01 May 2014

Conference Review: North Central GSA

Smilodon Mosaic in the Nebraska State Capitol
Ask a random person on the street what state they most closely associate with fossils and, after having stared at you you just long enough to determine just what kind of lunatic you are for asking such a bizarre question, they will probably respond with one of the Northern Rockies states (I'd bet that the most common response would be Montana, though I have no actual data to back this up).  However, a case could be made that they all should be answering Nebraska, which is probably the best place on Earth to find Cenozoic mammal fossils (it's also very good for Cretaceous marine fossils, if that's the sort of thing that floats your boat).  This is best illustrated by proboscideans, which have been found in 91 of the state's 93 counties, but mammals of all kinds have been found throughout the state.  The University of Nebraska has had an active paleontology program since E.H. Barbour's arrival in 1891, and the quality of the collections and research at the university have made Lincoln a paleontological mecca ever since.  Needless to say, then, when the Geological Society of America holds a regional meeting in town, paleontology is going to headline the program.  I attended the North-Central GSA in Lincoln last week, and here are some of my thoughts on the paleontology currently being conducted in the middle part of the continent (the abstracts and presentations can be viewed here if you want more detailed information on any of the talks):

  • Nebraska professor Jason Head spoke about a subject very near and dear to my heart: how the fossil record can inform models of future ecological change.  Ecological niche models take the climatic conditions in which an organism lives today and use these to predict where the range of that animal might shift as climate warms in the future.  However, many studies have shown that these models generally fail (sometimes spectacularly) to predict ranges of species during periods of past climate change.  Jason Head's study was interesting because he used fossil occurrence data and paleoclimatic reconstructions for boid snakes to augment ecological niche models, and found that the models that included paleoecological data predicted somewhat wider ranges for rubber and rosy boas in the future than did models based purely on modern data.
  • Did you know sloths have an especially high rate of dental anomalies (i.e., they frequently have either fewer or extra teeth)?  I didn't until I saw Robert McAfee's talk last week.  What's more, not only do living tree sloths often have abnormal numbers of teeth, but so did extinct ground sloths.  In fact, McAfee suggested that rates of caniniform tooth loss in Paramylodon from Rancho La Brea were so high that the population may represent the beginning of a speciation event that was nipped in the bud by the Pleistocene megafaunal extinction.
  • Joseph Peterson spoke about dinosaur paleopathology, and in particular on the use of 3D reconstructions of a hadrosaur vertebra with tooth marks on it (as well as theropod jaws) to determine the identity of the animal that bit the vertebra.  Turns out it was most likely a juvenile Tyrannosaurus.
  • My old officemate Jonathan Calede spoke about his dissertation work in the Cabbage Patch Beds of Montana.  The Cabbage Patch Fauna (named after a bar, not the creepy dolls, to paraphrase Jonathan) has been uncovered from several sites, which Jonathan found to be broadly similar in terms of geology and quality of preservation, suggesting that any trends observed between these sites represent genuine ecological patterns rather than taphonomic bias.
  • Nebraska's Shane Tucker discussed one of the coolest fossil sites of which I've ever heard: the Happy Jack Mine in the central part of the state.  The tunnels of the mine intersect infilled rodent burrows from the Miocene, allowing the 3D structures of these burrows to be observed.  On balance, the burrows most closely match those of ground squirrels, though gophers may have been responsible for some.  Shane and George Corner also presented talks about Miocene faunas from elsewhere in the state, underscoring the absurd richness of the Nebraska fossil record.
  • Ross Secord and his student Tom Baldvins both spoke about isotopic records across two important intervals of climate change: the Paleocene-Eocene Thermal Maximum and the glacial-interglacial cycles of the Pleistocene, respectively.  I was particularly interested in Baldvins' talk, which showed that C4 grasses were more abundant in the northern Great Plains during interglacial periods.  More intriguingly (to me, at least) his analysis of horse body size from the same sites showed a positive correlation with temperature (i.e., horses were larger in warmer climates).  Always nice to see another study that shoots holes in Bergmann's Rule, though I'd be curious to see if the trend would persist with a larger sample size and using tooth-based estimates of body size.
  • An entire session was devoted to the White River Group and its fossils, which was not only interesting in and of itself, but gave some great ideas for the design of the Sedimentology & Stratigraphy class I'll be teaching next year.  Particularly intriguing to me was Kurt Spearing's talk on the first evidence of inner ear bones in nimravids.  Ear morphology is hugely important in carnivore phylogeny, and I have high hopes that more nimravid ear ossicles will turn up in the coming years, which could potentially help determine where in the feliform tree these enigmatic animals belong.
  • I also spoke at the conference (on the humerus morphology of felids and whether or not it can be used to identify the huge cat that was present in the Late Miocene of western North America), but perhaps more importantly, for the first time I had a student presenting.  Laurel Perper discussed some of the early findings of our project comparing the morphology of the bizarre South American marsupial sabertooth Thylacosmilus, the subject of this month's upcoming Fossil Vertebrate of the Month feature.
Carnivore reconstructions by Mark Marcuson
I would be remiss if I finished this post without mentioning that, as expected, the University of Nebraska was an excellent host.  Besides pulling off a very well-run conference, Lincoln remains an excellent place to spend a few days (if nothing else, it's one of the only places in the northern Plains where you can reliably find good food and drink after 8:00).  As I always do when I'm in town, I spent some time in the University of Nebraska State Museum, home of, among many other things, the largest collection of fossil proboscideans in the world.  They were also featuring an exhibit on the paleoart of Mark Marcuson, whose murals I'd seen in the museum before but with whom I had been largely unfamiliar.  Another paleoartistic effort of which I'd previously been ignorant but that I visited this time on the suggestion of Nick Famoso is the mosaic on the floor of the Nebraska State Capitol (see picture above), which depicts reconstructions of fossils animals from trilobites to mammoths.  Any state that puts prehistoric life front and center in the rotunda of its capitol is a good one in my book, and as far as I'm concerned cements Nebraska's status of most fossily of fossiliferous states.

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