An Eocene pinniped? A critique of Diedrich (2011)

Several months ago I was kindly asked by Dr. Cajus Diedrich to remove this post. I have edited certain parts for content. Following the mantra that "extraordinary claims require extraordinary evidence", I've decided to leave the post up to inform those interested in fossil pinnipeds with a series of critical comments and observations regarding the "Eocene" seal. -R.W. Boessenecker, 11/28/2012

While I was in Montana enjoying my first christmas vacation with my in-laws, I got an email with an attached pdf of a new paper that had just been published. I had expected quite a bit of time to get some work done -after all, my wife and I were up there for a week and a half and her parents would be at work much of that time - and the weather was too poor to go and do anything outside. I had already expected to get some reading and writing done, so I was pleased to hear of the new publication. Once I saw the title page, though, I was immediately skeptical, and indeed - my skepticism did not go away once I was finished with the article. The title of the article was "The world’s oldest fossil seal record", and the abstract indicated that an Eocene seal - not just any pinniped, but a phocid seal - had been discovered in Germany. I was not familiar with the author, Cajus Diedrich, whose previous work has focused on other groups (Pleistocene carnivores, Triassic marine reptiles) - but I did remember reading an article by him revising placodont (you remember, those funky sauropterygian marine reptiles with big crushing teeth) paleoecology, suggesting that most placodonts were Triassic analogs of sea cows.

The skeleton of the dawn seal, Enaliarctos - the oldest known
bona fide pinniped. From Berta et al. (1989).

Before I go any further, I should summarize why exactly one should be skeptical of an Eocene pinniped. For starters, the majority (either by taxa or number of specimens, ~99%) of fossil pinnipeds are from the Miocene or younger strata. There are a handful of bona fide pinnipeds from the late Oligocene, though, which are represented by skulls. These include Enaliarctos tedfordi from the Yaquina Formation of Oregon (~28-25 Ma), and Enaliarctos barnesi from the uppermost Yaquina Formation or lowermost Nye Mudstone (~26-23 Ma, also Oregon). There are a bunch of other species of Enaliarctos known from the early Miocene and roughly 20-25 Ma in age, including Enaliarctos emlongi from near the Nye Mudstone-Astoria Formation contact in Oregon, Enaliarctos mitchelli (early Miocene Jewett Sand of California and Nye Mudstone of Oregon), and Enaliarctos mealsi from the Jewett Sand. Slightly younger fossil assemblages from the Astoria Formation, further upsection in the Newport Basin of Lincoln County, Oregon, show a mix of "enaliarctine" pinnipeds (Pteronarctos, Pacificotaria), two species of Desmatophoca, an early 'allodesmine', and the dawn walrus Proneotherium (Barnes, 1989; 1990; 1992; Barnes and Hirota, 1995; Kohno et al., 1995). Note that during the early Miocene in the North Pacific, yes - pinnipeds first start to diversify and different groups (e.g. non-"enaliarctines"), but most of these are either "enaliarctines", members of a wholly extinct clade (Desmatophocidae), or extremely archaic and "enaliarctine"-like members of extant clades (Proneotherium).

The femur of the dawn seal, Enaliarctos. This is Enaliarctos emlongi
from Oregon. From Berta (1991).

In other words, there aren't any crown-clade pinnipeds anywhere close to the Oligo-Miocene boundary. In the North Atlantic, the oldest known pinniped with diagnostic remains is Leptophoca from the middle Miocene Calvert Formation of Maryland, crania of which were described by Koretsky (2001). In fact, this is the oldest bona-fide and widely accepted record of fossil phocids. Irina Koretsky and Al Sanders published a paper in 2002 about partial fossil femora reputedly from the late Oligocene of South Carolina (I have discussed these specimens elsewhere). To summarize - these fossils are roughly 10 Ma older than Leptophoca and were presented as being 1) the oldest fossil phocids, and 2) evidence for pinniped diphyly. For the uninitiated, there have been several morphological hypotheses for pinniped evolution, and the diphyletic view states that true seals (Phocidae) are related to mustelids/musteloids, and sea lions (Otariidae) and walruses (Odobenidae) form a monophyletic clade (Otarioidea) and share a common ursid-like ancestor, having adapted to water separately from phocids. I won't go into it now, as the Eocene seal is totally separate from diphyly/monophyly. There are several problems with Koretsky and Sanders (2002) - 1) they did not examine femora of other Oligocene terrestrial mammals, and 2) the stratigraphic provenance of those specimens are questionable (see here for more on this). To summarize: late Oligocene pinnipeds consist of only a few diagnostic fossils from the North Pacific, and modern "family" level clades do not appear until a ways into the Miocene.

The femora of the alleged Oligocene seal. From Koretsky and Sanders (2002).

Phew, now that the introduction is done, I can talk about the paper. Diedrich (2011) published a partial, proximal femur fragment (just like Koretsky and Sanders 2002), from the Fürstenau Formation of Northern Germany, which is a Lutetian age shallow marine unit deposited on the southern margin of the pre-North Sea basin, roughly 45-49 Ma in age. So, we're not even talking latest Eocene and bordering on Oligocene - this is early middle Eocene, about 5 Ma before basilosaurids show up, just before protocetids evolve. The fossil itself is phosphatized and exhibits several borings, is missing the distal end, and has clearly been reworked (for the uninitiated: phosphatization can only occur on bones or sediment below the sediment-water interface, so a bone that is both phosphatized and abraded or polished by default has been reworked). It does look remarkably phocid-like: it lacks a fovea capitis for the teres ligament - a little pit on the femoral head. It also appears to genuinely lack a lesser trochanter (as opposted to being abraded or broken off) and is very anteroposteriorly flattened. All of these features are phocid or pinniped characteristics; the lack of a fovea capitis is a probable pinniped synapomorphy (Berta and Wyss, 1994). A lesser trochanter is absent in all modern and fossil phocids and the modern walrus, but present in all fossil walruses and modern and fossil otariids. Interestingly, these are all the same features listed by Koretsky and Sanders (2002) to identify their femora from the Oligocene of South Carolina. I'm not sure that erecting the name Praephoca bellunensis for this fragment of an element with dubious diagnostic utility was prudent.

The holotype femoral fragment of Praephoca bellunensis, the alleged
Eocene seal. From Diedrich (2011).

So far so good. When oddball fossils like this crop up - ones that just smell fishy - the best thing to do is to see if something could have gotten seriously screwed up between it leaving the ground and entering the annals of a journal. Reading the Materials and Methods, it goes through a long description of the large excavation conducted at Dalum, Germany, where the Fürstenau Formation is exposed. Buried toward the end of the Materials and Methods section, I found this:

"The femur illustrated in Figure 2 was actually found was actually found in these gravels during the 1980s, and has prompted a major program seeking to understand the biodiversity of marine vertebrates in Europe during the Eocene, in relation to that of the terrestrial vertebrates. This femur, together with all material from the 2011 excavations, is housed in the Shark Center at Bippen (SCB) in northwest Ger-many, a public visitor center and museum in the UNESCO- supported “Geo and Naturpark TERRA. Vita”."

So, it sounds like this started with the discovery of the fossil femur 25-30 years ago, and then the excavation was undertaken in May 2011. Who collected the fossil originally? I just don't know. Whoever it was - especially if was an amateur collector unfamiliar with local stratigraphy - do we know that they were able to positively remember the exact locality and horizon at which the fossil was collected? 25-30 years is a long time - and people often have unreliable memories, which is why most scientists can't afford to not write important things down. I have also met collectors who have admitted to intentionally making misleading statements to researchers about the locality and provenance of certain specimens, and I've met collectors who can't remember what they collected last week. To be clear, I know many collectors who know local stratigraphy very well and remember the exact location, time, date, etc. of a fossil collection. The same variable quality of memory exists within paleontologists - which is why we really must write everything down. To summarize, the stratigraphic provenance is poor, and it is not clear if the fossil really came from that locality or not. Secondly: the fossil is reposited at the "Shark Center at Bippen". Look it up - the only results are the pdfs of Diedrich's articles. I'm not sure where this place is, or who runs it.

Modern pinniped femora (from right to left - walrus, California sea lion, and harbor seal), arrow showing the position of the lesser trochanter. While it is reduced and absent in the modern walrus, it is present in nearly all fossil walruses for which femora are known (e.g. Imagotaria, Gomphotaria, Valenictus, Proneotherium).

An additional bit of interesting contextual data is a paper published on the results of the May 2011 excavation (Diedrich 2012), which yielded 13,690 shark teeth (!!!!), 206 ray teeth, a handful of other marine vertebrates, and two indeterminate mammal bones. Not even a single isolated seal tooth; my own field collecting suggests that you should find a tooth for every 5 pinniped bones or so, and perhaps a pinniped bone for every 10 shark teeth (Purisima Fm. data from my still unpublished Master's Thesis). So, where are they? There should have been hundreds of phocid fossils, and there aren't even any cetacean bones (probably because it's too old for archaeocetes; only a couple of protocetid and remingtonocetid specimens are known from Europe, and it's too early for basilosaurids). Cetaceans are almost always more common than pinnipeds in any given marine assemblage. It just doesn't add up.

Cladogram with fossil-calibrated molecular divergence dates, modified from Fulton and Strobeck (2010). This study isn't perfect by any means (and warrants further discussion on this blog), but is a hell of a lot closer to the mark than what Praephoca would do to this cladogram.

Another line of evidence are molecular divergence dates for pinnipeds, and the "fissiped" carnivoran fossil record. The most recent molecular divergence dates published by Fulton and Strobeck (2010) suggest an Oligo-Miocene divergence of basal pinnipeds (this is, however, based on Enaliarctos as a fossil calibration). The pinniped + mustelid divergence is in the latest Eocene, and the caniform divergence occurs just earlier in the early-middle Eocene. The earliest true carnivorans don't even appear until the Eocene, and the earliest possible Caniformia appear about 42 Ma - about 3 Ma after this alleged seal fossil. Purported pinniped sister taxa like Amphicticeps, Amphicynodon, Pachycynodon, and Allocyon don't show up until the Oligocene; apparently more pinniped-like taxa like Kolponomos and Puijila aren't even in the picture until the earliest Miocene. Just on grounds of parsimony, given the ranges of these other taxa - this record should be considered suspect. Accepting Praephoca at face value, and putting it into a phylogeny would 1) telescope nearly all cladogenesis within the Caniformia ~30 million years earlier than previously thought, and 2) add dozens of ghost lineages for nearly every caniform clade across the entirety of the Oligocene and halfway across the Eocene, at that. Where are all the fragmentary scraps of the dozens of other crown-clade carnivorans in the early Eocene? They just don't exist, although they would be a natural consequence of having phocids in the Eocene.

On the other hand, I am glad that the study got published, because it gives us something interesting and controversial to talk about it - just as long as molecular systematists don't take it too seriously. This is a nagging worry, as I've seen in happen before (e.g. the Milinkovitch 1993 hypothesis, which I will talk about another time). In all seriousness - there are a number of problems with the work of Diedrich (2011), and should not be taken at face value. Extraordinary claims require extraordinary evidence - a busted up femur that may or may not be from a phocid seal and may or may not have been collected at the same site which later produced nearly 14,000 vertebrate fossils and not a single other pinniped element is not extraordinary evidence. 

References/further reading:

L. G. Barnes. 1989. A new enaliarctine pinniped from the Astoria Formation, Oregon, and a classification of the Otariidae (Mammalia: Carnivora). Contributions in Science 403:1-26

L. G. Barnes. 1990. A new Miocene enaliarctine pinniped of the genus Pteronarctos (Mammalia: Otariidae) from the Astoria Formation, Oregon. Contributions in Science 422:1-20

L. G. Barnes. 1992. A new genus and species of middle Miocene enaliarctine pinniped (Mammalia, Carnivora, Otariidae) from the Astoria Formation in Coastal Oregon. Contributions in Science 431:1-27

L. G. Barnes and K. Hirota. 1995. Miocene pinnipeds of the otariid subfamily Allodesminae in the North Pacific Ocean: Systematics and relationships. The Island Arc 3:329-360

Berta, A. 1991. New Enaliarctos* (Pinnipedimorpha) from the Miocene of Oregon and the role of "Enaliarctids" in Pinniped Phylogeny. Smithsonian Contributions to Paleobiology 69.

A. Berta. 1994. New specimens of the pinnipediform Pteronarctos from the Miocene of Oregon. Smithsonian Contributions to Paleobiology 78:1-30

C. Diedrich. 2011. The world's oldest fossil seal record. Natural Science 3(11):914-920.

C. Diedrich. 2012. Eocene (Lutetian) Shark-Rich Coastal Paleoenvironments of the Southern North Sea Basin in Europe: Biodiversity of the Marine Furstenau Formation Including
Early White andMegatooth Sharks. International Journal of Oceanography doi:10.1155/2012/565326

T. L. Fulton and C. Strobeck. 2010. Multiple fossil calibrations, nuclear loci and mitochondrial genomes provide new insight into biogeography and divergence timing for true seals (Phocidae, Pinnipedia). Journal of Biogeography 37:814-829

N. Kohno, L. G. Barnes, and K. Hirota. 1995. Miocene fossil pinnipeds of the genera Prototaria and Neotherium (Carnivora; Otariidae; Imagotariinae) in the North Pacific Ocean: Evolution, relationships and distribution. The Island Arc 3:285-308

I. Koretsky. 2001. Morphology and systematics of Miocene Phocinae (Mammalia: Carnivora) from Paratethys and the North Atlantic region. Geologica Hungarica Series Palaeontologica 54:1-109

Koretsky, I.A. and A.E. Sanders, 2002. Paleontology of the Late Oligocene Ashley and Chandler Bridge Formations of South Carolina, 1: Paleogene pinniped remains; the oldest known Seal. Smithsonian Contributions to Paleobiology 93: 179-183.

Rybczynski, N., Dawson, M.R., Tedford, R.H. (2009). "A semi-aquatic Arctic mammalian carnivore from the Miocene epoch and origin of Pinnipedia". Nature 458 (7241): 1021–24

R. H. Tedford, L. G. Barnes, and C. E. Ray (1994). "The early Miocene littoral ursoid carnivoran Kolponomos: Systematics and mode of life". Proceedings of the San Diego Society of Natural History 29:11-32.

X. Wang, M. C. McKenna, and D. Dashzeveg. 2005. Amphicticeps and Amphicynodon (Arctoidea, Carnivora) from Hsanda Gol Formation, Central Mongolia and phylogeny of basal arctoids with comments on zoogeography. American Museum Novitates 3483:1-57

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

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)

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

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.

Dead baby fur seals at the California Academy of Sciences

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.