Alison Boyer, a new Research Assistant Professor in EEB, just published a paper in last week’s issue of Science.
The Evolution of Maximum Body Size of Terrestrial Mammals
Felisa A. Smith, Alison G. Boyer, James H. Brown, Daniel P. Costa, Tamar Dayan,
S. K. Morgan Ernest, Alistair R. Evans, Mikael Fortelius, John L. Gittleman,
Marcus J. Hamilton, Larisa E. Harding, Kari Lintulaakso, S. Kathleen Lyons,
Christy McCain, Jordan G. Okie, Juha J. Saarinen, Richard M. Sibly, Patrick R. Stephens, Jessica Theodor, Mark D. Uhen
Science 330, 1216 (2010);
The extinction of dinosaurs at the Cretaceous/Paleogene (K/Pg) boundary was the seminal event that opened the door for the subsequent diversification of terrestrial mammals. Our compilation of maximum body size at the ordinal level by sub-epoch shows a near-exponential increase after the K/Pg. On each continent, the maximum size of mammals leveled off after 40 million years ago and thereafter remained approximately constant. 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 ecological variation. Our analysis suggests that although the primary driver for the evolution of giant mammals was diversification to fill ecological niches, environmental temperature and land area may have ultimately constrained the maximum size achieved.