Evolution of the Earliest Horses Driven by Climate Change in the Paleocene-Eocene Thermal Maximum

Authors

Ross Secord, University of Nebraska-LincolnFollow
Jonathan I. Bloch, Florida Museum of Natural History, University of FloridaFollow
Stephen G. B. Chester, Yale UniversityFollow
Doug M. Boyer, Brooklyn College, City University of New YorkFollow
Aaron R. Wood, South Dakota School of Mines and TechnologyFollow
Scott L. Wing, Smithsonian Museum of Natural HistoryFollow
Mary J. Kraus, University of Colorado, BoulderFollow
Francesca A. McInerney, Northwestern UniversityFollow
John Krigbaum, University of Florida, GainesvilleFollow

Document Type

Article

Date of this Version

2-24-2012

Comments

Published in Science vol. 335 no. 6071 (February 24, 2012), pp. 959-962; doi: 10.1126/science.1213859 Copyright © 2012 AAAS. Used by permission.

Abstract

Body size plays a critical role in mammalian ecology and physiology. Previous research has shown that many mammals became smaller during the Paleocene-Eocene Thermal Maximum (PETM), but the timing and magnitude of that change relative to climate change have been unclear. A high-resolution record of continental climate and equid body size change shows a directional size decrease of ~30% over the first ~130,000 years of the PETM, followed by a ~76% increase in the recovery phase of the PETM. These size changes are negatively correlated with temperature inferred from oxygen isotopes in mammal teeth and were probably driven by shifts in temperature and possibly high atmospheric CO₂ concentrations. These findings could be important for understanding mammalian evolutionary responses to future global warming.