torosaurus" skulls, but many museums out there don't hesitate to go dig up more Triceratops skulls. Is it the often concretionary matrix and the time-intensive nature of the preparation that makes whale fossils "unpopular"? I don't think so, because I can't count the number of dinosaur bones (even undiagnostic material like ribs) encased in hard rock being prepared.

Permanently borrowed from SV-POW! Thanks guys, this image is awesome.

Are whales and whale fossils just unpopular within vertebrate paleontology? Maybe. Given how whales captivate the imagination – mind you, not in the gory, Velociraptor-chasing-kids-through-a-kitchen and lawyer-eating sort of way but the holy-shit-its-a-brachiosaurus-on-a-grassy-hill sort of way – I highly doubt that cetaceans lack the cool-factor. They may not have big sharp pointy teeth... oh shit, I forgot that fossil sperm whales are far more impressive than any puny theropod. Sorry, Livyatan beats T. rex. I think the real problem is that we have the Jurassic Park generation in vertebrate paloentology now – and not to sound like a bitchy hipster, although I am of the correct age group – I was into paleontology before Jurassic Park came out.

Nevermind that in the background.

Perhaps this is a problem that is, within the United States, unique to Northern and Central California. Southern California fossil cetaceans are really well taken care of, and get excavated and pampered at places like LACM, the Cooper Center, and the San Diego Natural History Museum. The extremely rich Calvert Cliffs and other Mio-Pliocene units of the Chesapeake Group of the mid Atlantic coastal plain are covered by the Calvert Marine Museum, the Smithsonian, and my dear friend Butch Dooley at the Virginia Museum of Natural History. Florida fossils are generally covered by the FLMNH and the University of Florida. The comparatively rich fossil record in the Oligocene and Miocene of Washington State (and parts of Oregon as well) are covered by the Burke Museum in Seattle. However, all of the UCMP students who collected a ton of material from Northern California in the 1970's and early 1980's moved on elsewhere.

I don't mean to complain – having a surplus of fossils available for my research is nothing to complain about. However, it is depressing if not distressing to see so many fossils I could not collect, prepare, and study alone in five or six lifetimes, just sitting out there on the beach. So: to all of you dinosaur folks who feel perhaps the field is a little too crowded, too much of a circlejerk, or whatever, come join marine mammal paleontology! Trust me, there are is a large hoard of new genera and species out there just waiting for the taxonomically hungry. In five years of serious collecting, I've got enough material to research for another ten years, and this is barely scraping the surface. So, this is a call for action! If you're interested in marine mammal paleontology, go dig up a whale (instead of Apatosaurus #32, or NewGenusOfUninterestingChineseDinoBird #54, or re-re-redescribing something everyone is already familiar with) or find someone who can help you (...or me, for that matter).

Unfortunately, the sad reality is that that jaw I posted above will probably not be collected. I don't have the funding, resources, or the connections (read: friends with heavy machinery) to collect stuff like that now. To be honest, it isn't complete enough for it to be worth it anyway. But that's besides the point: it was at one point, and another one will come along that will be worth collecting. Will we be up to the challenge?

Sorry for the rambling here, the rest of these posts will be about fieldwork I did with Dick Hilton in May, I promise!

Preparing an auk bone from the Purisima Formation, part 2

2011-07-31T02:43:00.000-06:00

In order to properly prepare this bird bone (see previous post) , I decided to pour two part epoxy onto the eroded surface of the bone. In the field, I carved a block out of the rock with the bird bone in it, and wrapped it in tin foil. Weeks later, I unwrapped it and began the preparation process.

Beginning steps of preparation. A - the collected block prior to preparation. B - supplies needed. C - application of vinac using a paintbrush. D - application of thin superglue to stabilize parts of the bone.

First off, the bone had to be stabilized. Vinac and Butvar are two acetone-based consolidant glues which are very thin (i.e. have a low viscosity) and soak into porous bone well. In this case, I was not satisfied with vinac alone, so I began by dripping superglue into the most poorly preserved parts of the bone; superglue is also thin enough for this task, although it is substantially more difficult to reverse if you screw something up. I followed this by a liberal application of vinac onto the bone. I also painted vinac onto the sandstone where I would later pour epoxy. I did not want the outermost layer of the sandstone to flake off of the cured epoxy and take the bone with it, or alternatively, have only part of the bone stick onto the epoxy plate and the rest fragment off.

Epoxy application onto the fossil. A - a rolled up cylinder of paper serves as a convenient and cheap tool to drip epoxy with (as opposed to popsicle sticks or tongue depressors). B and C - the rolled up paper tube is used to drip epoxy. D - the epoxy sheet is allowed to cure overnight.

Part two of the preparation process was to apply a generous layer of epoxy, once the vinac had cured. Two part epoxy comes in paired tubes, and has to be mixed - I usually just mix it onto a piece of scratch paper. I tear off one side, and roll it up to use as a "honey dripper" (you know, like the thing you see in honey nut cheerios commercials and cereal boxes) to collect and drip epoxy from. It is imperative to try and mix it 1-1 - it can be difficult, because sometimes pushing on the plunger results in one tube being pushed more than the other, and you get something more like 1.3-1, which will take longer to cure and may not cure ever, which is a really bad problem if you're working on an important specimen. Don't screw that up. Sometimes, there is also more of a bubble in one tube, making one of the component parts come out more than the other; you can mitigate this by pushing back on the sides of the plunger, making the other tube extrude more epoxy (maybe I should do a post on beginner epoxy tips).

A second coat of epoxy was applied along the bone in order to strengthen it, and
was allowed several days to cure. Once it was cured, the soft sandstone matrix was wetted for easy removal, and the block was picked away and carved down to size.

The initial coat came out sort of thin in places, which I thought would be too flimsy. I decided to mix some more epoxy and add a second, thicker coat right up along the bone. The first coat was still sticky to touch even after 24 hours, so after I added this second coat, I allowed it to cure for about four or five days while my fiance and I went on vacation. When we returned, I soaked the sandstone block in warm water and allowed the sandstone to become saturated; Purisima Formation sediment is much easier to prepare and separates from bone much more easily when wet - I estimate it makes preparation take 2/3 to 1/2 less time than it would if the sandstone were dry. The block was carved down to a size roughly equal with the epoxy plate.

Preparation of the sandstone off of the bone and epoxy plate. A - one centimeter of sandstone left. B - a small bit of the ventral tubercle (a small dark spot of bone down and to the left of the 'B') is exposed. C - it doesn't take more than another ten minutes to expose nearly the entire proximal end of the bone. D - after some more work with a dental pick and a wet toothbrush, the preparation is finished. E - the finished product, after vinac application.

The above picture shows the progress of preparation. The final product shows the important bits of the cranial/anterior surface of the bone. Additionally, where the middle of the shaft had broken away it left a slight mold that more or less shows the shape and curvature of the shaft - the epoxy filled in this as a small cast, and the original shape of the bone can be seen. The only unfortunate thing about this is that the mancalline "scar" that allows identification of various species is not really accessible - it is probably preserved, and the pneumatic foramen is filled in with sediment; preparation of this would require removal of some of the epoxy around the ventral tubercle. It does, however, preserve a slight muscle attachment crest on the bicipital crest, which suggests this specimen may belong to Mancalla lucasi as well. Either way, this specimen indicates that this part of the Purisima is Pliocene in age.

Preparing an auk bone from the Purisima Formation, part 1

2011-07-30T15:38:00.011-06:00

I know I had promised another post on pelagornithids (and sooner than this), but I just finished a preparation project on a small bird bone, and I think it is too cool not to share the method I used for this. Dick Hilton and I were recently doing some fieldwork together in the Purisima Formation, and I jumped up on a ledge and found a bird humerus exposed in a horizontal exposure.Dick Hilton near a new baleen whale find in the Purisima Formation.

The new bird bone, not entirely unsalvageable.

As soon as I saw it, I thought it was unfortunate that so much was missing; nearly the entire caudal/posterior face was missing, and eroded parallel to the long axis of the bone. Additionally, the middle of the bone was completely gone; enough of each end were missing that it would be very difficult to collect each end separately and not have them fragment into a million pieces during preparation. Bird bones are not exactly rare in the Purisima Formation, but since the length of bird bones has historically been used as a taxonomic tool along with other morphologic features, I thought it better to excavate it as a block - and to be honest, nearly the moment I saw it, the gears were already turning and quickly formulated a preparation solution.

The new fossil specimen compared with a more complete humerus of Mancalla lucasi (formerly Mancalla diegensis). The cross-hatched area indicates what was missing of the new specimen.

Additionally, the curvature of the shaft and the distinctive proximal end (even in cross section) made the bone very easy to identify - it is transversely flattened and curved, which identifies it as the flightless auk Mancalla; this bird happens to be the most common bird taxon in the Purisima Formation - auks and puffins (Alcidae) happen to be relatively common in general. In a forthcoming paper, I describe a fossil humerus identifiable as the species Mancalla diegensis; in a recent paper on mancalline auks, my colleague (and coauthor on the Pelagornis article) Adam Smith sunk Mancalla diegensis and erected a new taxon, Mancalla lucasi (I have another post lined up summarizing mancallines and Smith's new monograph). This specimen is very similar to Mancalla diegensis in terms of size, but could just as easily belong to Mancalla cedrosensis, Mancalla calforniensis, or Mancalla vegrandis.

I thought an easy way to deal with this specimen would be to liberally apply a large sheet of two-part epoxy onto the exposed broken surface of the bone and sediment, and prepare it down from the other side. This I hoped would result in a sheet of plastic with the caudal surface of the bone exposed on the other side. The next post will describe the preparation process, and hopefully give you ideas on how to tackle similar problems when dealing with fragmentary fossils.

A bony toothed bird from the Purisima Formation, part 2

2011-07-16T15:33:00.011-06:00

After I got the bone identified as a bird, I emailed pictures to my colleague N. Adam Smith, who at the time was a Ph.D. student at University of Texas at Austin, studying with Julia Clarke. We both agreed on the identification of the specimen as a pelagornithid, and also agreed that it could be written up quickly, and we immediately began working on the manuscript. This was the fastest paper I ever wrote - partially because each of us did about 50% of the work, and we went through a bazillion drafts (a new draft every 24-36 hours for four weeks in September and October), and we finally submitted it on Halloween.

We were pretty anal about properly figuring and labeling all the anatomic structures of this specimen in our paper; we were wholly dissatisfied with previous papers which had not labeled the relatively divergent anatomical structures of pelagornithid humeri sufficiently. Many anatomical features are fairly modified relative to non-pelagornithids, and without adequately labeled (or unlabeled) figures, it is difficult for the non-specialist to interpret their morphology; we thought we'd do everyone a favor and do it properly. One exception is Bourdon et al. (2010), who studied Eocene pelagornithids from Morocco (whose paper was also not out yet when we submitted our article).

Figure 2 from our paper, highlighting the anatomical structures of UCMP 219007.

A comparison of humeri of pelagornithids and modern pelecaniform and procellariiform birds. A- Pelagornis sp. (UCMP 219007); B- Pelagornis chilensis, late Miocene, Bahia Inglesa, Chile (holotype, from Mayr and Rubilar-Rogers 2010); C- Pelagornis miocaena, Miocene, France; D- Pelagornis sp., Pisco Formation, Peru (Pliocene); E- Morus bassanus, Gannet, extant (CAS specimen); F- Phoebastria irrorata, Waved Albatross, extant (CAS specimen); G - cf. Macrodontopteryx (synonymized with Dasornis iby Bourdon, 2010), Eocene, Belgium; H- Pelagornis mauretanicus, Pliocene, Morocco.

Many features of pelagornithids (and specifically, Pelagornis spp.) are highly divergent relative to other pelecaniformes (as you can see above, compared with Morus). Additionally, as you can see, our specimen is one of the most well preserved pelagornithid humeri now known, even more so than the beautiful holotype of Pelagornis chilensis, the humerus of which still has quite a bit of matrix encrusted and glued onto the bone, obscuring some of the fossae. One of the pneumatic fossae is actually pneumatized, and bears a pneumatic foramen that appears to connect to the internal cavity of the bone, a condition we had not read about or observed in any fossil or modern relative.

Shaded drawing I made and used for figure 3 of our paper, showing the pneumatic foramen.

Lastly, for our paper I thought I would try a skeletal reconstruction of Pelagornis. It was on my to-do list for the paper, and we already had a couple of drafts sent back and forth when Pelagornis chilensis graced the cover of JVP: it couldn't have been more timely. Although not in the original paper, associated with the press release were several skeletal reconstructions. I emailed the artist Carlos Anzures in Chile to ask for permission to modify it for our study. Well, I didn't just modify it; I redrew it by hand, reposed it, inked the drawing on vellum, and then edited the image in adobe illustrator, to eventually get something like what you see below:

Part of Figure 1 of our paper, showing the skeletal reconstruction of Pelagornis.

Next time: more on pelagornithid evolution and ecology, as well as biogeography and the implications of our find.

Bourdon, E., Amaghzaz, M., and Bouya, Baadi. 2010. Pseudotoothed birds (Aves, Odontopterygiformes) from the Early Tertiary of Morocco. American Museum Novitates 3704:1-71.

Mayr, G., and D. Rubilar-Rogers. 2010. Osteology of a new giant bonytoothed bird from the Miocene of Chile, with a revision of the taxonomy of Neogene Pelagornithidae. Journal of Vertebrate Paleontology 30:1313–1330.

A bony toothed bird from the Purisima Formation, part 1

2011-07-12T23:31:00.000-06:00

One foggy morning while doing fieldwork in the Purisima Formation, I spotted a cylindrical bone in the base of a cliff. It initially appeared hollow, but at the time of discovery, I wasn't so sure - sometimes mud and weathering products can obscure certain details of an exposed fossil. Eventually, I decided that it was most likely hollow - I scratched the inside of the bone, and had grains of ancient sand in my palm rather than bone fragments. The first step of excavating a fossil is trying to identify it: if you are positive about A) what bone you have discovered, B) what taxon it belongs to, and C) how it is oriented, you may excavate the fossil in a large block and not damage it. Sometimes you cannot limit your identification to one taxon, and this case was an example.

The end of the bone as it was exposed in the field.

Given the size of the bone, and how common marine mammals are, I assumed the most likely possibility was some sort of a fossil odontocete (toothed whale) jaw: the posterior lower jaws of odontocetes are hollow, and walled with thin bone. The only problem with this identification was that in cross section, odontocete jaws are flattened and sometimes nearly kidney-shaped - while this specimen had a more oval cross section. Nevertheless, it was my best guess at the time. When confronted by a situation like this- where you are uncertain of points A and B above, the best option is to carefully expose as much as possible until you can positively identify it. This is sometimes called "field prepping" (i.e. preparation), and sometimes may result in fragile bits of bones being broken off if you screw up or make a mistake while excavating (because field tools are less precise than lab tools, among other reasons). Aside from potentially resulting in breakage, field prepping takes time - time you may not have, if for example, you are working at low tide within the intertidal zone and have two hours left to finish.

The two sides of the unidentified bone.

Towards the end of the excavation, it was becoming clear that whatever I had found was something strange. I still thought I had an odontocete jaw, and at the time it was my best guess (I'll explain why later). I joked to myself in the field "Perhaps you've found the world's first Pliocene pterosaur!" Little did I know, I was more right about that joke than I realized at the time.

It had a slight curve to it, but it did not fan out at the posterior end like it should have if it were a jaw. I collected it in three big pieces, and upon these coming out, I saw that the sediment inside the bone was cemented - explaining why it was so well preserved, and not crushed. When I began preparing it at home, I was surprised to see that there was no enlarged mandibular foramen - again, a large hole should have been there - but instead, there was no opening in the bone.

A dentary of the bottlenose dolphin Tursiops; the enlarged posterior end and mandibular foramen can be seen on the right side of the picture (from Mead and Fordyce, 2009).

So what the hell was it? Upon leaving the field, I thought all I had was some weird odontocete with a strangely shaped jaw - perhaps a small sperm whale; they often have skinny lower jaws. However, I was once again surprised (and frustrated) by my lack of an identification, now that I had prepared the end of it (whichever end it was!). So I took a guess: some sort of a large bird bone. I did not take my thought too seriously, but the bone was in fact hollow, so I humored myself and opened up my copy of Lee Creek Volume III, and flipped to the article on the Yorktown Fm. bird assemblage.

One side of the complete end of the mystery bone.

The other end of the mystery bone.

Lo and behold, I had a match! The proximal end was a nearly exact match with the proximal fragment of a Pelagornis humerus figured by Olson and Rasmussen (2001); Pelagornis is a gigantic extinct species of bony toothed bird. I couldn't believe it: there was a very specific reason that I had not considered a bird as the owner of the unidentified bone: it was too large to represent any bird already known from the Purisima Formation, even a pelican or an albatross (in fact, it was over twice the size). I did not consider a pelagornithid simply because there are no documented occurrences of pelagornithids in younger than early Late Miocene rocks from the eastern North Pacific: there are plenty of Middle Miocene records of the bird Osteodontornis,

and a couple of records of it from the Monterey Formation. I had always assumed that they had gone extinct in the NE Pacific before the Pliocene; not only that, but this was a late Pliocene fossil. There are some Tortonian stage-like critters from the lowermost Purisima - a possible record of Imagotaria, as well as Megaptera miocaena, a Nannocetus-like cetotheriid, a possible record of Dusisiren, and some odds and ends - but this bird was far, far younger than this assemblage.Comparison of the fossil pelagornithid humerus (A, C) with the fragment from the Pliocene Yorktown Formation of North Carolina figured by Olson and Rasmussen (2001).

Check back for part 2, soon.

References:

Boessenecker, R.W. and N.A. Smith. 2011. Latest Pacific basin record of a bony-toothed bird (Aves, Pelagornithidae) from the Pliocene Purisima Formation of California, U.S.A. Journal of Vertebrate Paleontology 31(3):652-657.

Mead, J. G., and R. E. Fordyce. 2009. The therian skull: a lexicon with emphasis on the odontocetes. Smithsonian Contributions to Zoology 627:1-248.

Olson, S. L., and P. C. Rasmussen. 2001. Miocene and Pliocene birds from
the Lee Creek Mine, North Carolina. Smithsonian Contributions to
Paleobiology 90:233–365.

Sixth Triennial conference on the Secondary Adaptation of Tetrapods to Life in the Water

2011-06-21T14:00:00.014-06:00

Two weeks ago today, I delivered a presentation on the first day of the 2011 Aquatic Tetrapods conference in beautiful San Diego, California. I had eight hours on my drive down to San Diego the day before to worry about how screwed I was: the last time I gave that presentation, it was only 20 slides longer, and took 50 minutes to deliver. I practiced it once Monday morning in front of Joe El Adli (our gracious host), and Yale students Rachel Racicot and Daniel Field - I barely fit it into 20 minutes. It all worked out fine, and in the actual presentation, I finished the last conclusion slide right as it counted down to zero. This was a fresh break from SVP tradition, which dicates that cetacean research is presented on the afternoon of the last day, giving you all week to worry about the presentation. This time, I was able to relax during the entire meeting.

My title slide for my taphonomy presentation.

It would be very difficult to summarize all the research presented, but I might be able to summarize a few of the highlights that stick out in my mind. Julia Fahlke (University of Michigan) gave a fascinating talk Monday Morning about basilosaurid and protocetid cetaceans with asymmetrical crania, and implications for the evolution of hearing underwater. I'll admit, when I read the abstract I was skeptical, but her presentation was pretty compelling - I'll wait to say more until it gets published, though. Brian Beatty presented some details of his research on meningeal ossification in cetacea, which appears to not be homologous to that in many other mammals. Larry Barnes showed us a new Paleoparadoxia skeleton the LACM has been working on from the Monterey Formation; it's virtually complete, with a very large, gnarly looking skull. Olivier Lambert gave a talk coauthored by Giovanni Bianucci on a new large assemblage of bizarre ziphiid fossils dredged from the seafloor off the coast of Spain; boy, there are some real freaks. Our Australian colleague Erich Fitzgerald presented a new juvenile aetiocetid skull from the Oligocene of Washington State which he's been slowly preparing with acid; needless to say, it's a beautiful specimen. Manuel Martinez, a Peruvian who is Christian de Muizon's Ph.D. student, presented on an incredible new toothed mysticete from the Oligocene of Peru - I won't give any details, but lets just say this will be a very, very important specimen.

Frank Fish gives a mini presentation on locomotor adaptations of various marine mammals, using an assortment of articulated limbs (a walrus forelimb is seen in the foreground).

On wednesday, we went over to the San Diego Natural History Museum for an osteology workshop on aquatic tetrapods. Due to the research focus of Tom Demere (Paleo curator) and Annalisa Berta, the majority of material out on display was from modern and fossil marine mammals. There was a great assortment of wonderful stuff out, and it was amazing to be there with so many other marine mammal (and otherwise) researchers there.

Several cetacean researchers are in this photo: Toshiyuki Kimura (foreground), Mette Steeman (behind "Tosh"), and Giovanni Bianucci (background, left) and Joe El Adli (background, right).

At the workshop, I caught Brian Beatty red-handed demonstrating his very technical method to determine the relative height of the bony tentorium (here on a skull of the Amazon river dolphin, Inia geoffrensis).

For a while, Daryl Domning gave a short presentation on the locomotion and forelimb of sirenians (using a Manatee forelimb skeleton).

Here, some of the brightest minds in cetacean paleontology scrutinize one of the weirdest fossil mysticetes: a new species of Herpetocetus under study by Joe El Adli. From left to right: Mette Steeman, Joe El Adli (standing), Felix Marx (leaning over skull), Meredith Rivin (background), Giovanni Bianucci (in glasses), and Olivier Lambert (in red).

Manuel Martinez, a Peruvian researcher studying with Christian de Muizon in Paris, did not waste a chance to photobomb. Here he is photographed with a cast of the skull of the bizarre extinct edentulous* walrus Valenictus chulavistensis.

Daryl Domning again gives a short presentation, this time on sirenian crania. Here he is showing a cast of the skull of the world's largest sirenian, the extinct Pliocene species Hydrodamalis cuestae (the ancestor of the "modern" Steller's Sea Cow).

My (soon to be) coauthor Morgan Churchill photographs an articulated hindlimb of the modern walrus.

Rachel Racicot (and Daniel Field) hung out with me for a bit in the type room at the San Diego Natural History museum while I photographed some fossil pinniped material. Skulls of gigantic Hydrodamalis cuestae sit on the table behind Rachel.

Sorry for the hiatus - graduation, etc.

2011-06-17T11:14:00.004-06:00

...I've only been trying to graduate in the meantime. I'll admit, last October it wasn't looking great: I had a month and a half left of the fall semester, and one more semester after that in order to finish up all my courses, take my comprehensive exams, write my thesis, and defend it. I had already been in graduate school for slightly over two years, and now my third year was nearly halfway gone: I had a goal of submitting a draft of my thesis before the end of the semester, and at the time it didn't seem terribly realistic. I must have broken some world records though: I had my 110 page thesis written in three weeks flat (the week before thanksgiving, and then the two weeks afterward before winter break). What's strange is that it wasn't a total piece of crap either: it only required minimal editing by my advisor (and eventually my other committee members).

Apparently MSU prefers students to NOT take comps and do their defense in the same semester: I spent most of the early spring semester editing my thesis and constructing figures, and didn't get around to my comps until April 1; I did my defense only three weeks later. I am in no way trying to brag: it was hell, and if the same fate befalls you, well, you screwed up. Don't let it happen. That being said, however painful it is - it IS possible to do it all in such a short span of time if you stick to it, motivate yourself, and keep distractions (i.e. PC games, hiking, artwork) to a minimum.

My defense was on April 25 if I recall correctly: I didn't have much in the way of terribly difficult questions (I feared for the worst if certain parties arrived), and my committee really didn't have too many edits for me: many of them were time consuming because I had to look up some new articles. I spent most of finals week going over final edits, and formatting. I spent most of the two weeks after finals still working on formatting. We'll see if my thesis ever gets accepted by DGE.

Then around May 20 I drove out to California: I drove out through oregon to visit a couple fossil sites, and didn't find crap; I was home for about a day until I drove up to Lake Tahoe for the weekend, and then I had to leave there a day early to go and meet Dick Hilton up at Point Reyes, CA for fieldwork (some posts on that later). We found some great, exciting stuff...

I was home for two days after Pt. Reyes until I had to drive ALL the way down to San Diego for the Sixth Triennial conference on the Secondary Adaptation of Tetrapods to Life in the Water (SATLW). In fact, while on the beach in Bolinas in Marin County, I got a voicemail from Tom Demere (curator of the San Diego Museum and co-host of the conference) saying that my talk had been moved up to monday afternoon. I was pretty freaked out, because I had not yet shortened my talk from my 50 minute thesis presentation down to 18 minutes for the conference presentation, and I had two days to work on it.

Anyway, more about the conference soon. I think you can tell that I haven't had adequate time since my defense to do any blogging - but have no fear! The metal bars of my thesis and graduate school have (temporarily) disappeared and I can once again do 'fun stuff'.

Research featured on MSU homepage

2011-05-05T14:00:00.001-06:00

Hey Folks,

Earlier in the week, MSU news service published an article featuring my research on fossil marine mammals.

You can view the article here: http://www.montana.edu/cpa/news/nwview.php?article=9818&origin=homepage-l

Thesis defense: Passed

2011-05-03T12:02:00.003-06:00

Hey Folks,
Sorry for the unannounced month-long delay; I have had zero time to contribute to the blog because I've been busy trying to finish my master's thesis, which I successfully defended a week ago today. I've been consumed with edits and other last minute work over the last week, and still have a bit of thesis writing left for this iteration.
I'm nearing the end of the master's degree journey and all that crap; my folks are flying up here for my graduation on Friday.

Once I have my next draft in, I'll be writing up an actualistic taphonomy article on "What's currently happening to Osama Bin Laden's corpse?" In addition to its humorous objectives, it really will be an exercise in deep-sea taphonomy.

Deadline for Aquatic Tetrapods meeting has been extended

2011-04-06T14:00:00.003-06:00

For all you other marine (and aquatic) tetrapod paleontologists (and biologists and anatomists) out there, the deadline for abstract submission for the 6th Triennial Conference on Secondary Adaptation of Tetrapods to Life in Water has been extended to May 1st.

That means that any of you who were hesitant about submitting something because you didn't have time because your master's level comprehensive exams were scheduled for the same day as the abstract deadline (and you totally kicked comps in the ass like a boss, and got your abstract on marine vertebrate taphonomy submitted anyway) can go ahead and take a couple more weeks to think about what you're going to submit.

Seriously, it should be a totally awesome meeting; aside from having events at a totally awesome institution like the San Diego Natural History museum and being organized by a couple of really great paleontologists (Annalisa Berta, Tom Demere, and their postdoc Eric Ekdale), it's in San Diego.

San Diego. In June. San Diego in June.

It's like going to Mexico for spring break, except there's marine mammal fossils, other paleontologists, the San Diego Zoo, and you don't have to worry about getting beheaded by drug cartel members and someone finding your head in a cooler on the side of the road (although if you decide to take a side-trip to Tijuana that could be a possibility).

I strongly urge all marine tetrapod folks to seriously think about submitting something; there are still plenty of slots open for oral and poster presentations, and the email that Eric sent out indicates that you can submit abstracts for an oral and poster presentation.

If you have projects concerning any of the following, SUBMIT SOMETHING!

-Cetaceans & other aquatic cetartiodactyls
-Pinnipeds
-Sirenians
-Desmostylians
-Other semiaquatic basal tethytheres
-Otters
-Polar bears
-semiaquatic rodents
-aquatic sloths
-Functional morphology of any of these critters
-Plesiosaurs & 'Pliosaurs'
-Placodonts
-Other whacky sauropterygians
-Thalattosaurs
-Mosasauroids and other 'pythonomorphs'
-Ichthyosaurs
-marine crocodylians
-TURTLES
-Marine iguanas
-Hesperornithiformes
-Penguins!
-Plotopterids
-Auks and Puffins! (Alcidae)
-Flightless cormorants (and other diving birds)
-all sorts of nonmarine aquatic birds I've forgotten
-Tanystropheus!

Again, here's the conference website:

http://www.sdnhm.org/satlw/

Fossil Fur seals from Northern California, part 2: The Gilmore Fur Seal

2011-03-29T17:06:00.028-06:00

In 1948, Gretchen Burleson published a short article on some fossil pinniped jaws discovered in the Pliocene San Diego Formation, a sandstone mollusk-bearing unit that forms the hills of the San Diego area. These were some of the earliest pinniped fossils to be described from California - previously only a handful had been described, including the strange phocoid Allodesmus from the Sharktooth Hill Bonebed near Bakersfield, California, the woefully incomplete walrus (then assumed to be an otariid) Pliopedia pacifica from the Kettleman Hills, the hopelessly squashed fur seal Pithanotaria from Santa Barbara, and the even stranger Dusignathus santacruzensis from Santa Cruz.

All of these creatures were assumed then to belong to sea lions: most of them were large, and relatively robust, and differed markedly in many respects from true seals. Most of the early descriptions of pinnipeds we now know to be walruses are seemingly obsessed with comparing them to sea lions, and no doubt early workers such as Kellogg were frustrated with the alien nature of many of the fossils: they were about the same size as sea lions, but there were just so many little differences. The answer would not come until much later when decidedly modern researchers like Charles Repenning realized the true walrus affinities of many of these critters (like Pliopedia and Dusignathus).

Unlike the rather large and aberrant jaws of Allodesmus kernensis and Dusignathus santacruzensis, the fossil jaws from San Diego looked like a perfect match for a modern sea lion or fur seal: it had a shallow jaw with small triangular cuspate teeth, and the jaw was rectangular (i.e. the dorsal and ventral margins are parallel). The larger jaws of other better known pinnipeds had too many specialized features to be ancestral to sea lions: Dusignathus had widely flaring jaws without incisors and a canine that projected anteriorly, while Allodesmus lacked cusps on its postcanine teeth, which looked instead like little onions or bulbs. Burleson (1948) assigned these specimens to Pithanotaria, despite the much older age of Pithanotaria starri material described by Kellogg (1922) and the lack of actual morphological characters that identified the jaw of Pithanotaria. Burleson (1948) thought this specimen had a morphology intermediate between Pithanotaria and the modern Northern Fur Seal, Callorhinus.

Skull and dentition of a modern female Callorhinus ursinus, showing

single rooted, cuspate teeth.

In a much later paper by the preeminent paleo-pinnipedologist Charles Repenning and carnivoran researcher Richard Tedford (1977), this specimen was briefly discussed and they concluded that it did not represent Pithanotaria and was likely much closer to Callorhinus ursinus. After observing trends within the dental evolution of walruses like Imagotaria, Repenning and Tedford (1977) had identified the utility of the stage of root fusion as a taxonomic guide. For example, all modern otariids (fur seals and sea lions), the walrus, and some seals have single rooted teeth, while primitive pinnipeds and terrestrial carnivorans retain a number of double and triple-rooted teeth. For whatever reason, these root lobes coalesced through time and resulted in single rooted teeth in a number of taxa.

The dentary of the holotype of Callorhinus gilmorei, from Berta and Demere 1986.

Repenning and Tedford (1977) were surprised that Burleson (1948) had not noticed the interesting configuration of the tooth roots of this specimen: the third and fourth premolars and the molar were still double rooted, while only the first and second premolars were single rooted; in the modern Northern Fur Seal, Callorhinus ursinus, all the lower premolars and molar are single rooted. It was indeed a fur seal, but retained some interesting primitive features.

In 1986, after an extensive excavation of a bonebed in the San Diego Formation that would be christened the Mission Hills Bonebed, additional remains of this fossil pinniped were discovered including several jaws, teeth, skull fragments, and postcranial bones. The discovery of a partial skeleton of an immature female skeleton allowed Annalisa Berta (San Diego State University) and Tom Demere (San Diego Natural History Museum) to describe the San Diego fur seal as a new species - and sure enough, they found that its features placed it as a close relative of the modern Northern Fur Seal, Callorhinus. They named it Callorhinus gilmorei, named after Dr. Raymond Gilmore. In other regards, Callorhinus gilmorei was a relatively small fur seal - substantially smaller than modern skeletal remains, with less strongly developed cusps on postcanine teeth, and a more 'primitive' state of root fusion.

The new specimen of Callorhinus gilmorei from the Rio Dell Formation of Northern California described by Boessenecker (2011)

Subsequently, Kohno and Yanagisawa (1997) reported a tiny partial jaw from the late Pliocene of Japan. This jaw exhibited double rooted cheek teeth (although the anterior premolars were not preserved), and had accessory cusps on the cheek teeth, so they identified it as Callorhinus gilmorei. This extended the range of the Gilmore fur seal to the western Pacific - similar to the range of the modern Callorhinus ursinus.

Needless to say, I had a few ideas to follow once I started looking into Bushell's fur seal specimen. Fossils of C. gilmorei had so far only been found in Middle to Late Pliocene deposits, whereas in the late Miocene and earliest Pliocene of Japan, California, and Mexico the earlier fur seal Thalassoleon occurred (which has all double rooted teeth, and lacks cuspate cheek teeth, among other differences). The new specimen only has one cheek tooth - but it has a well developed accessory cusp, like C. gilmorei, and the first two premolars are both single rooted - also like C. gilmorei. In addition, it is relatively small - many other modern otariids are substantially larger. Furthermore, C. gilmorei appears to be the only middle-late Pliocene otariid in the entire Northeastern Pacific fossil record, which made the identification process somewhat easier.

Next up: Other fossil otariids from California and Oregon, and the Pleistocene Callorhinus
specimen.

References:

Berta, A., and T. A. Demere. 1986. Callorhinus gilmorei n. sp., (Carnivora: Otariidae) from the San Diego Formation (Blancan) and its implications for otariid phylogeny. Transactions of the San Diego Society of Natural History 21:111–126.

Boessenecker, R.W. 2011. New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution. Journal of Vertebrate Paleontology 31:2:454-467.

Burleson, G. L. 1948. A Pliocene pinniped from the San Diego Formation of southern California. University of California Publications in Zoology 47:247-254.

Kellogg, R. 1922. Pinnipeds from Miocene and Pleistocene deposits of California. University of California Publications, Bulletin of the Department of Geological Sciences 13:23–123.

Kohno, N., and Y. Yanagisawa. 1997. The first record of the Pliocene Gilmore fur seal in the Western North Pacific Ocean. Bulletin of the National Science Museum, Tokyo 23:119–130.

Repenning, C. A., and R. H. Tedford. 1977. Otarioid seals of the Neogene. US Geological Survey Professional Paper 992:1–87.

Only four more days to submit an abstract for the Aquatic Tetrapods Conference!

2011-03-28T20:01:00.004-06:00

All you marine vertebrate folks out there reading my blog (admittedly a very small minority of a minority of the vert paleo community) and not working on the abstract you should be for the Aquatic Tetrapods meeting, listen up! Abstract submission closes on friday, April 1st: I've been informed that not too many people have registered so far, so get on it!

FYI: you have to register for the meeting before you can submit an abstract.

For more information, check out the conference website:

https://www.sdnhm.org/satlw/index.php

Fossil Fur seals from Northern California, part 1: discovery

2011-03-26T20:39:00.008-06:00

Earlier this week saw the publication of my third article, concerning fossil fur seals of the genus Callorhinus from the Pliocene and Pleistocene of Humboldt County in Northern California. This paper has been in the works since 2006; I presented a poster on this topic at SVP in 2007. I did some of the initial research in 2006 and 2007, and after my SVP poster, I tried a couple more drafts of the manuscript - but it, along with a couple of other projects, fell by the wayside until I started graduate school. It wasn't until I had the herpetocetine jaw paper off my plate that I returned to this project, and in may of last year I submitted my completed MS to the Journal of Vertebrate Paleontology after three years of intermittent research.

The first page of Boessenecker (2011)

The story really starts in 2004. My buddy Ron Bushell, who helped me identify many of my fossils when I was still in High School, was collecting at a fossil site in Humboldt County, California. At this particular locality, he was looking for large concretions from the Rio Dell Formation which occasionally bear beautiful scallops (Patinopecten) the size of dinner plates, and incredible 6-10" long gastropods.

Ron and his collecting partners walked down the riverbank looking for nodules bearing mollusks, and thought he had hit the jackpot when he found a large nodule, about 2 feet in diameter, just sitting there in the gravel bar. Now, Ron is an experienced nodule collector - he's spent a lot of time collecting nodules with mollusks from the Pliocene and Pleistocene of Humboldt County, and Eocene crabs from Oregon and Washington.

So, if you're a nodule collector, naturally you take out a sledge hammer and attempt to destroy the concretion. Many concretions have nothing in them, and it is better to crack them in the field rather than lug them home and find out later (at some crab localities, Ron knows well enough which concretions will have crabs, and which ones won't, and packs them all out, and cracks them in his garage). Well, he broke this concretion open, and instead of white shells being exposed, familiar (but much rarer) brown fragments flew out onto the river bank - he immediately knew that he had found bone.

Initial preparation of the Bushell specimen.

Normally, Ron would keep any vertebrate fossils from this locality, due to their rarity. However, he also noticed a tooth fragment - and he knew he had found something pretty important. So, just like any crab or mollusk fossil, he collected all the pieces, took them home, and glued them all together in his garage, and begun airscribing the fossil.

Continued preparation of the Bushell specimen.

As it turned out, Ron had found two associated lower jaws (left and right) of a small fur seal, preserved beautifully in relief in a large concretion. He posted these photos on the old "Collecting fossils in California" forum, and I was very interested once I saw it. After a few emails, he offered to let me study the specimen - an opportunity I was most excited for.

Finished preparation of the Bushell specimen.

The Bushell specimen as it was when I first saw it.

The following summer, my fiancee (then girlfriend) and I drove out to California for the summer, but took a detour through Oregon and Humboldt County in order to visit Ron and pick up this beautiful specimen. Thanks to Ron's generosity, this fossil was made available to study - and now (finally, five years later) Ron's wish that it be studied finally culminated in my paper in the Journal of Vertebrate Paleontology.

Next up - introduction to the "Gilmore Fur Seal", Callorhinus gilmorei.

Boessenecker, R.W. 2011. New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution. Journal of Vertebrate Paleontology 31:2:454-467

NYCOM "Evolution of Whales and Dolphins" website is finally up!

2011-03-21T11:55:00.004-06:00

A new website detailing the evolution of cetaceans is up on the New York College of Osteopathic Medicine website, and can be explored here.

Jonathan Geisler asked me to write for this website last year, and in February I flew to Long Island to visit NYCOM and sign all the necessary paperwork for the website. It is still very much a work in progress, but we hope to eventually have a large body of public-friendly articles on the website detailing many aspects of whale evolution and the cetacean fossil record.

Specific pages include:

Summaries of recently published articles on whale evolution

Summaries of fossil and modern cetaceans (modern cetaceans will come soon)

Research papers by undergraduate students (Georgia Southern University)

Georgiacetus!

Project Personnel

Enjoy, and stay tuned for updates!

Research featured in the Santa Cruz Sentinel

2011-03-16T12:06:00.002-06:00

Hey Folks,

My research with Frank Perry concerning bite marks on fur seal bones was recently highlighted in a recent article in the Santa Cruz Sentinel. Check it out!

http://www.santacruzsentinel.com/ci_17604819

New published article (Part 2): taxonomic problems with Herpetocetus and "cetotheres"

2011-03-05T17:06:00.006-07:00

The "cetotheres" have long been a troubled group of fossil baleen whales. Typically, they have throughout there long and confusing taxonomic history been treated as a wastebasket group to include all extinct mysticetes that lack the synapomorphic (i.e. distinguishing) features of the extant groups of baleen whales (gray whales, Eschrichtiidae; rorquals, Balaenopteridae; and right whales, Balaenidae). For a very long time, this group included strange early-diverging mysticetes such as Parietobalaena, Pelocetus, Diorocetus, Aglaocetus (all Miocene mysticetes from the Chesapeake Group of Maryland and Virginia), Cophocetus from Oregon, Cetotherium from the Miocene of the Ukraine, and my favorite mysticete, the problematic Herpetocetus (among others). Many authors during the latter half of the twentieth century doubted that this was a natural grouping, and I suspect that the proliferation of this notion in the literature has more to do with taxonomic laziness on the behalf of mysticete systematists than anything else.

While the taxonomic problems associated with "cetotheres" are a topic for a different post altogether, a brief summary is warranted for the backdrop of the implications in my recently published article. With the advent of cladistics, some studies found that 'cetotheres' are a paraphyletic group of stem-mysticetes (i.e. that they are an unnatural group characterized by primitive rather than derived features). For several years it seemed that the term 'cetothere' should be shit-canned for all eternity, until Bouetel and de Muizon (2006) published a large study on a small Herpetocetus-like 'cetothere' from the Pliocene and latest Miocene of Peru, called Piscobalaena (after the Pisco Formation). They found that some 'cetotheres' form a natural monophyletic group (i.e. a group that is defined on derived features that includes all the descendants of a common ancestor). Because this clade included Cetotherium rathkei, they called this clade the Cetotheriidae sensu stricto, and other 'cetotheres' the cetotheres sensu lato. This same relationship has been supported by several other phylogenetic analyses.

The lectotype jaw of Herpetocetus scaldiensis. From Bouetel and de Muizon, 2006.

Within the true cetotheres, Herpetocetus is the most derived member, and also the youngest surviving member. As previously mentioned, it was based on a lower jaw from the Pliocene of Belgium. When it was described in 1872, a type specimen was never selected, and the lower jaw was selected as a 'lectotype' over thirty years later. The jaw of this animal is pretty distinctive,
Subsequently, many authors have used the distinctive jaw morphology to refer isolated jaws to the genus Herpetocetus. A nearly complete mysticete skeleton from Japan, including a skull, was identified as Herpetocetus due to its jaw morphology. Subsequently, fossils of Herpetocetus have also been reported from the Pliocene and latest Miocene (6-2 Ma) of California, and the early Pliocene (3-5 Ma) of the east coast (North Carolina), basically indicating a 6-2 million year record only in the Northern Hemisphere.

So you can see, when I first thought long and hard about these early Late Miocene (10-12 Ma) Herpetocetus lookalikes, why I was somewhat confused. Herpetocetus also has distinctive earbones and skulls (based on specimens associated with jaws), and there aren't any earbones or skulls with the typical "Herpetocetus morphology" that occur any older than 6 Ma (there is one undescribed skull from the 6.8 Ma Santa Cruz Mudstone I've identified as Herpetocetus aff. bramblei). What is known from the 10-12 Ma Santa Margarita Sandstone, in addition to the jaws in question, is Nannocetus eremus.

The holotype braincase of Nannocetus and a quick and dirty reconstruction based on the rostrum of Herpetocetus sendaicus.

Nannocetus is a really tiny (greatest width across the skull is about 10 inches) weird mysticete, originally described in 1929 by Remington Kellogg. A second specimen from the Santa Margarita Sandstone was described by Whitmore and Barnes (2008), and is the only other known 'true cetothere' from the Santa Margarita. However, Nannocetus is not yet known by a jaw; could Nannocetus be the rightful owner of the two dentaries I described?

If so, then the supposedly distinctive anatomy of the lower jaw of Herpetocetus is not distinctive, and raises important questions about referring isolated dentaries based on their morphology. Additionally, this problem raises an even more important issue: what, then, of fossil baleen whales described solely based on isolated lower jaws? Most of them are probably invalid, because lower jaws *might* only be diagnostic at the supraspecific level (i.e. at the level of a genus or subfamily - whatever the hell those are). "But Bobby, the type species of Herpetocetus is based only on a lower jaw!" Aw, crap. That's right. We've now come full circle: Herpetocetus may or may not be a valid name in the first place, if jaw morphology is insufficient for taxonomic purposes.

Before us mysticete taxonomists go off ready to sink Herpetocetus as a nomen dubium, there are a few important things I pointed out in the article which should be remembered: 1) The fossil dentaries DO show a couple of features distinct from Herpetocetus, including a mandibular foramen with a a lanceolate opening, unlike Herpetocetus. 2) Although highly likely, it is possible that these dentaries are not Nannocetus. However the age discrepancy does mean something in and of itself. 3) Distinctive skull fragments showing some synapomorphies of Herpetocetus were also in the "type series" described in 1872, so it is unfair to say that it was based only on a lower jaw.

With those exceptions in mind, I hope my new article has established some caveats for mysticete workers. Additionally, this work has identified the possibility that mysticete jaws are perhaps diagnostic to the generic level; this still means they are unsuitable as holotypes, but that they are by no means useless - the jaws of mysticetes tell us quite a bit about the animal's feeding and its relationships (although they are not as fine-tuned as, say, parts of the skull). Hopefully future fossil mysticete holotypes will be designated only on material that is really diagnostic, and hopefully will include comparable elements like earbones, braincases, and (also hopefully) the posterior end of the lower jaw.

New artwork IV: Tyrannosaurus rex maxilla

2011-03-04T04:00:00.000-07:00

For quite a while I've wanted to draw a theropod maxilla. They're pretty neat looking elements, and tyrannosaurid maxillae at that are pretty rugose, and have some interesting textures. I did this drawing once I got back from New York earlier in the month. I'm very happy with this piece, and it isn't very big - maybe 8" wide.
Here's a quiz: what's important about this specimen? The specimen # is UCMP 118742.

New artwork III: Smilodon life restoration

2011-03-03T12:47:00.001-07:00

Late last year I was asked by my buddy/coauthor Morgan Churchill to draw a life restoration of Smilodon or some other machairodontid for a new exhibit at the University of Wyoming Geology Museum.
Unfortunately, I didn't really get a chance to start it until January, and I finished it a few weeks ago. This was largely an experiment for me, as I've never really drawn fur before; I've had plenty of experience drawing hair in portraits of people, but never really furry mammals. I've never really drawn any life restorations of (non-human) mammals before, for that matter. I suspect that doing something hairless like marine mammals might be quite a bit easier. Anyway, I clearly need more practice. Perhaps next time, I'll try and copy a photograph, to at least get some experience with texturing fur, instead of attempting to "paste" it onto a fossil face I've never seen before.

Any way, I'm relatively happy with the outcome. I initially wanted to draw it with it's mouth closed, but I figured that would look less impressive for the museum exhibit. So, yawning is a behavior that inadvertently shows off an animal's oral weaponry that is far more common than snarling, baring of teeth, etc. - and very few paleoartists have attempted Smilodon yawning. Almost all Smilodon art I've seen depicts the animal snarling, which of course looks very impressive, but it does get a little boring.

Boessenecker & Perry 2011 is the featured Palaios article for March 2011

2011-03-02T20:23:00.003-07:00

Last night, after a delicious dinner at one the best steakhouses in Montana, I returned to my apartment to find an email from the editors of Palaios. They both nominated my recent article "MAMMALIAN BITE MARKS ON JUVENILE FUR SEAL BONES FROM THE LATE NEOGENE PURISIMA FORMATION OF CENTRAL CALIFORNIA" to be the featured Palaios article for March of this year.

What does that mean exactly? First and foremost, that means my article is now open access, and freely available (to everyone) here (click here for the pdf). So, download the article while you still can access it! You have 30 days. Secondly, it means that I totally kick ass.

You can see the list of featured articles (including mine) here. Not only is my article right up at the top, but it's also one of the only ones in all caps. Too bad they couldn't put in bold, italics, and make it flash different colors while they were at it.

NOTE: Many of these links may not work past the end of March.

New published article (Part 1): herpetocetine jaws, and an example of finding a "simple" research project

2011-02-27T22:00:00.001-07:00

The new issue of PaleoBios, the paleontology journal published by UCMP at UC Berkeley, includes my new article on herpetocetine jaws from the Santa Margarita Sandstone in central California. During the fall of 2008, I was in my first semester of graduate school, and was taking a difficult, time-intensive course on advanced stratigraphy. At the time, I already had two articles I had been working on: one on my undergraduate research concerning a new fossil vertebrate assemblage from the Purisima Formation, and another on Plio-Pleistocene fur seals from the Wildcat Group in northern California (both are currently in press). However, neither was in any shape to be published anytime soon - one was only half written, and the one that was nearly finished needed a lot of work (i.e. quality control). I needed a new manuscript to work on, to give me something to do that semester aside from stratigraphy, which had started to eat away at my brain. In other words, I needed to start something fresh from scratch, with a clear beginning, a clear end, and a clear message.

The right dentary of UCMP 85431. Scale bar =10cm. From Boessenecker (2011).

A month earlier, I had given a presentation (coauthored with Jonathan Geisler) on a new skull of Herpetocetus bramblei I had collected from the Purisima Formation in 2007. While ruminating on possible projects, I suddenly remembered a partial lower jaw from the Santa Margarita Sandstone that looks a lot like the lower jaw of Herpetocetus*. The problem is, the Santa Margarita Sandstone is early Late Miocene in age (10-12 Ma), while the oldest known bona fide specimens of Herpetocetus are latest Miocene to earliest Pliocene in age (~5 Ma). In fact, the oldest known described specimen is the fragmentary type specimen of H. bramblei, which is right about 5.33 Ma. So, this specimen (UCMP 85429) is MUCH older than any known specimen of a "true" Herpetocetus.

*All species of Herpetocetus have relatively similar lower jaws, and currently the lower jaw has only been described for the type species, Herpetocetus scaldiensis (the type specimen of which is a lower jaw - more on this later).

The left dentary of UCMP 85429; scale bar = 10cm. From Boessenecker (2011).

The lower jaw of baleen whales has long been assumed to be a fairly diagnostic element, at least in certain groups. Herpetocetus scaldiensis certainly has a very distinctive mandible. Other fossil mysticetes certainly have distinctive mandibles as well. Many fossil mysticetes (H. scaldiensis, Balaenoptera davidsonii, Archaeschrictius ruggieroi, etc.) have been described just off of their lower jaws. Are dentaries really that diagnostic? Perhaps. Demere (1986) used mandibular features to reevaluate "Eschrichtius davidsonii" from the San Diego Formation, which was a chunk of a 30% complete mandible, missing the anterior and posterior ends. Being able to refer a new dentary to this taxon, he demonstrated that the "davidsonii" morphotype was actually a rorqual, and assignable to the genus Balaenoptera, which led to its recombination as Balaenoptera davidsonii. Clearly, mandibular morphology is important, and can be used to assess the taxonomy of certain groups, and 'fix' the taxonomy of certain problem taxa. Are these specimens the oldest known records of Herpetocetus?

Reconstructed lower jaw of Herpetocetinae genus and species indet., based on UCMP 85429 and 85431. From Boessenecker (2011).

Reflecting upon the known fossil record of "true cetotheres" - relatives of Cetotherium and Herpetocetus (an entire other topic worthy of its own post) - I was able to formulate some interesting questions I could ask (and attempt to answer), which would make a nice core of an article. With these objectives in mind, I started taking copious notes on the anatomy of the fossil specimens, and eventually typed these notes up into an anatomical description for the article. By the end of the semester, I had a manuscript that was about three-quarters finished. During spring 2009, I wrapped up the discussion, and constructed some figures. I had a few people look at it and make some comments. Morgan Churchill looked at it late in spring, and had some of the most constructive and useful edits. That summer, I TA'd the Geology Field Course for MSU, and during some of the weeks, I took my manuscript out into the field with me, along with a red pen. In between helping students, I sat out in the hot sun, and critically examined every sentence in the manuscript. I even drafted one of the figures (on vellum, with nice pens) around the campfire one night after a few beers. By the end of the second to last project at field camp, I had all my edits finished, and I sent it off to PaleoBios for review.

To be continued...

Boessenecker, R.W. 2011. Herpetocetine (Cetacea:Mysticeti) dentaries from the Upper Miocene Santa Margarita Sandstone of Central California. PaleoBios 30:1:1-12.

Deméré, T.A. 1986. The fossil whale, Balaenoptera davidsonii (Cope 1872), with a review of other Neogene species of Balaenoptera (Cetacea: Mysticeti). Marine Mammal Science 2:277–298.

New artwork II: 'rediscovered' specimen drawing

2011-02-26T17:31:00.006-07:00

About two months ago, I was cleaning off my desk and found a sheet of vellum paper with an old specimen drawing I had done. This drawing was is of a pair of associated dentaries of the Pliocene fur seal Callorhinus gilmorei. I first presented on this fantastic specimen on my 2007 SVP poster at the Austin, TX meeting.

Unfortunately, I discovered this about three months after my manuscript describing this fossil was accepted in JVP, and there was no way to include it in the published article. To be honest, I could probably do better now, but I think it turned out reasonably well for a journal article figure. In the future I'm going to do a lot more technical illustrations of individual specimens, partly as practice, but also to showcase myself.

Stay tuned! The article will be published in the March 2011 issue of JVP: that's sometime in the next couple of weeks. (Holy god, it's March in only 48 hours!). More artwork is on its way.

Boessenecker, R.W. In Press. New records of the fur seal Callorhinus (Carnivora: Otariidae) from the Plio-Pleistocene Rio Dell Formation of Northern California and comments on otariid dental evolution. Journal of Vertebrate Paleontology 31:2. 14pp.

New artwork I: Cynthiacetus reconstruction

2011-02-24T14:16:00.001-07:00

Hey folks,

Some of you cetophiles may have already seen photos of this specimen floating around on the internet. I thought the mount was pretty dynamic, and would work well as a skeletal reconstruction - so I did it. A photo of this specimen which has thus far only been identified as cf. Cynthiacetus is featured in a recent paper by Christian de Muizon.

Cynthiacetus is a dorudontine archaeocete that was originally described from the Eocene of Mississippi by Mark Uhen. He also referred a few vertebrae and a partial skeleton to this taxon from the Eocene of Egypt. This new skeleton (and I am not sure how complete it is) is from the Eocene of Peru, and is part of a large new collection of Peruvian archaeocete cetaceans we will be hearing about over the next few years.

Return to the thanksgiving odontocete locality

2011-02-24T01:51:00.006-07:00

Over winter break Chris Pirrone and I returned to the locality where, a month prior, we had excavated a complete odontocete skull. If you recall, when we collected the specimen we had to excavate and pedestal the skull sideways, rather than the normal way (downwards) that most paleontologists are used to. When I had seen the skull at the end of the summer, it was only a few feet above the sand. I knew that over thanksgiving, there would be a very good chance that the sand would all be gone due to the rough weather which tends to erode away the beaches.

Luckily, at thanksgiving there was a three foot-wide 'rim' of the summer beach left, and closer to the ocean, the beach sand was about 8 feet lower. Fortunately, we had just enough time to collect the fossil. When we returned in January, this sliver had been completely eroded away, leaving the excavation pit about 9 feet above the beach and well out of reach. In the above photo, you can see it about left center.

And here I am pointing to it. It would still have been accessible by ladder, but that would have been a real pain, and I'm pretty sure after standing on a ladder for five hours, it's almost a guarantee that you'd fall off.

Comparison between Thanksgiving 2010 and January 2011. The two photos are taken from nearly the same position (note the rock in the foreground) but the more recent photo is taken from further away from the cliff.

Otherwise, after initial preparation, the fossil appears to be a juvenile Parapontoporia, with a partial dentary, and both tympanoperiotics. The tympanoperiotics are now fully prepared, and were articulated, and sitting above the bony nares and the vertex of the skull (i.e. in contact with the dorsal surface). As the skull was upside down, the earbones must have fallen out, and then the skull rolled over on top of them. I'll have pictures soon.

Trip to New York

2011-02-19T13:33:00.005-07:00

New York City and Central Park from the 4th Floor of the
American Museum of Natural History.

A few weeks ago I took a trip to New York in order to be officially hired as a writer for a website on whale evolution that Jonathan Geisler (New York College of Osteopathic Medicine) is collaborating on with John Gatesy (UC Riverside) for an NSF grant. This trip was convenient because Jonathan and I are collaborating on a couple of research projects together, including the description of a fragmentary pilot-whale like skull from the Purisima Formation, as well as working on a large body of Herpetocetus material from Northern California. Once the website is up, I'll go into quite a bit more detail about it.

In 2008 I presented a talk (my first oral presentation) at SVP on a new skull of Herpetocetus bramblei I had found the previous year. The skull is pretty nice, and has about half the rostrum and a complete braincase, with earbones (tympanic, petrosal, stapes, incus, malleus). Because of its completeness and preservation, it will be a daunting task just to describe it. Fortunately (or unfortunately, depending upon how you look at it!) I have since collected another skull with a complete rostrum, and another (slightly less complete) skull from higher up in the Purisima Formation which may represent a younger species. So, including a fragmentary braincase at UCMP, there are four Herpetocetus crania, about a dozen petrosals, several tympanics, a half dozen dentaries, and some postcrania that we need to describe. Anyway, we didn't really work on this project at all.

One day during the trip we went in to the AMNH to look at some modern odontocete crania for comparison with the fossil pilot whale. A year and a half before, when I presented my poster on it at SVP (the 2009 Bristol meeting), I had identified it as Globicephala sp. at the time; fossil delphinid expert Giovanni Bianucci mentioned to me that he was not quite convinced that it belonged in that taxon. At the time I just identified it as best I could, without really having access to crania of other globicephalines like Pseudorca, Peponocephala, and Feresa. During our AMNH trip, we came to a similar conclusion as Giovanni - it's got too many differences to be in Globicephala, as it shares some other similarities with Pseudorca and Feresa.

Jonathan Geisler puzzles over fossil and modern globicephaline skulls.

However, it still definitely falls within the clade Globicephalinae, and that's what's important any way. I'll go into more detail about the ramifications of this fossil later on once we've at least submitted our paper - hopefully sometime early summer I'll have this one (manuscript #6) off.

Here I am (with appropriate shirt for the visit) with a beluga (Delphinapterus) skull.

Perhaps in a later post I'll post some of the pictures I took on a 15 minute dash through the fourth floor exhibits (which was all the time I had before we wanted to leave).

Nobody likes Aetiocetus =(

2011-02-14T14:09:00.000-07:00

I randomly came across this while trying to look up information for a summary about Aetiocetus weltoni I'm writing for a webpage (more info on the new webpage soon!).

Anyway, I became the first person to officially 'like' Aetiocetus. Please think of the toothed mysticetes; the Aetiocetus weltoni holotype specimen is alone this Valentine's Day. Please show Aetiocetus some love.

Broken tailbone

2011-02-14T01:43:00.006-07:00

I failed to mention this a year ago when it happened, but during spring break last march (2010) I broke my tailbone way up in a quarry in the Santa Cruz mountains. I was sliding down a steep gulley carved in the Santa Margarita Sandstone, attempting to access a bonebed. I can't even remember if I got anything or not, but at one point, I realized I could not go back up as I had done before.

The dreaded gulley I dropped out of, right onto my #@!.

I looked below me - I had another ten feet of gulley or so before it dropped off. It looked like a large talus cone of sand about fifteen feet below me, which is also exactly what you'd expect, you know, at the bottom of a gulley like that. It looked like a six foot drop or so, nothing bad - I've jumped off cliffs down to the beach from a little bit higher with no consequence, so I thought I might as well. So I slid down to the end, and dropped down, with both toes pointed downhill. Only, the drop ended up feeling a little longer than 6 feet. When I landed, my feet bounced off the "talus cone", which was in fact a thin (1 inch?) veneer of sand over a smooth sandstone surface, my legs flew up in the air, and I fell back onto my tailbone. Now, this wasn't like my feet slowed me at all - all this took place within a second, and I effectively fell the entire distance with my tailbone intercepting 90% of the impact.

The red line shows the distance I fell onto my tailbone.

Naturally, I sat there writhing in pain for a good fifteen minutes, after I crawled out of the hot sun. Luckily no one was in the vicinity (it was pretty embarrassing), or perhaps if they were, they were driven away by a ten minute string of expletives. I've never broken a bone before (except a possibly less serious tailbone break during a snowmobile mishap in 2006), and I gotta admit, the pain was pretty intense. It's strange, it was really dull, but so intense it made me nautious for the better part of two hours. It took a while before I felt like I wouldn't puke from it. And damnit, I had just eaten a nice homemade lunch - I didn't want it to go to waste! Fortunately, after a while I kept on prospecting, and found a beautiful partial Imagotaria downsi (early walrus) dentary.

Chris Pirrone surveys the dreaded quarry.

In December I returned to the locality with my buddy Chris Pirrone, and we found a LOT of bone. It appeared as though an entire mysticete dentary (the single largest bone to ever evolve) that had formerly been about 5 or 6 feet long had eroded out of the cliff into about thirty pieces and was beyond salvage. However, we did find what appears to be an Imagotaria metapodial, which will be nice when I get it prepared. Anyway, I took these photos of the gulley, and when we returned to the site, it looks like I fell 8-10 feet instead of 6. Fun!

Anyway, the day I broke my tailbone, I continued my day and hit up about four more localities - sure, driving was awkward as hell, but standing didn't hurt one bit. In fact, it seemed to help. I actually ended up finding some great stuff that day. I thought about returning home, but I realized all I'd be doing there would be sitting around, which would hurt more than a day of fieldwork along the pretty coastline. What really sucked was the drive back to Montana - I had to pull over every hour and a half or so to get up and walk around.

The moral of the story is: be careful, and don't get cocky (or, overexcited and lose track of your surroundings). And if you must do what I did, land sideways with one foot downhill, like you're surfing. Never go face down, or facing the cliff (I can imagine a faceplant into the rock wouldn't be too nice). Or tuck and roll.

It's now 11 months later, and my tailbone still hurts if I sit in a bad chair for a couple hours.

Mammal bite marks on fur seal bones, Part 3

2011-02-10T19:12:00.004-07:00

Within 48 hours of my paper being published, I tried seeing if I could find anything if I searched for 'pinniped bite marks' on google. Sure enough, I saw that Dr. Alton 'Butch' Dooley had already covered it (thanks, Butch!), but I saw something else that made me angry and very excited at the same time. This was an article on feeding damage induced by a leopard seal attack on a human.

Pair of tooth punctures from the leopard seal attack.

Yes, the loss of human life is very tragic and all, but this is really exciting! As aggressive as leopard seals are (and as bad a rap as they get in movies like March of the Penguins and Happy Feet), and as scary as some other pinnipeds are, they normally don't attack humans, and if anything are typically wary of humans. This attack involved the 28-year old Kirsty Brown, a scientist in Antarctica, who was snorkeling at the time. The seal attacked her, and dragged her under water for 6 minutes to a depth of 70 meters (!). That's pretty incredible. Observers estimated the seal was 4-4.5 meters long.

What is most interesting about this paper is that the punctures figured above in the article are very similar to those that Frank Perry and I described (Boessenecker and Perry, 2011). The bite mark on the radius is most similar, as the puncture penetrated the cortex, and left a peripheral ring of depressed bone, just like these. It is difficult to say because the article did not go into the details much, but although these punctures are undoubtedly canine punctures, they appear much too close together to be from the same bite. Perhaps these were from the same canine on different bites, or something along those lines.

Unfortunately, this paper was published in 2007, and had I known about it, I would have totally cited it. In fact, this paper makes the pinniped origin of the bite marks seem all that more probable. And, on top of that, it also bolsters the case that these bone modifications have been identified correctly. So, my apologies to Guy Rutty; I didn't mean to not cite you, and I certainly wish I had.

Rutty, G.N. 2007. Pathological findings of a fatal leopard seal attack. Forensic Science, Medicine, and Pathology 3:57-60.

Mammal bite marks on fur seal bones, part 2

2011-02-02T20:35:00.007-07:00

A few months after I collected the radius, I was invited to go examine Frank Perry's private collection. He's donated the majority of his material to UCMP, LACM, and the Santa Cruz Museum, but there was some remaining material. Several specimens he allowed me to borrow and prepare, including a partial juvenile Parapontoporia cranium, a walrus vertebra, and several fur seal bones. One of these was a very small humerus from a fur seal pup, roughly the same size individual as the radius I mentioned earlier. This specimen also happened to have a circular depression with a ring fracture, although it is much more shallow, and larger. This may be attributable to a larger, blunter tooth. Both of these specimens are probably attributable to the species Thalassoleon macnallyae, although in the article the bones are only identified to the family otariidae.

The right radius of a juvenile fur seal in anterior (left) and lateral (middle) views, and a closeup of the bite mark (right).

So, what caused these? Many, many, many studies have been published on shark tooth inflicted bite marks, which are typically linear gouges. These gouges are sometimes associated with removed 'chunks' of bone, but never have any fractures. These are obviously not linear gouges, and instead appear to be the result of the bone surface being pushed in. Circular holes can be caused by boring clams (pholad clams), but these are eroded, and do not result in fracturing. As it turns out, many similar tooth marks have been reported for conical mammalian teeth, of terrestrial mammalian predators and scavengers. One single similar tooth mark has been reported for a marine mammal: a skull of a juvenile sea lion (Eumetopias) from the Pleistocene of British Columbia (see the paper for more comments on this article). In fact, this is only the second reported occurrence of probable mammalian bite marks on fossil marine mammal bones.

Figure 2 from Boessenecker and Perry (2011) showing the bones and bone modifications.

The next question is, what type of mammal has the dental equipment capable of inflicting this sort of damage? Several pinnipeds, including the bizarre walrus Dusignathus santacruzensis, have teeth small enough to inflict these punctures. Most dolphins have teeth that are too small, and too closely spaced to make these punctures. Larger odontocetes, including the beluga relative Denebola, have larger teeth which are spaced far enough apart to form the punctures. Recently, Jonathan Geisler, Frank Perry, and I presented a poster on a pilot whale-like delphinid, and something the size of this cetacean could easily have produced the bite marks. The possibility remains that a terrestrial carnivore, like a canid, felid, or ursid; modern mammalian carnivores often prey upon or scavenge upon pinnipeds on shorelines. Lastly, the fur seal Thalassoleon has teeth that could produce the punctures. But Thalassoleon is the same species, you say! Well, oddly enough, extant fur seals and sea lions frequently commit infanticide - killing juveniles of their own species, sometimes in order to feed, other times as a part of aberrant sexual behavior where juveniles are mistaken for females.

Table of biogenic bone modifications from Boessenecker and Perry (2011) reported from marine vertebrate bones.

Unfortunately, it isn't possible to narrow the possibilities down any further. I'm getting tired, so stay tuned for part 3.

Mammal bite marks on fur seal bones, part 1

2011-02-02T02:59:00.007-07:00

It's approximately four in the AM in beautiful Long Island, New York, and this most recent blog post is brought to you by insomnia! I tend to not fare well in unfamiliar hotel rooms unless I'm relatively exhausted. Even though I'm running on a total of four hours of sleep since the night before I flew out to New York, I fared pretty well today. Tomorrow, I have a visit to the American Museum of Natural History in NYC, and Jonathan Geisler and I will be examining globicephaline dolphin skulls; the Globicephalinae are a clade of delphinids (oceanic dolphins) including pilot whales (Globicephala), Risso's Dolphin (Grampus), and false killer whales (Pseudorca). We're working on a short article together on a very fragmentary large odontocete skull from the Purisima Formation in Santa Cruz that shares some features in common with Globicephala.

But I'll talk more about that project later. More importantly, over this last weekend my first article was published - "Mammalian bite marks on juvenile fur seal bones from the late Neogene Purisima Formation of central California", which I coauthored with my friend and colleague Frank Perry of the Santa Cruz Museum of Natural History. And, oddly enough, right as I am typing this up now, I see that my friend Dr. Alton "Butch" Dooley at the VMNH has already beat me to the punchline (thanks for the free publicity, Butch!), and has discussed my new paper on his blog, and compared it with some similar bite marks on proboscidean and chalicothere postcrania. Seeing as this is my first published article, I'll go a bit more in depth this time and post this in two or three parts.

The story starts on Christmas day, 2008. As I've alluded to before, winter is one of the best times to go out to the coast and do fieldwork. I suffered through some pretty intense, cold, biting weather this winter - I do not advise wearing hiking sandals on the beach and crossing streams in 45 degree weather with 40mph wind. That hurts. Anyway, now I'm rambling. I left our annual (gigantic) family Christmas dinner in Marin County and went to bed early, planning to take advantage of a favorable tide the day after Christmas. While out on the coast, I saw a boulder of a shellbed that is not normally accessible that had fallen on the beach, and a cute little brown object sticking out of it. Enough was exposed to identify it as a radius (forearm bone) of a juvenile fur seal. The specimen is tiny, and is only 69mm in length; this specimen, however, is lacking the proximal and distal ("elbow" and "wrist" ends of the bone, respectively) epiphyses (epiphyses are the ends of long bones which at birth are unfused, and fuse onto the middle 'shaft' of the bone later in life; the joint they fuse at is sometimes called the 'growth plate', and the fusion of epiphyses is what results in the decreased number of bones in adults relative to the higher number of bones in infants).

The fossil fur seal radius, UCMP 219009, in lateral (left), medial (center), and a magnified image of the bite mark (right).

When I prepared the bone from the soft shelly sandstone later that evening, I found a strange hole on the medial (medial means the side fo the radius closer to the body) side of the bone. This hole had a ring fracture around it, and a depressed ring of the bone's surface was adjacent to the hole itself. Pushed down into the hole was a fragment of the bone surface that had formerly occuppied the middle of the hole. Most importantly, when I prepared this fossil, there was sandstone filling in this feature, and because I was very careful and collected the bone in a block of sandstone, I knew that I had not damaged the specimen, and that this feature had not been formed after fossilization (i.e. it could not have been damaged when it was exposed, because the side with the puncture mark was embedded in sediment). Additionally, there were no hard objects such as a pebble or a shell that could have been pushed into the bone surface - sediment becomes compacted after burial, due to the immense pressures induced by trillions upon trillions of tons of rock overhead. Diagenetic compaction could push a pebble or an invertebrate shell into the bone surface and cause a similar puncture mark. Incidentally, bone can as well - a cranium of Herpetocetus bramblei I am working on describing with Jonathan Geisler has a similar puncture to those reported here, but the end of the jugal bone actually was lodged into the hole, probably as a result of diagenetic compaction. That would make a great paper, too, come to think of it...

Needless to say I was pretty confused at first, and I held off on interpreting it immediately, until I had read some more literature in order to come to a more informed decision on what I thought it was. I've written enough for now, so I'll continue this in a following post.

See also: Dr. Alton Dooley's blog post about this and other bite marks at Updates from the Vertebrate Paleontology Lab.

Boessenecker, R.W. and F.A. Perry. 2011. Mammalian bite marks on juvenile fur seal bones from the late Neogene Purisima Formation of Central California. Palaios 26:2:115-120. Abstract. Paper at Bioone.org.

New article in Palaios

2011-01-23T19:47:00.002-07:00

New articles will be coming soon. I've spent the week and a half since I've been back in Montana recuperating from a moderate case of poison oak, writing major revisions for an article about Pliocene pelagornithids from California (for JVP, with N. Adam Smith), and completing revisions for an article on nonmammal vertebrates from the Purisima Formation (for PalArch's Journal of Vertebrate Paleontology).

Anyway, sometime in the next week or two, the February issue of Palaios will be published, which includes one of my first published articles: Mammalian bite marks on juvenile fur seal bones from the late Neogene Purisima Formation of Central California, by myself and Frank Perry of the Santa Cruz Museum of Natural History.

To view the abstract of the forthcoming article, go here. Once the article comes out, I'll have a less technical summary of it posted here at coastal paleo.

Odontocete skull excavation 2

2011-01-04T13:29:00.017-07:00

Around 4 o'clock in the afternoon along the central California coast, the winter sun gets low on the horizon, giving a few minutes of lengthened shadows and rich, golden light, before it disappears behind a fog bank shortly afterward. The resulting decrease in light marks a premature sunset that can be barely workable sometimes. Winter field work is difficult even in California due to the shortened days, extreme tide fluctuations (even worse in Northern California), stormy weather, muddy trails, and low amount of sand on the beach (which results in a decrease in the number of access points and thus, fewer choices in access route). Oh, and not to mention poison oak, which during the winter, lacks its distinctive leaves). In this case, one of our access points was a small canyon which opens up towards the beach; during the winter, the stream fills the landward side of the canyon up with fetid, organic rich water while waves buildup a barrier bar, which dams the creek and forms a nice, disgusting little lagoon. When we arrived at this locality, the creek had pooled up, and was extremely cold as it had still been in the shade when we got there. The creek water hovered just over freezing, and was a good ten degrees colder than the ocean. It was still just as cold when we left; by the time we were done with the jacket, it was twilight. Oddly enough, on our way out, we came across a couple teenagers going down to the beach (the hard way, staying dry, but going up above the water-filled canyon on the side of a cliff) with only their cellphones for light. They must have made it out safely, although I'm not sure how (I never read in the paper about anyone dying out there).

Here's the excavated pit after the pedestal popped out.

Because the fossil-bearing pedestal had already popped off, we had to place the pedestal on a mound of sand to jacket it.

Chris takes burlap strips back to the excavation. I quite like this photo.

Just before we started the jacketing process. You can see in the background where the hole is, and that just a small sliver of the former 'fairweather' beach was left to stand on in order to reach the fossil. Within a few days, this was all gone. The sand surface you see there (where the red jacket is laying) is the higher surface of the beach from over the summer - just a small remnant of it remains. After this sliver is gone, the fossil would have been many feet out of reach above the beach.

A beautiful sunset (and advancing rainclouds) heralded our completion of the excavation.

The odontocete skull is halfway jacketed, and as the temperature begins to drop, our hands were beginning to go numb.

Chris cuts more burlap strips for the second half of the jacket.

Finally! Just before dark, the plaster jacket is completed, and we're ready to lug all the gear and fossils back up the trail.

Odontocete skull excavation 1

2011-01-03T11:00:00.001-07:00

Over Thanksgiving break in 2009, while scouting out a locality for a future permit application, I spotted a nice braincase of a small odontocete skull exposed in a cliff face. The following november, I received a permit, and returned to the locality one year later with my friend Chris Pirrone to excavate the fossil. I knew this excavation would be slightly challenging, because we would be pedestaling the fossil sideways instead of from the top (I have done worse before - I have successfully trenched and pedestaled fossils in overhangs, including an odontocete skull).

Chris excavating the cranium.

Chris excavating later in the morning.

The skull by midafternoon.

By the middle of the afternoon, we had excavated a ring shaped hole around a cylinder of rock which contains the skull. A few pieces broken off (and glued back on) indicated that the skull was very well preserved. However, given the remaining amount of rock, I was concerned that we would not be able to finish before 5pm. Additionally, while excavating on the left side of the hole, I split off a piece of rock which contained a fragment of the rostrum. This indicated the rostrum was relatively long - a scary prospect, perhaps meaning I would have to return and finish the excavation the following day.

Here's the posterior braincase exposed: the right side of the skull is exposed, and the skull is upside down. The right squamosal, and occipital condyle are clearly visible in this photo.

After continued trenching around the cylinder of rock, at about 4pm, the base of the pedestal snapped unexpectedly, and the whole thing came out in one fifty pound piece. The anterior end of the pedestal terminated against an oblique fracture surface; I was nervous that the rostrum may have continued through this fracture. I carved off a half-inch from this surface, and found no bone; additionally, I found no bone in the end of the pedestal. Fortunately, this means the entire skull is preserved within the block.

Associated dolphin vertebrae

2011-01-01T13:02:00.006-07:00

Sorry for the delay in posting; I've been enjoying a lazy winter break so far. Over thanksgiving break, I spent some time at a Purisima Formation locality which I had just received a new collections permit for. I went out with my friend Chris Pirrone to this new locality. Unfortunately, there hadn't been much storm activity since the summer. Storm activity achieves two things: it washes off a ridnd of weathered clay minerals off (in addition to algae), and it transports sand from the beach to offshore bars, which during fairweather, are slowly eroded and the sand is transported back onshore.

After a while of not finding anything, I spotted these three associated vertebrae - from some kind of a small odontocete. Two of the vertebrae lie in near articulation, and the other is slightly displaced.

Here's a closeup view of the specimens.

Chris Pirrone applies vinac to the fossil vertebrae.

We collected these three vertebrae, but it was too cold to stay and dig through the sediment for more bones. I'm sure there are more; some forelimb or cranial elements would be great. I'll return to the locality once some more storm activity cleans off the cliff exposures.

During the course of my taphonomic research of fossil vertebrates in the Purisima Formation, I've found that associated vertebrate remains (two or more elements which in life are only joined by soft tissue) are extremely rare in the shallow marine fossil record (if the Purisima Formation is taken to be a representative shallow marine deposit). Indeed, this is one of a couple dozen specimens showing any degree of association or articulation.

New updates, soon!

2010-12-14T17:46:00.002-07:00

Hey Folks,Sorry for the delay - just to show you that I have actually been busy and not just lazy, is a picture taken during fieldwork over the Thanksgiving holiday. This was actually taken on Black Friday. More on this story in a few days, after I finish (and hand in) a draft of my thesis (which I have been working diligently on).

At long last: a new skull of Herpetocetus bramblei

2010-11-17T01:30:00.005-07:00

A while ago I posted about some fieldwork I did over the summer regarding a brand new skull of Herpetocetus bramblei. For those of you cetaceophiles, I'm posting pictures of the partially prepared new specimen. As previously mentioned, I suspected the rostrum was offset by quite a bit. Turns out I was right, and it is really offset.
This is after approximately forty hours of preparation, over about two months. I've been really busy working on all sorts of things, including my thesis, and preparation has been going slow. Also, preparation is slightly more difficult due to the much finer sediment - its sandy siltstone - which is hard when dry and easily scraped when damp, although it dries out really, really quickly.

You'll notice a bunch of other offset portions - alas, the skull is a bit more chopped up than I would prefer. That being said, it does look pretty damn cool. All the small fractures and microfaults are left-lateral (sinistral).

The fractures and their relative movement.

I decided to palinspastically restore the rostrum of this skull using photoshop; in addition to left-lateral movement, there's some vertical axis rotation in some of the blocks, so I had to play around with that a bit. Anyway, here's what the complete thing should look like.

And here it is for comparison with my other skull, which is quite a bit larger; I think this new one is from a juvenile. They are reduced to roughly the same size here. In fact, it looks like I could have made the new specimen a bit larger. Herpetocetus has a pretty long schnoz, that's for sure. That's not terribly surprising, given what we know about Piscobalaena.

Shark-bitten dolphin skull

2010-11-12T02:55:00.004-07:00

In 2008 I spent the day before Christmas Eve shivered on a cold, wind-blasted California beach prospecting for vertebrate fossils in the Purisima Formation. I was home on winter break, and although it is far more cold where I go to graduate school in Montana (as I write this I'm looking out at the results of our first winter snow), nothing is worse than being wet and miserably cold out on the foggy, windy coast of the golden state (except perhaps being wet and miserable on the Oregon coast, which I've done).

The thrill (or promise) of discovery is more than enough to keep me fueled in the field during the winter. Indeed, when the birds start singing and the snow melts in the spring, most paleontologists start to get field fever - the field season for most vertebrate paleontologists is during the summer months. Anyone who's ever tried to do coastal fieldwork during the summer, on the other hand, is in for a rude awakening. No erosion takes place during the summer, and many of the outcrops are totally buried. The exposures that are above the beach sand level (which is higher during the summer) are typically covered with dust, sand, and grime, which obscures fossils. The storms in the winter months clean this nasty coating off, and transport beach sand into offshore bars, often exposing strata below the beach (I see new fossil localities every winter this way). Winter is my field season.

Historically, I've had really good luck the day before Christmas Eve. It's my last day before Christmas to make it out in the field. The prior year, I found a humongous Carcharocles megalodon tooth (the only specimen known from the Purisima Formation), and discovered a partially articulated fur seal skeleton.

The Christmas Eve dolphin.

At 4pm, the tide was beginning to come back in, and with little over an hour of daylight, it was looking like I was going to come home empty-handed. I went to one last cove before I turned around to head back to the beach. I walked for a few minutes and spotted something in a boulder I had not seen on my way out: a pair of flat bones joined along an articulation that looked suspiciously (even from 20 feet away) like the palate of a dolphin skull. Upon closer examination, yes indeed! It was a dolphin skull in a mollusk shell bed; the width and flatness of the palate suggested it was not Parapontoporia, the most common odontocete in the Purisima Formation. I set about chopping into the boulder; fortunately, most of it was relatively soft. However, an extremely hard calcium-carbonate cemented concretion the size of a basketball had formed over the dorsal surface of the braincase and rostrum, and this slowed digging down. By dusk, the concretion didn't budge. After another half hour, it finally popped out of the boulder, and I lugged the 45 pound block back to my car. Exhausted, I drove home, drank a couple of hard-earned beers with dinner, and passed out.

View of the facial region of the skull.

When it came time to go back to Montana, I decided I would rather take the fossil as a carry-on than risk checking it and picking up a broken fossil that I had paid 25 bucks for thanks to baggage fees. After arriving in Bozeman (with a very sore back and neck from lugging 65 pounds

of luggage through the Denver airport), I almost immediately began preparation (starting, of course, with acetic acid baths for several weeks to soften the concretionary matrix). It took about two months to prepare, and as you can see from the above photos, it is damn beautiful. I initally identified it as something like Haborophocoena - it bears numerous similarities. However, after showing them photos of the specimen at SVP 2009 in Bristol, UK, Olivier Lambert and Giovanni Bianucci both think this represents a basal delphinid rather than a basal phocoenid. I'm inclined to agree with them, although part of my original ID was based on the presence of premaxillary eminences, which this specimen has (a phocoenid character). However, the ascending process of the right premaxilla is in contact with the nasals while the left is not (a delphinid character). Whatever it is, it will require preparation of the ventral aspect, and more careful analysis of the morphology than what I've been able to do thus far. Whatever it is, it appears to represent a new genus and species, and will make a beautiful holotype specimen in the future. During preparation, one curious thing I noticed was a notch in one of the premaxillary eminences (the large pads/bumps in front of the bony nares). I initially dismissed it as a pathology.

The left premaxillary eminence showing linear gouges (red lines) and missing bone.

Upon closer examination (which admittedly did not occur until yesterday, almost two years after collection) it became apparent that the abnormal area had two distinct, paralell linear gouges, and a short, less distinct third one in the middle (this one is still partly filled with matrix). Around these gouges is an area of exposed cancellous bone, where the bone has been removed.

Additional gouges present near the base of the rostrum.

I also found four more gouges present: two long ones, and two short ones; all but one are parallel. In fact, aside from the one gouge seen above trending towards the upper left corner of the photo, all the gouges are parallel. This is a textbook set of shark-inflicted bite marks. There are a lot of papers on this in the literature, documenting shark bites on dolphins, baleen whales, pinnipeds, sea turtles, other shark teeth, mosasaurs, plesiosaurs, dinosaur bones, sea stars, and probably other marine critters as well.

In fact, the first record of these types of trace fossils were actually first documented in the modern environment: on predated and scavenged sea-otter carcasses from Monterey Bay, and reported by Ames and Morejohn (1980). The reported linear gouges, subparallel wavy small gouges, and a specimen including a shark tooth embedded in a sea otter skull. The morphology of the traces along with the tooth identified the culprit as the Great White Shark, Carcharodon carcharias. Two years later, these exact types of traces were identified by Tom Demere and Richard Cerutti (1982) on a baleen whale dentary (of my favorite whale, Herpetocetus!), and identified as "Carcharodon sulcidens" (a taxon now just considered to be fossil Carcharodon carcharias).

It's not clear what type of shark fed on my poor little dolphin, or if it was a case of predation or scavening; from what I've read, the majority of carcasses that exhibit bites have bite marks on the posterior portion of the body, which is just about as far as you can get from the face. This makes total sense, given how a shark would have to bite into a fleeing dolphin during pursuit. Furthermore, it's interesting to note that this bite would have had to go clean through the dolphin's melon (if it had not already decomposed). Anyway, I interpret these traces as drag marks from the apices of the shark's teeth; I suppose later on I can figure out the relative motion of the shark's mouth during the bite (most likely lateral shake feeding). It'll make for a nice short paper some day...

Ames, J. A., and Morejohn, G.V., 1980, Evidence of white shark, Carcharodon carcharius, attacks on sea otters, Enhydra lutris: California Fish and Game, v. 66, p. 196-209.

Deméré, T.A., and Cerutti, R.A., 1982, A Pliocene shark attack on a cetotheriid whale: Journal of Paleontology, v. 56, p. 1480-1482