An attempt is made here to consider all Pleistocene vertebrate taxa from New Mexico and Trans-Pecos Texas recorded in the literature or in the Paleobiology Collection of the Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso. Taxa are given by currently accepted scientific names, but synonyms also are given where they have been used in the literature and are apt to cause confusion. Names of higher taxa of many groups are in a state of flux. The arrangement of the higher taxa here follows the Center for North American Herpetology's "Standard Common and Current Scientific Names" for amphibians and reptiles, the AOU Checklist for birds, and Mammalian Species of the World (Wilson and Reeder 2005) for mammals. In the case of the mammals, the on-line version is followed, where Rodentia is placed before Lagomorpha, rather than the printed version where the Rodentia is placed in volume 2 after all other taxa (presumably so that the rodents wouldn't be split between two volumes). In the case of mammals, taxonomic changes occurring after the publication date of Mammalian Species will be entered if there seems a high likelihood of general acceptance.
Following the higher taxonomy of chordates noted in the Center for North American Herpetology, the turtles are recognized as a separate taxonomic class, the Chelonia; the other class split from the Reptilia, the crocodilians (class Eusuchia), is not represented in the Pleistocene fossil record of our region.
Each taxon has its sites of occurrence mapped. No attempt has been made to be extremely accurate in placement of the dots representing the sites, the maps being designed largely to show the pattern of distribution. Site names, however, are listed in each account. Irvingtonian-age sites are shown with a green-centered dot; all other Pleistocene sites with a red-centered dot. In a few cases, records have been rejected and the site to which the taxon was assigned shown with a blue-centered dot.
In the site and taxon accounts, citations usually are to those deemed by me to likely be most useful to the reader. In many cases, this is to one of the summaries of Pleistocene taxa (such as Harris 1993c; Morgan and Lucas 2003, 2005). Occasionally, in addition to literature cited, other pertinent references may be listed to allow the reader to delve deeper if so inclined. In some cases, I have not personally reviewed these references.
Although most people can easily visualize horses, bison, and camels, relatively few have a mental image of a Bushy-tailed Woodrat or a Merriam's Shrew. Since a large portion of the Pleistocene fauna survives today, I have tried to include images of many of the taxa; hopefully, this will help some of the dried bones come alive in the minds of the viewer.
A "?" indicates considerable doubt regarding the identification. Usually this means that the (often fragmented) specimen is consistent with the taxon, but there are other taxa also consistent with the characters available; a sort of "playing the odds". A "cf." (abbreviation of the Latin word for "compare") indicates a likely correct identification, but one that is not certain. The listing of "?" or "cf." alone indicates the uncertainty applies to the species, but not the genus unless only the generic name is given; where the uncertainty applies to genus and species, the listing is given as ? or cf. gen. et sp. "UTEP" indicates that the taxon is represented by unpublished material in the Paleobiology Collection, Laboratory for Environmental Biology, or that some change in the published data has occurred.
Different ways of assigning specimens to a time span are used. The most general is "Pleistocene", meaning the time span cannot be narrowed further; subdivisions, however, sometimes are possible, such late Pleistocene. Somewhat more limited are the North American Land Mammal Ages (NALMA): Irvingtonian (1.9-0.3 Ma) and Rancholabrean (0.3 Ma-10 ka). In some cases, subdivisions are possible (e.g., early Irvingtonian). Most Pleistocene fossils are from the last of the glacial ages, the Wisconsin, and may be so recorded; again, sometimes with divisions possible. Age in years is possible in some cases where radiometric data are available.
Unfortunately, a number of sites have been disturbed. This is especially the case for cave sites, where pot-hunters or seekers after Spanish gold have disturbed the sediments without regard to stratigraphy. Also, many of the earlier excavated sites have less detailed stratigraphic notes than would be the case today, and it's now impossible to reconstruct the relationships. Because of such problems, some sites are recorded as, for example, "Late Wisconsin/Holocene", meaning that deposition is known to have occurred in both the late Wisconsin and the Holocene, and assignment to one or the other on stratigraphic grounds is not possible. In such cases, assignment to the Pleistocene may be made with considerable assurity for extinct forms and for taxa that now occur nowhere near the site; however, in the absence of reliable stratigraphic data, such taxa have lost an appreciable part of their value for interpretation. It also becomes problematical as to whether extant, local animals were present in the late Wisconsin or are present in the recovered fauna because of later occurrence.
I have been somewhat more daring (or, in the judgment of some, reckless) in assigning sites to limited time spans than were Morgan and Lucas (2005), and it should be recognized that there is a degree of danger in this as well as the possibility of illuminating short-term changes. I have made decisions as to the finer divisions of age of various cave faunas on the basis of stratigraphy where available and based upon my interpretation of the chronological distribution of Pleistocene biotas. Others may interpret the chronology differently; however, it is likely that where such designations as Mid Wisconsin, Late Wisconsin, or Early/Mid Wisconsin have been made, that at least assignment to the Wisconsin is firm. I have assigned Wisconsin faunas younger than 25,000 rcy (radiocarbon years) as Late Wisconsin; faunas judged to be between about 60,000 and 25,000 as Mid Wisconsin, and older than 60,000 are Early Wisconsin.
Literature.
Harris 1993c; Morgan and Lucas 2003, 2005.
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Last Update: 29 Apr 2009