Rapid body size decline in Alaskan Pleistocene horses before extinction

About 70% of North American large mammal species were lost at the end of the Pleistocene epoch. The causes of this extinction-the role of humans versus that of climate-have been the focus of much controversy. Horses have figured centrally in that debate, because equid species dominated North America...

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Bibliographic Details
Published in:Nature 2003-11, Vol.426 (6963), p.169-171
Main Author: Dale Guthrie, R
Format: Article
Language:English
Subjects:
Alaska
Animals
Biodiversity
Body Constitution
Body size
Carbon dating
Climate
Climate change
Earth sciences
Earth, ocean, space
Endangered & extinct species
Exact sciences and technology
Fossils
Geographical distribution
Holocene
Horses
Horses - anatomy & histology
Horses - physiology
Human Activities
Humanities and Social Sciences
letter
Mammals
Models, Biological
multidisciplinary
Paleontology
Pleistocene
Predatory Behavior
Radiocarbon dating
Science
Science (multidisciplinary)
Time Factors
Vertebrate paleontology
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Summary:About 70% of North American large mammal species were lost at the end of the Pleistocene epoch. The causes of this extinction-the role of humans versus that of climate-have been the focus of much controversy. Horses have figured centrally in that debate, because equid species dominated North American late Pleistocene faunas in terms of abundance, geographical distribution, and species variety, yet none survived into the Holocene epoch. The timing of these equid regional extinctions and accompanying evolutionary changes are poorly known. In an attempt to document better the decline and demise of two Alaskan Pleistocene equids, I selected a large number of fossils from the latest Pleistocene for radiocarbon dating. Here I show that horses underwent a rapid decline in body size before extinction, and I propose that the size decline and subsequent regional extinction at 12,500 radiocarbon years before present are best attributed to a coincident climatic/vegetational shift. The present data do not support human overkill and several other proposed extinction causes, and also show that large mammal species responded somewhat individualistically to climate changes at the end of the Pleistocene.
ISSN:0028-0836
1476-4687
DOI:10.1038/nature02098