Mammal extinctions, body size, and paleotemperature

Thomas M. Bown, Patricia A. Holroyd, Kenneth D. Rose

Research output: Contribution to journalArticlepeer-review

28 Scopus citations


There is a general inverse relationship between the natural logarithm of tooth area (a body size indicator) of some fossil mammals and paleotemperature during approximately 2.9 million years of the early Eocene in the Bighorn Basin of northwest Wyoming. When mean temperatures became warmer, tooth areas tended to become smaller. During colder times, larger species predominated; these generally became larger or remained the same size. Paleotemperature trends also markedly affected patterns of local (and, perhaps, regional) extinction and immigration. New species appeared as immigrants during or near the hottest (smaller forms) and coldest (larger forms) intervals. Paleotemperature trend reversals commonly resulted in the ultimate extinction of both small forms (during cooling intervals) and larger forms (during warming intervals). These immigrations and extinctions mark faunal turnovers that were also modulated by sharp increases in sediment accumulation rate.

Original languageEnglish (US)
Pages (from-to)10403-10406
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number22
StatePublished - Oct 25 1994

ASJC Scopus subject areas

  • General


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