SVP 2012 meeting, Day 4

Today was the last day of the SVP meeting. I started off the morning with a series of talks on mammal feeding. Brian Beatty and Matt Mihlbachler continued their examination of techniques for examining microwear on mammal teeth, reiterating that the observer is a significant variable in these studies, and that many things other than diet can affect microwear.

Gina Semprebon et al. examined microwear in horses from the Eocene to the Pleistocene, finding that the amount of abrasion has increased over time. This mirrors previously published mesowear studies.

Larisa DeSantis et al. reported yet another microwear study, but this time in the Pleistocene cats Smilodon fatalis (sabertoothed cat, top) and Panthera atrox (American lion, below). Suprisingly, they found that the giant P. atrox showed microwear more similar to a cheetah than to a lion, suggesting that it rarely ate bone.

In another Smilodon talk, Julie Meachen and Robin O’Keefe showed that the shape of Smilodon lower jaws from Rancho La Brea change over time, possibly partially in response to climate changes.

Stephen Wroe et al. used examined bite forces in Smilodon and the sabertooth marsupial Thylacosmilus atrox (below), finding that Thylacosmilus had a remarkably weak bite. They suggest that the two species used rather different killing techniques, with Thylacosmilus stabbing rather than biting its prey.

Continuing with marsupials, Borja Figueirido, Christine Janis, and Dominic Wu examined the forelimbs of the recently extinct Tasmanian wolf Thylacinus cynocephalus (below), finding that it was not likely to be a pursuit predator like a true wolf.

I also hit a few reptile talks in the morning session. Adam Pritchard et al. reported a new drepanosaurid from the Triassic of New Mexico and reviewed the group’s weird forelimb morphology. How weird? In some drepanosaurs the claw on the second finger is actually considerably larger than the radius; imagine if your fingernail was longer than your forearm! Drepanosaurs also have highly modified ulnae, metacarpals, and carpals.

Nick Fraser et al. reported a new small protorosaur from China, the same group that includes Tanystropheus and Tanytrachelos (below). The new species has a mix of characters that make it difficult to determine its relationships.

In the afternoon session Lindsey Yann and Larisa DeSantis reported measurable differences in stable carbon and oxygen isotopes in mammals from different Plesitocene sites in Florida, apparently reflecting climate variations in the Pleistocene.

Anna Behrensmeyer has been studying the taphonomy of modern skeletons in Amboseli National Park, Kenya for over 30 years. A 2009 drought at her and her colleagues to examine how a mass mortality event changes the skeletal record of the area. While the species breakdown was not greatly affected, mass kill tended to produce more complete skeletons, at least in the short term.

Bobby Boessenecker (author of The Coastal Paleontologist) and James Schmitt examined characteristics of marine bonebeds in the Miocene-Pliocene Purisima Formation of California, describing in some detail variations in bone preservation caused by differences in sediment transport and sedimentation rate; obviously this has some bearing on my Carmel Church work. One thing that struck me is that bite marks are very rare on bones in the Purisima, while they are exceedingly common at Carmel Church.

I was only able to spend a short time at the posters. Mark Uhen reported some new protocetid whale remains from New Jersey, and Yoshihiro Tanaka and Ewan Fordyce examined characters which can be used to define the Platanistoidea, the toothed whale group that includes the squalodonts.

I was unable to spend more time in the posters because I had to return to Martinsville to get some museum vans. In the morning I’m leading a post-meeting field trip to Carmel Church.

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