Examining coevolution in Argentinean fossils
Here are two very recent publications describing some of our findings. In one paper, we present a new chronology for Gran Barranca using U/Pb radio isotopic dating techniques, and in the second paper we describe the ancient vegetation of Gran Barranca from phytoliths. One of our major findings is that "grazer" tooth forms seem to have evolved in Patagonia in the absence of grasslands. This idea overturns assumptions that many paleontologists have made for years about South American vegetation during this time period. Instead, it appears that grasslands are much more recent than previously presumed, in fact, we are still on the hunt for them. We are exploring other geographic areas and younger rock outcrops to answer this question. Stay tuned...
Strömberg CAE, Dunn RE, Madden RH, Kohn MJ, Carlini AA. (2013) Decoupling the spread of grasslands from the evolution of grazer-type herbivores in South America. Nature Communications 4:1478. doi:10.1038/ncomms2508 (UW Today article)
Dunn RE, Madden RH, Kohn MJ, Schmitz MD, Strömberg CAE, Carlini4 AA, Ré GH, Crowley J. (2013) A new chronology for middle Eocene–early Miocene South American Land Mammal Ages. GSA Bulletin 125(3-4):539-555.
-- Regan Dunn