Mammalian Biochronology of Late Cenozoic Basins of New Mexico: ABSTRACT

Abstract

The remains of fossil mammals have been collected from the late Cenozoic basins of New Mexico since the middle of the last century. Intensive work in the northern Albuquerque and Espanola basins in this country has resulted in large collections whose lithostratigraphic context has recently been published. Work on the biochronologic significance of these fossils has revealed that these thick basinal deposits preserve a record of the succession of mammalian faunas covering nearly the entire span of Miocene time. The record in each basin is not completely synchronous, but overlaps sufficiently so that the composite succession will eventually yield an important biostratigraphic standard for southwestern North America. It is possible to correlate this faunal succession and many other scattered fossil mammal occurrences within New Mexico with the geochrons of the North American Mammal Ages. Such correlations can be calibrated with a maximum precision of 1-2 m.y. and are thus of significance to historical geology. Geochronologically important fossil mammal remains are known in most of the late Cenozoic basins of New Mexico, but many of these have either gone unrecorded or have not been critically examined. Examples are: late Miocene through early Pleistocene successions in basins drained by the Gila River; early Miocene mammals from the northern Black Range; the Pliocene and Pleistocene faunas of the basins drained by the Rio Grande from Albuquerque south to the border; and early Miocene mammals from re-Santa Fe Group rocks in the Espanola basin. End_of_Article - Last_Page 571------------