Sunday, October 13, 2013

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.

Sunday, October 6, 2013

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.


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).


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.


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.


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.


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).


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).


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!