Untangling the prehistoric past isn't easy. A huge problem is when two or more major changes happen at the same time, making it difficult to know which is causing other changes. Sometimes, though, we get lucky, as with the fossil vampire bats. Cave sites in the Big Bend and in the bootheel of New Mexico document their presence late in the last ice age. These bats were larger than the living common species of vampire and have been considered to be a separate species, Stock's Vampire Bat. But what were they doing well north of the geographic range of the living species? Two possibilities have been considered—that they were dependent on the numerous large Pleistocene mammals and went extinct along with those animals some 11,000 years ago or that the changing climate did them in.
As chance would have it, the dates available suggest that they
disappeared just before the last major surge of the ice age. Cold winters probably
forced them from the area—the same factor that leaves our northern desert
vampire-free today.
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.
An upper arm bone (humerus) of the extinct Stock's Vampire Bat (Desmodus
stocki) from U-Bar Cave, Hidalgo County, NM. UTEP 5689-1-1.