Ecological changes in Miocene mammalian record show impact of prolonged climatic forcing

doi:10.1073/pnas.0805592105

Ecological changes in Miocene mammalian record show impact of prolonged climatic forcing

^†Museum of Paleontology and Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109;
^‡Peabody Museum, Harvard University, Cambridge, MA 02138;
^§Anthropology Department, University of New Mexico, Albuquerque, NM 87131;
^¶Department of Paleobiology, Evolution of Terrestrial Ecosystems Program, National Museum of Natural History, Smithsonian Institution, Washington, DC 20560; and
^‖Department of Geology and Geophysics, University of Utah, Salt Lake City, UT 84112

Contributed by Thure E. Cerling, June 14, 2008 (received for review January 27, 2008)

Abstract

Geohistorical records reveal the long-term impacts of climate change on ecosystem structure. A 5-myr record of mammalian faunas from floodplain ecosystems of South Asia shows substantial change in species richness and ecological structure in relation to vegetation change as documented by stable isotopes of C and O from paleosols. Between 8.5 and 6.0 Ma, C₄ savannah replaced C₃ forest and woodland. Isotopic historical trends for 27 mammalian herbivore species, in combination with ecomorphological data from teeth, show three patterns of response. Most forest frugivores and browsers maintained their dietary habits and disappeared. Other herbivores altered their dietary habits to include increasing amounts of C₄ plants and persisted for >1 myr during the vegetation transition. The few lineages that persisted through the vegetation transition show isotopic enrichment of δ¹³C values over time. These results are evidence for long-term climatic forcing of vegetation structure and mammalian ecological diversity at the subcontinental scale.

Footnotes

*To whom correspondence may be addressed. Email: cbadgley{at}umich.edu or cerling{at}earth.utah.edu
Author contributions: C.B., J.C.B., A.K.B., T.E.C., and D.P. designed research; C.B., M.E.M., S.V.N., and T.E.C. performed research; J.C.B. contributed new reagents/analytic tools; C.B., J.C.B., M.E.M., S.V.N., A.K.B., and T.E.C. analyzed data; and C.B. and A.K.B. wrote the paper.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/cgi/content/full/0805592105/DCSupplemental.