I managed to make it to a few more talks today, including several elephant talks.
There are two generally recognized species of mammoths in North America, the cold climate woolly mammoth Mammuthus primigenius and the warm climate Columbian mammoth M. columbi (above, from the Page Natural History Museum). Ross MacPhee and others examined mitochondrial DNA from these two species and found evidence that there was at least some cross breeding between these two species.
Kirk Johnson and others reported on the recently discovered Snowmass site in Colorado. This high high-altitude location includes sediments deposited in a glacial moraine-bounded lake, and includes bones from nearly 60 taxa, mostly mammals and amphibians. In an impressive salvage operation, the Snowmass team recovered several thousand bones in just 2 months.
Xiaoming Wang and others reported on a Pliocene mammal fauna from Tibet, that includes early examples of the woolly rhinoceros Coelodonta. While it has often been assumed that cold-adapted Pleistocene mammals evolved in response to the onset of the Ice Age, they suggest that many of these animals may have already evolved their cold-weather adaptations in Tibet in the Pliocene or earlier, with the Ice Age simply allowing them to move off the Tibetian Plateau and disperse into other areas.
Ryan Carney and others reexamined the original Archaeopteryx feather (that was recently demoted from its status as the type Archaeopteryx). Using an SEM, they determined that the feather was likely an upper primary feather, and its microstructure shows that it was most likely originally black in color. (Closeup of the wing on the Wyoming Dinosaur Center Archaeopteryx.)
Garath Dyke, Mátyás Vremir, Gary Kaiser, and Darren Naish reported a small deposit from Romania that is made almost entirely of eggshell fragments (with a few complete eggs) and bones from baby enanornithine birds. They interpret this as a nesting colony that was destroyed in a flood.
In the poster session, Vince Schneider, Andy Heckert, and Nick Fraser reported an aetosaur from the Triassic Pekin Formation in North Carolina. The unusual osteoderms (bony armor) pattern in this specimen suggests that it may represent a third Pekin Formation aetosaur species (Longosuchus, below from the Texas Memorial Museum, may be related to the North Carolina specimen.)
Ignacio Cerda and others reported the first sauropod dinosaur from Antarctica, a single incomplete caudal (tail) vertebra from a titanosaur (titanosaur model below from the Museo de Historia Natural de San Marcos).
Jay O’Sullivan examined the Miocene horse Archaeohippus blackbergi to look for evidence of sexual dimorphism (example below from the Florida Museum of Natural History, about to be eaten by Amphicyon). He suggests that the high mortality rate of young adults may be due to male-male combat, and that the enlarged canines and heavily-built lower jaws in the males suggest that they were biting each other.
Tina Campbell, George Bromm, and Richard Hilton reported an amphicyonid skeleton from the Miocene of Nevada that suffered from advanced osteoarthritis. This is an unusual condition for amphicyonids, as it would seem they would have difficulty catching prey with such a condition. (The amphicyonid below is on exhibit at the American Museum of Natural History.)
Virginia Naples compared the jaw mechanics of the cat Xenosmilus hodsonae (below, from the Florida Museum of Natural History) to other sabertooth cats, such as Smilodon. The jaw mechanics in Xenosmilodon are quite different, suggesting different biting style than in other, superficially similar cats.
After the posters we rushed over to the Shark Reef Aquarium at Mandalay Bay for a guided tour. We spent two pleasant and informative hours at the aquarium, and I’d like to thank the staff there for making our visit so enjoyable.
More tomorrow, including my poster.