The large Pleistocene cat Homotherium serum, from Texas (in the Texas Memorial Museum.)
There were several interesting mammal talks today. Two of these involved fossil land mammals that were found in sedimentary rocks that were formed in the ocean. Kevin Seymour of the Royal Ontario Museumspoke on a cat skeleton from the Pliocene-age San Diego Formation in California. This is the most complete Pliocene cat skeleton ever found in North America, and may be close to the common ancestor of the lynx, ocelot, and puma. This was followed by Zhijie Zseng of UCLA, along Xiaoming Wang and J. D. Stewart of the Los Angeles County Museum, reported a mustelid (the family that includes otters, wolverines, and weasels) that was found in the Miocene Temblor Formation, and has teeth modified for eating hard materials like bone.
Julie Meachen-Samuels and Blaire Van Valkenburgh, also of UCLA, noting that large cats mostly eat prey larger than themselves while small cats tend to eat smaller prey, analyzed the skull and limb proportions of various cats to see if the different feeding styles were reflected in the bone shape. They found a good relationship between bone shape and feeding style (for example, cats that eat large prey tend to have shorter, wider mouths.) The only unusual point was that the big sabre-toothed cats had unexpectedly strong front legs, comparable to living cats that hunt in trees. Meachen-Samuels and Van Valkenburgh suggested that, compared to modern large cats, the sabre-toothed cats were more capable of wrestling their prey to the ground with their front legs.
In the last talk of the afternoon, Paul Koch of UC-Santa Cruz and several colleagues presented data on elephant seal and penguin distributions in Antarctica over the last few thousand years. Their data show that Antarctica has gone through several cooling and warming trends over the last 10,000 years. During the warm periods the Ross Sea is ice-free for part of the year, allowing elephant seals to breed along the coast there. The Ross Sea was warm from 2300 years ago until around 500 years ago, when it started cooling again (that cooling has been interrupted in the last 100 years by the new warming trend.)
During the afternoon poster session there were several posters on the sediments found in and around Badlands National Park including one by Emmett Evanoff of the University of Northern Colorado on the Oligocene Brule Formation, and another by Heidi Minkler of the South Dakota School of Mines on the Eocene Chadron Formation.
A poster of particular interest to me was one by Ralph Eshelman, Brian Beatty of the New York College of Osteopathic Medicine, and Darryl Domning of Howard University, on land mammals from the Miocene deposits along the Chesapeake Bay–the same deposits I work on (see my earlier post on Carmel Church land mammals.)