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

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.

...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

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

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

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

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!

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