THE EVOLUTION OF GIANT MAMMALS: TRAJECTORY AND CONSTRAINTS on BODY SIZE OVER THE CENOZOIC

SMITH, Felisa, Department of Biology, University of New Mexico, MSC 03-2020, 1 University of New Mexico, Albuquerque, NM 87131, BOYER, Alison G., Department of Ecology and Evolutionary Biology, Yale University, Box 208106, New Haven, CT 06520, BROWN, James H., Biology, University of New Mexico, MSC 03-2020, 1 University of New Mexico, Albuquerque, NM 87131, COSTA, Daniel P., Department of Ecology and Evolutionary Biology, UCSC, Santa Cruz, CA 95064, ERNEST, S.K. Morgan, Department of Biology and Ecology Center, Utah State University, Logan, UT 84322, EVANS, Alistair R., School of Biological Sciences, Monash University, Victoria, 3800, Australia, FORTELIUS, Mikael, Department of Geosciences and Geography, Institute of Biotechnology, University of Helsinki, P. O. Box 64, Helsinki, FIN-00014, Finland and RCN, Impps, Department of Biology, University of New Mexico, MSC 03-2020, 1 University of New Mexico, Albuquerque, NM 85131, fasmith@unm.edu

The extinction of dinosaurs at the K/Pg boundary was arguably the seminal event in the history of mammals, opening the door for their subsequent diversification into the wide range of lifestyles and body sizes seen today. Yet, only for North America has the trajectory and mode of body mass evolution been quantified. Here we compile and analyze data on maximum body mass at the ordinal level for each subepoch for each major continent. Beginning at the K/Pg, maximum size of terrestrial mammals increased near-exponentially, leveled off within ~25 Ma, and fluctuated only slightly through the Recent. There was remarkable congruence in the rate, trajectory and upper limit across continents, orders, and trophic guilds, despite differences in geological and climatic history, turnover of lineages, and variation in species composition. Our analysis suggests while the primary driver for the evolution of giant mammals was diversification to fill ecological niches subsequent to the dinosaur extinction, constraints on maximum size were set by environmental temperature and land area.

Session No. 77

Paleontology IV - Environmental Controls on Ecology and Evolution

Monday, 1 November 2010: 8:00 AM-12:00 PM

Room 605 (Colorado Convention Center)

Geological Society of America Abstracts with Programs. Vol. 42, No. 5, p.194

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