|Smilodon Mosaic in the Nebraska State Capitol|
- 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|