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Desert Diary
Fossils/Range Changes


We all know that most individual animals move around a lot. What we sometimes forget, is that animals often shift their entire geographic ranges in response to changes in climate or vegetation. Paleontology sheds light on such biogeographical events, even if we don't always know the reasons for such shifts. In the Southwest, for example, we currently have two species of prairie dogs, Gunnison's and the Black-tailed. The first inhabits the roughly northwestern one-third of New Mexico, while the Black-tailed Prairie Dog historically inhabited the southeastern two-thirds and adjacent regions.

During the last part of the most recent ice age, Gunnison's Prairie Dog moved southeast to at least the Carlsbad area. This is understandable, because the climate at the time was cooler and moister. During a relatively mild period a bit earlier in the Pleistocene ice age, though, the same area was inhabited by either the Mexican Prairie Dog or a very closely related species. The Mexican Prairie Dog currently is limited to southern Coahuila and adjacent San Luis Potosí. Why the movement? We don't have a clue.
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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.