77 Paleontology IV - Environmental Controls on Ecology and Evolution
Monday, 1 November 2010
8:00 AM - 12:00 PM
Room 605
THE EVOLUTION OF GIANT MAMMALS: TRAJECTORY AND CONSTRAINTS on BODY SIZE OVER THE CENOZOIC
Paper number: 77-15
Program: Technical Sessions
Time: 11:30 AM – 11:45 AM
Authors
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Alison G. BoyerYale University, New Haven, CT
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James H. BrownUniversity of New Mexico, Albuquerque, NM
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Daniel P. CostaUCSC, Santa Cruz, CA
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S.K. Morgan ErnestLogan, UT
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Alistair R. EvansMonash University, Victoria, N/A
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Mikael ForteliusInstitute of Biotechnology, Helsinki, N/A
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Impps RcnUniversity of New Mexico, Albuquerque, NM
Abstract
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.