Coprolites in caves: late Pleistocene coprofaunas of the American Southwest and their significance

An extensive record of desiccated coprolites of diverse Late Pleistocene taxa is preserved in caves of the American Southwest. These include 21 caves in Arizona, 12 in Utah, six in Texas, four in New Mexico and one in Nevada. The majority of the coprolites represent herbivores, which is extremely rare for coprofaunas. There are two distinct regions characterized by cave coprolites - a northern realm (northern Arizona and southeastern Utah) is characterized by diverse morphologies of coprolites, and a southern realm (southern New Mexico and West Texas) where caves usually yield only coprolites of ground sloths (Castrocopros marlini) and coprolites of the packrat or woodrat Neotoma. The geographic distribution of the localities is governed by precipitation patterns and by the availability suitable cave-producing rock types. Desiccated coprolites can yield some of the highest quality radiocarbon dates, and these demonstrate extinctions of the megafauna between 11 and 12,000 yr B.P in the terminal Pleistocene. Macro-botanical specimens and pollen provide important evidence of individual diet and the local ecosystem. Castrocopros martini and coprolites of Neotoma are widespread, whereas coprolites of bighorn sheep Ovis canadensis and the extinct mountain goat Oreamnos harringtoni are common in caves in Arizona and Utah, but they are absent from Nevada and New Mexico. Coprolites of a large ruminant (Suaviocopros harrisi igen. et isp. nov.) and mammoths {Mammuthocopros allenorum) are restricted to Utah, which likely relates to topography. We advocate the discontinuation of the term "dung" for the cave coprolites and the use of binomial ichnotaxonomy for Pleistocene coprolites.