Centennial Museum gecko logo

Desert Diary
Fossils/Dead Horses


About 70% of large species of mammals in North America were lost near the end of the Pleistocene. A combination of drastic climatic changes and the arrival on the continent of hunting man has led to a half century of controversy. Was it climate or was it man that did them in?

In any controversy, it's nice to have data—even though it's usually a lot simpler working from ignorance. A recent study by Dr. Dale Guthrie of the Institute of Arctic Biology shines some light on the matter. Horses were abundant and represented by a variety of species during the last ice age. Dr. Guthrie measured the length of one of the leg bones of one species as a stand-in for horse size and found a drastic shortening between about 25,000 years ago and the time of extinction around 12,500 years ago. Man is unknown in the study region until about 500 years later. The culprit? Apparently climate.

Alaska's a long way from the Chihuahuan Desert, but horses became just as extinct here. Climate or man?
pen and ink

Listen to the Audio (mp3 format) as recorded by KTEP, Public Radio for the Southwest.


Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.

Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.

Tooth of a fossil horse

A lower cheektooth of an fossil, extinct horse from Dry Cave, Eddy County, NM. Laboratory for Environmental Biology specimen. Scanned image by A.H. Harris.



Guthrie, R. D. 2003. Rapid body size decline in Alaskan Pleistocene horses before extinction. Nature 426:169-171.