Another "new" publication: pilot whale-like delphinids from the Purisima Formation

The second paper that I published this year (freely available online here at App.pan.pl), and did not get around to discussing on this blog, was a paper I published with Frank Perry (Santa Cruz Museum of Natural History) and Jonathan Geisler (NYIT College of Osteopathic Medicine) in Acta Palaeontologica Polonica. This study reported some new fossils of Pliocene globicephaline whales from the Purisima Formation near Santa Cruz. Generally, most papers I have published are concerned with fossils I’ve dug up myself, with a few exceptions – this being one of them. In summer 2009, I received a forwarded email from Frank Perry including some photographs of a fragmentary odontocete skull in a partial concretion. Frank (at first) was not excited, but I was puzzled at the relative size of the scale bar – it was one of those clear plastic rulers made for kids, and after looking at the whole image at large size, I noticed that it was not a 6” ruler, but a 12” ruler – indicating the preserved fragment was about a foot and a half long (~40 cm). This was no porpoise or small dolphin – this was something big, pilot whale or beluga sized – a substantial beast indeed. 

The prepared fossil globicephaline skull from the Purisima Formation, collected by Robin Eisenman in 2009 from the shore of Monterey Bay. From Boessenecker et al. (2013).

I emailed Frank about this, who gave me the contact information for the collector – Robin Eisenman, then of Aptos – who after only a few minutes on the phone happily agreed to contribute the fossil to science. So, I picked it up, and took it back to Montana State University to prepare it. Preparation did not take long, owing to great separation of the rock from the bone. On a subsequent visit back home, I drove down to Watsonville to check out the collection of Stan Jarocki, a dedicated amateur paleontologist with one of the best eyes for finding fossils I’ve ever come across, professional or otherwise. I’ve been in the field several times with Stan, and every time it’s amazing what he’s able to pull out from just a couple square millimeters of exposed bone. Stan is perhaps best known for establishing a rather large collection of bird fossils from the Purisima Formation, including numerous beaks and braincases, not to mention prized complete humeri and other diagnostic postcranial bones. I was quite amazed to see the first drawer in his collection, which was an entire drawer filled with nothing but dolphin ear bones -  baleen whale ear bones were in a separate drawer. Among these new finds were several Herpetocetus periotics which he permitted me to take for donation to UCMP and study, in addition to a neonatal or perinatal partial mandible of Herpetocetus; these specimens will be described in detail whenever I get around to writing up my Purisima Herpetocetus research. In the dolphin ear bone drawer I saw dozens of periotics which were obviously the “river” dolphin Parapontoporia, various phocoenid periotics, and several delphinine periotics (often identified in the literature as “Delphinus or Stenella”). Among the phocoenid periotics, two looked superficially similar to a phocoenid mentioned by Larry Barnes in his Ph.D. dissertation as “aff. Tursiops” which is now known to be a Haborophocoena-like phocoenid with an asymmetrical skull – but were much, much larger. I looked at them, and concluded they must be some sort of large delphinid.

The skull in lateral and posterior view, with a line drawing of endocast features. From Boessenecker et al. (2013).

Now, at first I didn’t know what the skull represented – I thought it was some sort of massive monodontid, something a bit weirder and larger than the pilot whale convergent monodontid Denebola brachycephala. It wasn’t until I was flipping through the plates of Van Beneden and Gervais (1880) – one of the great cetological monographs – that I realized that the skull was a good match for a globicephaline whale. Not too long after this, I contacted Jonathan Geisler, and proposed we present it as a poster at the 2009 SVP meeting – which I presented at the Bristol meeting of SVP, and if you look at the abstract, it says we identified it as Globicephala sp. We eventually decided it wasn’t referable to the genus, but certainly the subfamily. The fossil exhibits some features distinctive to the subfamily, such as large size, anteriorly widening premaxillae, and premaxillae that slope medially on the base of the rostrum; however, the development of a longitudinal ridge on the premaxilla precluded referral to any extant globicephaline. Furthermore, the ventral side of the skull actually had some features that were more like Pseudorca than Globicephala, something that Jonathan Geisler and I found out on a visit to the AMNH in January 2011.

The two globicephaline periotics collected by Stan Jarocki from the Purisima Formation in Santa Cruz County. From Boessenecker et al. (2013).

On a short tangential side note, Jonathan Geisler had invited me to contribute to a webpage on the NYCOM (Now NYIT College of Osteopathic Medicine) website about cetacean evolution – but due to a quirk in New York laws, I’d have to fly out to Long Island and sign everything in person. So, Jonathan graciously paid for me to fly out, sign the paperwork, and hang out in New York for a week – including a day trip to the AMNH. Even though it’s only a one hour drive from Manhattan, it took us two hours by train and subway to get there from NYIT. Upon arriving from my flight and getting a cab ride to Old Westbury (the driver had no idea where it was, and it took him until 30 minutes into the drive to figure out where it was) – two pieces of bad news presented themselves. The first was that I had been rejected from the SDSU-UCR joint doctoral program; the second was that I had taken the globicephaline fossil with me, and it had broken in transit. I noted that it would be an easy fix, but still… talk about circumstance kicking someone when they’re down.

Bivariate plot of promontorium length and maximum width of bony nares for Delphinida (based on adult crania), with horizontal line for the skull, and vertical lines for the two periotics. This indicates that the periotics are probably too small to belong to the same taxon as the skull, and that two globicephalines are recorded in the Purisima Formation. From Boessenecker et al. (2013).

So, enough with the backstory, time for some more science. After examining the two periotics that Stan Jarocki collected, Jonathan noted that they appeared a bit on the small side to go along with the skull that Robin Eisenman collected – which got him on to thinking that there may have been two separate globicephalines preserved in the Purisima Formation. In order to evaluate this, Jonathan used a bunch of measurements that he had amassed as part of an NSF funded project on delphinidan phylogeny. He used two measurements in particular: external bony nares width, and the length of the promontorium. When these measurements for fossil and modern delphinidans are plotted on a graph, a distinct trend can be seen – although there is quite a bit of scatter around the line of best fit. Regardless, the results do indeed suggest that the periotics are far too small to represent the same globicephaline as the skull: using the line of best fit, the skull size (narial width = 110mm) would be associated with periotics that had a 21mm long promontorium on the periotic, and the periotics instead have ~15mm long promontoria, which would be associated with a skull approximately half the size (narial width = 60mm). This line of evidence suggests that there were indeed two globicephalines present in the Purisima Formation. Interestingly, this is one of the only localities in the Pacific realm to include more than one globicephaline.

Geographic distribution of late Miocene, Pliocene, and Pleistocene fossil globicephalines. Black denotes described or figured specimens. From Boessenecker et al. (2013).

Lastly, we reviewed the globicephaline fossil record, and found that the subfamily was already worldwide in distribution by the early Pliocene. Molecular divergence date estimations for the clade include estimates as old as 8 Ma (Vilstrup et al., 2011) and as young as 4 Ma (McGowen et al., 2009). Few globicephalines are any older than 6 Ma, and the late Miocene is one of the most intensely sampled parts of the cetacean fossil record; we suggested that divergence dates as old as 8 Ma are probably too old, and likewise by 4 Ma we already have globicephaline fossils – indicating that 4 Ma is certainly too young. Divergence dates of about 5.5 Ma (Cunha et al., 2011) are probably more accurate. Discovery of additional (and better preserved) globicephaline fossils will help refine this picture.

References

Boessenecker, R.W., Perry, F.A., Geisler, J.H. 2013. Globicephaline whales from the Mio-Pliocene Purisima Formation of central California, USA. Acta Palaeontologica Polonica.

Cunha, H.A., Moraes, L.C., Medeiros, B.V., Lailson-Brito, J. Jr., da Silva, V.M.F. 2011. Phylogenetic status and timescale for the diversification of Steno and Sotalia dolphins. PLoS ONE 6 (12): e28297.

McGowen, M.R., Spaulding, M., and Gatesy, J. 2009. Divergence date estimation and a comprehensive molecular tree of extant cetaceans. Molecular Phylogenetics and Evolution 53: 891-906.

Vilstrup, J.T., Ho, S.Y.W., Foote, A.D., Morin, P.A., Kreb, D., Krützen, M., Parra, G.J., Robertson, K.M., Stephanis, R. de, Verborgh, P., Willerslev, E., Orlando, L., Gilbert, M.T.P. 2011. Mitogenomic phylogenetic analyses of the Delphinidae with an emphasis on the Globicephalinae. BMC Evolutionary Biology 11:65: 1-10.

A "new" publication: sea lions, barnacles, and taphonomy - what can encrusting invertebrates tell us?

Earlier this year I had two papers published which I never really had time to talk about on here. The first of them was published in the July issue of the Journal of Paleontology, and regards fossil barnacles preserved on sea lion bones from the Pleistocene of Oregon. The second – published a bit later in Acta Palaeontologica Polonica – is about fossil globicephaline dolphins from the Purisima Formation of Northern California.

This paper (viewable online here at Bioone.org) has its origins in June 2008. I had just completed my last semester of my undergrad geology program, and had planned an ambitious week of fieldwork along the coast of Oregon and Northern California. Some of these localities included the Wildcat Group, Moonstone Beach Formation, Falor Formation, St. George Formation, and the Port Orford Formation. I arrived at the first locality, located in Curry County, Oregon, after 16 hour drive to Eugene from Montana, and a short drive out to the coast. I knew of the locality from a paper by Larry Barnes on a new genus and species of sea lion, which had been collected by my idol Douglas Emlong about thirty years prior. I had also read the 1979 Ph.D. thesis of UC Berkeley student Barry Roth, who reviewed an impressive number of Plio-Pleistocene mollusk fossil localities in Northern California and Oregon.

Sunset on the southern Oregon coast.

Upon arriving in the area, I located a campsite and set up a tent for the night – I had planned on spending the night and doing some fieldwork the next day. I trekked down a mile and a half of windswept, desolate coastline; the wind was so strong, I felt pretty exhausted by the time I reached the locality – each step was an effort. Not being used to fossil localites outside of central California, I was expecting a fairly rich fossil site – Emlong had collected a skull, mandible, and a bunch of other bones from here, after all. At many fossil localities in Central California, one can identify dozens of exposed fossil bones within a half hour of arriving. At this locality, it was not so rich; after a few minutes, I did find a complete mandibular cartilage of a skate (Raja), and about ten minutes later, identified a pair of associated bones sticking out of the cliff; I photographed the locality, wrapped the specimens up in newspaper, and secured them in my pack; I was hoping for more. These only appeared to be vertebrae, after all. The fog was getting quite a bit thicker, with visibility down to about fifty feet; I thought it would begin raining soon, so I moved on, deciding to write my notes down later that evening. I headed up into a couple of gullies, and at one point sank nearly up to one hip in a curiously quicksand like mixture of mud and cobbles (it was, in fact, a recently deposited debris flow formed by late Pleistocene cobbles mixed with early Pleistocene muds). Shortly thereafter, it began raining: just great; by the time I made it back to the car I was drenched. After making a phone call to inquire about the weather in Curry County and further south, I found out that it was supposed to be sunny and warm further south in Humboldt County – my next stop. So, I went and packed up my tent, and continued south, escaping the crap weather.

Heading back through the dunes to the car with a full pack, and unbeknownst to me at the time, sea lion vertebrae completely coated with fossil barnacles (May, 2008).

A week later after some largely unfruitful visits to Humboldt County fossil sites (aside from collecting a rare sea otter tooth – Enhydra macrodonta), I was back in the bay area, and unwrapped nature’s fossil presents. I took the lumps of bone-bearing rock and sat them in the driveway, and blasted them with a water hose; after a few minutes, it became obvious that I had a pinniped vertebra. After another minute, I saw numerous barnacles – which appeared to be attached directly to the bone surface! The same held true for the other bone; their closeness in the rock (~20 cm) suggested that they were associated (i.e. originated from the same individual carcass). After a brief search online, I realized that this was fairly significant and that noone had really adequately documented this sort of occurrence before. Encrusting organisms are assumed to be common, but are rarely recorded in the literature; the occasional mentions they receive rarely pass the “Oh, interesting, there’s barnacles on this bone” stage, and few papers have ever inspected the taphonomic implications of encrusting invertebrates in detail. In contrast, documentation of encrusting organisms on invertebrate fossils is excellent, demonstrating that it’s probably a bias against taphonomic research by fellow vertebrate paleontologists (perusing back issues of PPP, Palaios, and Lethaia easily gives the impression that vertebrate paleontologists contribute only about 10% - or less – of taphonomic research in comparison to invertebrate paleontologists).

Dick Hilton (Sierra College) looking for Pleistocene marine mammal fossils (July, 2009). All those little white specks on the ledge are tiny fossil bivalves.

In 2009 I returned to the locality with Dick Hilton, and collected a sea lion femur; at the time I couldn’t see any barnacles, and when I returned to Montana that fall I placed it into a light acid bath as a demonstration for my friend Ash’s fossil preparation class. After a minute or so, I peeked into the violently fizzing bath and saw white flecks poking out of the calcareous sediment; I pulled it out and saw that indeed, this bone was totally encrusted with barnacles, too! After realizing this, I decided that enough was enough, and I spent about three weeks completing prep work over at Museum of the Rockies on the three specimens. Normally, concretions from that locality would have prepared well in acid, but barnacles are composed of the same mineral that made up the cement in the rock – calcium carbonate – which is highly soluble even in weak acetic acid. I’m glad that I pulled the bone out – otherwise I would have checked up on it a day later, and who knows how many barnacles would have been lost. Once the specimens were prepared, I began writing up a manuscript detailing the find and the implications. Although a first draft was completed in 2010, it took a back seat to my master’s thesis (arguably a more important endeavor). After arriving here in NZ last year, I realized that it would only take about a week to complete all the necessary tasks to bring the manuscript to being submission-ready – and accordingly I quickly wrapped the project up and got it submitted (to a separate journal, to which it was eventually rejected by a reviewer with a number of inappropriate and largely irrelevant arguments).

Aha! This is the sea lion femur at the time of discovery. Most of it was covered in a concretion and just a sliver of bone was sticking out.

During my visit last year to the Smithsonian, I examined some material (referred by Barnes et al. 2006 to various otariids) including a Zalophus californianus scapula collected from the same locality. The scapula lacked barnacles, but had a number of attachment scars preserved on it. I edited the manuscript again for submission, and included this “new” specimen in the paper.

The sea lion (Zalophus californianus) scapula which Emlong collected decades before. Image 3 shows the circular barnacle attachment scars.

Sorry for the long intro – there’s a bit of back story, but now that we’re done with that, what exactly were my findings? Three different specimens – two associated vertebrae, a femur, and a scapula – bore evidence of barnacle encrustation. The two vertebrae were encrusted with a total of 1400+ barnacles (I counted them all…), the femur with ~200 or so, and 15 on the scapula. Preserved evidence included actual attached barnacles, attachment scars with incised basal rings, and attachment scars visible only as changes in color (i.e. no physical etching was present). While the vertebrae had barnacles on nearly all surfaces, the femur and scapula only had barnacles preserved on one side. This led me to interpret that the vertebrae must have been overturned regularly, and that the femur and scapula were probably not overturned by currents during the period of barnacle colonization. More interestingly, the barnacles were of various sizes, and some of the smaller barnacles were encrusting larger ones: this implied that at least two phases of larval colonization were recorded in the assemblages. 

The two vertebrae I collected in May 2008, fully prepared as illustrated in the Journal of Paleontology article. 1-3, anterior thoracic vertebra; 4-6, posterior thoracic vertebra; 7, lateral side of neural spine of anterior thoraci; 8, same, but for posterior thoracic; 9, lateral side of centrum of posterior thoracic vertebra.

More important was the species identification of the barnacles. In summer 2010 I had dropped the barnacle encrusted specimens at California Academy of Sciences for barnacle specialist Robert (Bob) Van Syoc to make an identification. Bob identified the barnacles as Solidobalanus hesperius – a species which is still extant; this should not be immediately surprising, as the rock unit they were collected from is approximately 700,000 years in age (not late Pliocene, as erroneously identified by Barnes et al. 2006). The best part about finding modern species in the fossil record is that growth data often exist for them. In fact, one study – published in the early 1980’s in the Soviet Journal of Marine Biology (which, unfortunately, does not follow the lives and habits of Marxist mollusks) – reported age data for the species colonizing the Yesso or Yezo scallop (Patinopecten yessoensis, extant relative of the Pliocene dinner-plate scallop Patinopecten healeyi). These Russian authors found that Solidobalanus hesperius has a lifespan of about 6-7 months, during which it attains a basal shell diameter of about 15mm; over a 4-5 month period, they attain a basal shell diameter of 6-8mm. Most of the shells were smaller than this size range, but many were in the 6-10mm size range, so I used a conservative estimate of 4-7 months using those two endpoints.

As far as I’m aware, this is one of the first (if not the first) paleontologic studies to apply growth data from an invertebrate to determine a minimum period of exposure on the sea floor. I shouldn’t brag, because it’s not a novel concept: this method has been applied before to forensic cases where human remains were recovered from the seafloor with attached barnacles (e.g. Dennison et al, 2004). Regardless, we as taphonomists have a lot to learn from forensic taphonomists: there’s a lot more of them, they’ve been at it far longer than we have, and their work has to hold up in a court of law.

The femur collected in July 2009, fully prepared.

Another aspect of this study is that barnacle produced traces in addition to barnacles were identified on vertebrate remains. Barnacle attachment scars have been known for a long time (see Miller and Brown, 1979), and somewhat recently the circular, rather simple scars reported on these sea lion bones were given the name Anellusichnus circularis by Santos et al. (2005). This study confirmed that both physically etched scars, and scars in color only, may be formed on bone; further demonstrating the causal link between the barnacles and scars were some barnacles that were damaged during preparation with a partial shell remaining in the ring-shaped scar, uncovered by removal of the partially damaged barnacle. 

Lastly, this study demonstrates that encrusting organisms can act as a taphonomic window into the post-mortem interval. Ordinarily, we wouldn’t have any idea of what happened during this period, but in the case of these barnacle encrustations, we know that the bones were reoriented (or not, in the case of the femur and scapula), and were encrusted for a minimum of 4-7 months. The potential for encrusting organisms to yield more information about the post-mortem interval is of course much higher for other potential conditions of preservation (e.g. a more complete specimen with numerous types of encrusting invertebrates). All this goes to show that much more work on the taphonomy of marine vertebrates is warranted, as much more information can be squeezed from the fossil record – and with regards to marine vertebrates, we have barely scratched the surface.

 References

BARNES, L. G., C. E. RAY, AND I. A. KORETSKY. 2006. A new Pliocene sea lion, Proterozetes ulysses (Mammalia: Otariidae) from Oregon, U.S.A., p. 57–77. In Z. Csiki (ed.), Mesozoic and Cenozoic Vertebrates and Paleoenvironments: Tributes to the Career of Prof. Dan Grigorescu, Bucharest, Romania.

BOESSENECKER, R.W. 2013. Taphonomic implications of barnacle encrusted sea lion bones from the Middle Pleistocene Port Orford Formation, Coastal Oregon. Journal of Paleontology 87:657-663.

DENNISON, K. J., J. A. KIESER, J. S. BUCKERIDGE, AND P. J. BISHOP. 2004. Post mortem cohabitation—shell growth as a measure of elapsed time: a case report. Forensic Science International, 139:249–254.

SANTOS, A., E. MAYORAL, AND F. MUNIZ. 2005. Bioerosion scars of acorn barnacles from the southwestern Iberian Peninsula, upper Neogene. Rivista Italiana di Paleontologia e Stratigrafia, 111:181–189.

Reflections on the 2013 Society of Vertebrate Paleontology Conference in Los Angeles, California

I’ve been back in New Zealand now for a week since my month-long trip to the US ended. The primary purpose of the trip was to present some of my dissertation research at the SVP conference (Society of Vertebrate Paleontology) in Los Angeles. This was my ninth (!) meeting, and my seventh time presenting research.

The day before the conference, I drove down from San Francisco with my labmate Cheng-Hsiu Tsai, who had been staying with me at my parents’ house. It’s about a 5 hour drive to downtown LA, and with stopping time included, we did it in about 6 – and got stuck in traffic on the 110 freeway shortly after turning off I-5; fortunately we only had to go for a couple miles to get to the Westin Bonaventure. Several years ago I decided never to stay outside the host hotel, unless there was a cheaper hotel literally next door – a situation I took advantage of at the 2010 Pittsburg meeting. The Westin Bonaventure hotel is pretty huge, and one of my first impressions upon entering was a number of movie and TV show posters – apparently several movies including Rain Man, Heat, and True Lies were filmed there – including the huge shoot out following the bank heist in Heat (where the Val Kilmer and Dennis Haysbert characters get shot). The conference hotel was great, although because of the circular shape and symmetry of the lobby, it had a pretty confusing and difficult to learn layout.

The first few days of the conference, as normal, didn’t have a whole lot of talks I wanted to see, so I spent quite a bit of time networking with colleagues, meeting with coauthors and potential future collaborators, and catching up with old friends. Notable non-marine mammal talks and posters included a great talk by Jim Parham (CSU Fullerton/Cooper Center) on fossil leatherback sea turtles (Dermochelyidae) and a related poster by Katrina Awalt. Dan Ksepka gave a talk on new sea birds from the late Oligocene of South Carolina, including a gigantic new pelagornithid (bony toothed bird). Dan even came up to me and jokingly apologized in advance; currently, the largest known flying bird from North America is the Pelagornis sp. specimen I reported on with N. Adam Smith in JVP in 2011, and this South Carolina specimen is slightly larger, and will unseat my specimen from the record. N. Adam Smith and a student of Dan’s had posters on osteohistology of modern and fossil flightless birds including penguins and the extinct flightless auk Mancalla (a subject I am increasingly more interested in for studying fossil marine mammals). Gabe Santos (Cooper Center) had a great poster on the taphonomy of the Eocene Talega Bonebed, a terrestrial mammal accumulation that is slowly being prepared by folks at the Cooper Center. Former Otago student (now at Ashoro Museum of Paleontology in Hokkaido, Japan) Tatsuro Ando presented a fascinating poster on the phylogenetic relationships of the extinct flightless plotopterid birds, and whether or not they were closely related to penguins as was recently proposed by Gerald Mayr.

 

Okay, this is out of order, but all of the photos I'm in were from the last night of the meeting. As usual, numerous Montana State kids are up in the front of the annual party photo... I promise, we actually do get some science done during this meeting! Photo courtesy Rebecca Hunt-Foster.

The first morning of the conference had a symposium on dinosaur ontogeny, organized and moderated by my good buddies at MSU Denver Fowler and John Scannella. Ontogeny is a subject that the paleontologists and numerous students at my alma mater Montana State University and Museum of the Rockies are fanatics about – as well they should – ontogenetic variation in skeletal morphology is seriously underappreciated in vertebrate paleontology. The poor understanding, and perhaps widespread ignorance of ontogeny has resulted in an over-proliferation of genera and species in dinosaur paleontology (for example, Triceratops-Torosaurus synonymy, and Dracorex-Stygimoloch-Pachycephalosaurus synonymy). It’s unclear how much this affects my own field; mammalian paleontologists have generally had less of a problem embracing ontogenetic changes, and with good reason: mammals only get a single set of adult teeth, and are relatively easy to group individuals of different ontogenetic stages together into concrete morphotypes. Cetaceans, on the other hand, attain immense sizes and their skulls change shape quite a bit; cetaceans either lack teeth altogether or have teeth that are so simplified as to be nearly completely useless for purposes of identification. So, there are perhaps a few parallels with dinosaur paleontology as far as ontogeny being problematic, and has almost certainly resulted in too many cetacean genera and species. To wrap this up, I was pretty interested in seeing some of these talks in order for some good perspectives on ontogeny, and also because many of the speakers were close friends (Denver Fowler, Cary Woodruff, John Scannella, Holly Woodward, and Sara Werning) or former professors of mine (Jack Horner, and David Varricchio – who ended up not being able to attend the meeting), in addition to UCMP curator Mark Goodwin. We heard some fascinating stuff about heterochrony in the Triceratops lineage, vertebral ontogeny in sauropods, pachycephalosaur ontogeny, growth and maturation in Maiasaura, and ontogenetic implications for the K/Pg extinction.

On the third night of the conference, Ewan nominated me (again) to round up people for the annual marine mammal paleo dinner. We ended up with about 30 people, and had a great time at California Pizza Kitchen; I got my check early and hoofed it back to the host hotel before the silent auction finished up. My prints didn’t make quite as much as I had hoped, but we’ll see what happens next year. After, I spent a few hours at the bar, and at 1am I realized I had only practiced my talk once before – at UCMP – where Kevin Padian, Pat Holroyd, and various students (including visiting Harvard student Anjan Bullar) gave me some great ideas for how to shorten the powerpoint. So, I grabbed a couple friends – my very close friends Alida Bailleul (MOR) and Jade Simon (MSU), and my buddy and coauthor Joe El Adli (formerly SDNHM, now U. Michigan) – and gave my talk at 1am out on the pool deck behind the bar. And I nailed it! It went great. I practiced it again the next morning to John and Kari Scannella; John is normally pretty critical (and constructive at that), but didn’t really have much to ask.

The marine mammal session had a number of great talks. Erich Fitzgerald gave a talk reevaluating some scrappy phocid remains from the Beaumaris locality in Australia as well as a phocid braincase from New Zealand. Former San Diego State student (Berta lab) Sarah Kienle gave a talk on feeding ecology in pinnipeds, and Morgan Churchill gave a pretty interesting talk on tooth spacing in pinnipeds and whether or not Enaliarctos (the dawn seal) was truly a pierce feeder. Mark Clementz gave a talk on sirenian isotopes, and Daryl Domning gave an interesting presentation on the Metaxytherium sea cow lineage. Cetacean presentations included talks by my labmate Cheng Hsiu Tsai on mysticete phylogeny, a presentation by Ewan on tusked dolphins from the Oligocene of New Zealand, a talk by Olivier Lambert on squalodontids from Peru, and a last minute presentation by Rachel Racicot on odontocete inner ears. Phil Gingerich also spoke about sirenian and cetacean faunas from the Fayum. I also gave my own presentation which went over pretty well, on some of my dissertation research focusing on a new eomysticetid taxon represented by an adult and juveniles of different sizes, preserving the first known ontogenetic series for an archaic mysticete.

Jack and I after the banquet. Jack has tolerated six or seven years of my weird 

marine mammal shenanigans. Photo courtesy Alessandro Carpana.

Although the marine mammal session is always the highlight of the meeting for me, there was one special event left. At the awards banquet, my former professor Jack Horner was given the Romer-Simpson Medal, the highest award given by SVP. Jack gave a great little talk with a short biography (with all sorts of great old photos from the 60’s and 70’s I’ve only seen once or twice before), and actually spent most of it talking about how proud he was of his various students. I took several courses from Jack, and spent an inordinate amount of time over at Museum of the Rockies using the preparation laboratory; Jack gave me permission back in 2005 to start lugging in fossil marine mammals in ridiculously hard concretions, as MOR had the only pneumatic air tools I could have access to. My undergrad adviser, David Varricchio, was Jack’s first graduate student, and owing to Jack’s teaching – and all the time spent talking about paleontological theory with his students (or just getting “merry”) – Denver Fowler, Liz Freedman, John Scannella, Holly Woodward, Laura Wilson, Cary Woodruff, Alida Bailleul, and others – I’m very much in a similar frame of mind and have had the fortune to apply my unique MSU/MOR perspective on vertebrate paleontology to fossil marine mammals. Because of this academic heritage, I was pretty damn proud to be a part of the (rather enormous) group photo of Jack and Mark Goodwin with all of his students on the stage after the banquet. Up there with me were pretty much all of my best friends from Montana, and I am so damn proud to have graduated from that unique group of stellar thinkers.

 

The Montana State University-Museum of the Rockies-UCMP group. Photo courtesy Alessandro Carpana and Anna Giamborino.

To wrap it up, I guess I’d say that this meeting was one of the more productive, and definitely the most fun I’ve ever had at SVP. Knowing that I probably will not have a chance to go to the 2014 meeting in Berlin (and even if I did, many close friends will not), I knew this would be my last chance to see quite a few old friends from my Montana days, and I made a point of putting a stop to “talking shop” after the poster sessions ended, and spending the evenings with old friends. It was a great time, and I feel extremely fortunate to have been able to see any of them, even if for only four days. As I write this, my wife is currently in Billings, Montana, and tomorrow will be heading to Bozeman – the first time either of us have been back since 2011 – to see some of our old friends (and I am extremely jealous!). On a parting note, it's not easy living so far away from literally everyone you've ever known or cared about - and I generally have made a good attempt at putting on a game face. I didn't realize how much I missed everybody until the conference was over - and certain friends got a rare (if not embarassing) peek behind the armor. It all goes to show that I really have to get this dissertation finished, so Sarah and I can return to the US and make a bunch of visits to current and former MSU students spread across the four corners of North America!

Reconstructing the skull of Neophoca palatina: a fossil relative of the Australian sea lion from the Pleistocene of New Zealand

When Morgan Churchill visited Dunedin for his EAPSI fellowship in July and August, we secured a loan of the holotype skull of Neophoca palatina for study and repair. Judith King published her study of the specimen and named it in 1983, and returned it to New Zealand by mail; unfortunately, it was damaged in transit. Part of this is likely due to uneven acid preparation of the specimen; a thin, horizontal zone of calcareous sediment was totally dissolved away, including through the turbinates - leaving the palate and braincase connected only by thin, vertical sheets of the maxilla - which fragmented into many small pieces.

Our first stab at putting humpty dumpty back together. The brown skull is a cast of the type specimen, with a modern Phocarctos skull for comparison.

After Morgan returned from Australia and the North Island, he hand carried the type skull back to Dunedin. At this stage, the holotype consisted of a fragmentary palate and a mostly complete braincase, and many fragments of the dorsal part of the rostrum and posterior palate.

The holotype braincase of Neophoca palatina (bottom), a cast of the holotype (left), and an Arctocephalus skull (right).

The remains of the Neophoca palatina holotype; the palatal fragment is dorsal up, and the braincase is ventral up.

Some matches already! Here's the palate in ventral view.

Within minutes of opening up all of the bags and unwrapping the fragments, we started to see some obvious joins - and started gluing right away. Within the first few days of Morgan returning, we had the majority of the bone fragments glued back in place.

Morgan sorts through skull fragments in the paleo lab.

Morgan sorting through more fragments...

So there were lots and lots of fragments...

All the king's horses and all the king's men couldn't put [Neophoca palatina] back together again.

At present, the majority of pieces have been glued back together, but remain in separate sections; Ewan suggested that we not proceed with gluing the final pieces back on until we get some good photographs of the skull pieces prior to reassembly, so that we can document the dorsal surface of the palate, and ventral surface of the broken intertemporal region - which will not be accessible once the skull is reassembled. Granted, prior to breakage, these surfaces were not visible - but, since we have the opportunity to document morphology that would otherwise be inaccessible - it is best to carefully document what we can. Similarly, recently the rostrum of the type cranium of the dolphin Waipatia was broken - so Ewan took the opportunity to photograph the broken cross section prior to gluing it back on. In another specimen - one of my eomysticetid specimens I'm studying for my dissertation - the mandible is fragmented into four pieces, and I'd like to photograph each broken surface before I reassemble it.

Trends in publishing for west coast Cenozoic marine vertebrate paleontology, 1960-2013

On a coffee-fueled whim I decided to type up a spreadsheet of publications relating to west coast marine vertebrate fossils in order to take a look at the number of publications per year. I decided to limit this first iteration of the spreadsheet to studies published in 1960 and later. Why have I done this? I'm curious as the number of researchers in marine mammal paleontology in general - and more specifically researchers focusing on west coast Cenozoic marine vertebrates (birds, bony fish, sharks, sea turtles, and marine mammals) - seems to be higher than ever. Make no mistake - I'm not lamenting it as a problem; I don't foresee marine mammal paleontology ever having the problem dinosaur paleo has at the moment with an extreme surplus of young researchers, driving competition for specimens, overselling of crappy fossils, disputes over generally miserable material, or re-reinvention of the wheel (I've seen some papers redescribing a crappy dinosaur that was redescribed only a decade ago). In marine mammal paleontology, we have an enormous surplus of beautiful fossils - quite the opposite problem. The apparent abundance of other researchers at the moment - and increasing numbers of young researchers in my field - means more options for collaboration, and a larger pool of peer reviewers than ever before. I can only see it as a positive.

West coast marine vertebrate paleontology has never been a large field. While it can be drawn back as early as O.C. Marsh and E.D. Cope describing things like Desmostylus and "Eschrichtius" (now Balaenoptera) davidsonii from the Neogene of California, it did not really kick off until the early 20th century with the numerous publications by D.S. Jordan on the fossil fish and sharks, and Remington Kellogg in the 1920's on fossil marine mammals from California. Beginning in the 30's and 40's, the study of fossil marine birds began in earnest with the studies of Alexander Wetmore, Loye Miller, and Hildegarde Howard (who continued to publish well into the late 1980's). After the 1930's, marine mammal work sagged as Kellogg focused on the enormous cetacean fossil collections from the Chesapeake bay region - which he would continue until his death in the late 1960's. In the early 1960's, Ed Mitchell began work on fossil pinnipeds, and was followed a decade later by the recently retired curator of Paleontology Larry Barnes. Most of Barnes' early work focused on fossil pinnipeds and odontocetes from southern California and Oregon. Charles Repenning began work in the late 1960's on fossil pinnipeds from Isla Cedros, which he eventually published in what is arguably my favorite paper (Repenning and Tedford, 1977). In the 1970's, Daryl Domning began a career of studying fossil sirenians; his 1978 monograph on sirenians from the eastern North Pacific is pretty inspired in my opinion. The 1970's also saw numerous studies on fossil sharks published by UC Berkeley Ph.D. student Bruce Welton. Research by Barnes, Domning, and Welton was supplemented in the 1980's and early 1990's by the next generation of paleontologists including Tom Demere, Annalisa Berta, Douglas Long, Bob Chandler, Kenneth Warheit. In recent years, another generation cropped up including Brian Beatty, Nick Pyenson, Meredith Rivin, Jim Parham, Tom Stidham, N. Adam Smith, Eric Ekdale - and an even more recent group including Jorge Velez-Juarbe, Rachel Racicot, Morgan Churchill, Joe El Adli, and myself (I've probably forgotten names, please yell at me to add some if you think of them).

When I started looking into fossil marine mammals and other vertebrates from California, I was surprised with how much remained unpublished. I've sort of been fascinated with the subject for several years. The impression I had was that there was quite a lot of research published in the 1970's through early 1990's, with a big lull in research during the late 1990's. At the moment, it seems that there is more interest in the subject than ever, and I think we might be on the cusp of a renaissance in west coast marine vertebrate paleontology. And we can sort of test this nebulous hypothesis with this fancy spreadsheet I put together.

Criteria

In order to qualify, I made a short list of requirements: 1) studies must be published articles or book chapters; I'm not interested in tallying up meeting abstracts, as it would be a big pain and isn't really a measure of productivity (which I suppose is more of the focus rather than strictly 'interest' in the subject). Studies must also 2) focus on marine vertebrates from 3) Cenozoic rocks from 4) Baja California, California, Oregon, and Washington (eventually I will add in papers on marine vertebrates from British Columbia and Alaska). I'm not really interested in looking at papers detailing fossils from older marine rocks, simply because it's outside of my research interest (and therefore memory), but Mesozoic vertebrates are generally worked on by a separate coherent 'block' of researchers. What sorts of studies don't count? Papers on terrestrial mammals preserved in otherwise marine formations, and papers on bony fish from fluvial deposits, for example.

Ok, that's great, but how much does a paper have to focus on marine vertebrates from that region in order to be included? That's a bit fuzzier. There is clearly a wide spectrum of relevance, from alpha taxonomic papers describing new fossils from this region, to papers that merely include a west coast marine vertebrate fossil in a cladistic analysis. I decided to not include the latter, as some fossil marine mammals - e.g. Enaliarctos, Albireo, Parapontoporia, Parabalaenoptera - are included in numerous cladistic analyses from studies published on fossils from other regions, and merely including one of those in an analysis isn't really a contribution to west coast marine vertebrate paleontology, in a sense. So, at the bare minimum, a study has to include at least some passage of text focusing on west coast fossils, or include a figure of one. Admittedly, there are far fewer of these 'fuzzy' in between examples than clear cut alpha taxonomic studies (e.g. Repenning and Tedford 1977, Otarioid seals of the Neogene).

Format

I've kept it pretty simple so far: I just have four columns, including subject, author, year, and title. I haven't including any more bibliographic information at this point, and unless I actually publish this, I'm not going to waste my time doing that. Subjects include: Aquatic Carnivora (pinnipeds, otters, and Kolponomos), Odontoceti, Mysticeti, Sirenia, Osteichthyes, Elasmobranchii (which should actually be Chondrichthyes because I have at least one study on chimaeras in there), Aves, Assemblages (for papers reporting on more than one group), and Taphonomy (for studies that focus mostly on fossil preservation and may include more than one group). So far I've not implemented a way to have secondary subjects for assemblage and tapho papers to count for each taxonomic subject represented.


Results

Using pivot tables in Excel I have generated histograms from the spreadsheet, each of which is shown below. I apologize for the crappy Excel graphics; this isn't a publication, so I'm not going to spend a bunch of time making pretty graphics in Illustrator. NOTE: Keep in mind that since this is a quick n' dirty in excel, years that have zero publications are not included on the X-axis, and thus each graph makes publishing look more constant at first glance.

ALL MARINE VERTEBRATES

At the largest scale with everything thrown on the board, a couple trends are apparent: there is quite a bit of noise from year to year, and the maximum possible number of publications has increased in the last two decades. The former may simply reflect the "reset" time between publishing articles; not every researcher gets a paper published every year (or, may have published articles that did not meet the criteria for inclusion). Many prolific researchers have diversified since their early work into studying fossils from the east coast or even Japan.

We have some serious spikes here: what the heck happened in 1994-1995? Also, 2008 and 2013 were/are crazy (and there's still three months left in 2013!). Firstly, 1994 and 1995 saw publication of two special volumes: the Frank Whitmore volume in 1994 and the Island Arc special volume on marine vertebrates in 1995 (fun fact: although articles from the Island Arc issue say 1994, they were actually published in January 1995 and need to be cited as such; same goes for the 1976 Systematic Zoology special volume, which says 1976, but in reality was published January 1977). 2008 and 2013 do indeed have record numbers of publications - but unlike the mid 90's spike, it is unrelated to special volumes.

What else is evident is that there is indeed a slump in the late 1990's; I have no idea what to attribute this to, but it is refreshing that my impression was correct. However, publishing prior to the 1990's doesn't appear to have ever been very high, so that was an incorrect impression on my part.

 ALL MARINE MAMMALS

Looking specifically at marine mammals, some of the trends are similar to before; however, a spike in 1977 is more obvious here, relating to the publication of the 1977 Systematic Zoology special volume. There's also a pretty solid spike from 1984-1986. The post-Island Arc volume lull is even more obvious here; keep in mind that 1999 and 2000 had zero publications, so they're not even included on here.

I'm still not sure what happened in 2008. The lower peak for 2013 is because of several papers on birds and sharks published this year (which would not show up on this histogram).

AQUATIC CARNIVORES

Holy walruses batman, 1994 was a good year for pinniped research. 1994 saw publication of two papers by Tom Demere on walruses, the Berta and Wyss phylogeny, the paper on pinniped basicrania by Hunt and Barnes, the paper on Kolponoms by Tedford et al., and two others that are escaping my memory as I type this (I don't have the spreadsheet in front of me at the moment).

CETACEANS

So now we see that much of the 2008 and 2013 spikes are due to paleocetological studies.

 NON MAMMALS (bony fish, sharks, turtles, birds)

I lumped all of these into one chart because this combined group is approximately similar to paleo marine mammalogy. Here you can really appreciate a post-1970's sag in research, with much of the 1970's and 1960's dominated by research on birds by Hildegarde Howard, shark work by Bruce Welton, and bony fish work by John Fitch. After Howard passed away, only a couple of papers were published on west coast marine birds until the last few years. Similarly, shark and fish work has picked up by work from Gary Takeuchi (LACM) and colleagues, and the "retirement" of Bruce Welton from the petroleum industry (and "un-retirement" from paleoichthyology; he's published two papers on fossil basking sharks this year, and from what I hear there are several more on west coast sharks in the works).

So, new impressions from this data?

1) Although there is a general increase in the number of papers per year (or, more specifically, higher maximum possible number, with inter-year lags in research output), there was a very real lull in research in the late 1990's. The increase through time likely reflects continued research output by the older generations of researchers, supplemented by the addition of younger generations.

2) Non-mammal work was severely slowed down after the late 1980's, but has recently picked back up.

3) 2008 and 2013 tied for record-breaking numbers of papers (14 each), with 2009 and 2011 having impressive numbers as well (8 and 9, respectively). The 2008 spike is dominated by cetacean studies, whereas 2013 is a bit more even in terms of subjects.

Anyway, that's about all for now, but I am really interested to hear what other people have to say about this. One last point: I know for a fact that I have missed certain papers, and several have come to mind already as I type this (e.g. Barnes 1970, Allodesmus mandibles in PaleoBios). I will upload a copy of the spreadsheet, and if folks are interested they can scour it for mistakes or omitted papers.

New cast received by mail: Squalodelphis fabianii - "baseball cards" for scientists

I apologize for the month-long lapse in posting; I've been pretty busy pushing along on a number of fronts, particularly on my dissertation research. Lots of writing, preparation, photography, ammonium chloride coating, powerpoint presentation-making, and perhaps most notably - learning how to embed fossil bone fragments in epoxy for preparing paleohistology slides. I've still got a ton of stuff to do in the next 8 days - I have a week left until I fly home to California to see my family, visit a bunch of museums, and present on my dissertation research at the annual Society of Vertebrate Paleontology conference in Los Angeles. Nevertheless, I have decided - in favor of preserving my sanity - to take a break from all the serious stuff and spend some time blogging and thus returning to paleontological 'cheerleading'.

In vertebrate paleontology, it is imperative to directly examine fossils when conducting research. If a museum is too far away and too expensive to visit, then a good cast makes for an excellent alternative. Sometimes we will get the chance to examine important specimens in person - but if they are particularly important, for example - closely related to a fossil under study - then possessing a cast for comparison and longish term study is just as useful. For example, I've never had the opportunity to visit France or South Africa, but at the Smithsonian I was able to examine and photograph casts of the true seals Piscophoca and Homiphoca (in collections of said countries); similarly, I have not made plans (and will not have the budget) to visit collections in Japan, and in our department we have a cast of the Oligocene Japanese mysticete Aetiocetus polydentatus.

Recently, Yoshi has been making numerous casts of the Oligocene dolphin Waipatia maerewhenua, one of the most completely known Oligocene cetaceans - for trading with other institutions. So far, casts of Waipatia have gotten us casts of Piscobalaena from the MNHN, Aetiocetus polydentatus from the Ashoro Museum of Paleontology, and most recently - the early Miocene longirostrine odontocete Squalodelphis fabianii from Italy.

We also received a fresh copy of Giorgio Pilleri's enormous (if ponderous) and beautifully illustrated monograph on the Odontoceti of the early Miocene Belluno Sandstone of Italy.

 Labmate Yoshi Tanaka pulls out a bubble wrapped skull.

 Gorgeous! Yoshi and I ogling the the freshly unwrapped cast of the holotype of Squalodelphis fabianii.

It's like Christmas morning for a paleocetologist!

Spotted shags, fur seals, and yellow eyed penguins at Katiki Point

After leaving Moeraki Boulders, we went to the southern point of the small peninsula to Katiki Point. Katiki Point boasts a lighthouse, paua diving (paua is the Maori word for abalone), and viewing of fur seals, yellow eyed penguins, little blue penguins, spotted shags, stewart island shags, and other seabirds.

This adorable donation box greeted us at the parking lot.

This pretty much sums up New Zealand in a single photo.

A female NZ fur seal (Arctocephalus forsteri) hauled out on some rocks.

This NZ fur seal (Arctocephalus forsteri) woke up from a nap in the sun when we approached.

A single Stewart Island shag (Phalacrocorax chalconotus) flies across the water.

A trio of spotted shags (Strictocarbo punctatus) at Katiki Point.

At Katiki Point, there's an entire rookery of spotted shags (Strictocarbo punctatus) which can be easily approached and photographed.

 

Two spotted shags (Strictocarbo punctatus) being somewhat goofy.

Spotted shags (Strictocarbo punctatus) get their name from the numerous black spots on their wings. Between those (which you cannot really appreciate unless you get close), the white and black stripes on the neck and head, and the blue eye patch - these guys are easily the most beautiful cormorants.

More spotted shags (Strictocarbo punctatus).

Even more spotted shags (Strictocarbo punctatus).

Nic and I found this fur seal (Arctocephalus forsteri) pup carcass, which demonstrates fairly well a taphonomic observation of mine regarding the early loss of rostral elements in otariid pinnipeds. Unless a carcass is pretty fresh, the maxillae, nasals, and premaxillae are often lost - leaving just the braincase. I've got a manuscript in preparation on this topic at the moment.

Nic, Sarah, and Maria waiting in the penguin blind. We spotted 8 yellow eyed penguins in only an hour.

A subadult yellow eyed penguin (Megadyptes antipodes) has some trouble negotiating the surf. This poor guy got knocked around by waves about four times.

A single adult yellow eyed penguin (Megadyptes antipodes) just outside the blind.

Another yellow eyed penguin (Megadyptes antipodes) comes ashore in the afternoon. This individual had less distinctive head coloring, suggesting it was a bit younger.