79-5 THE EVOLUTION OF NORTH AMERICAN CAMELS: IMPLICATIONS FOR PALEONTOLOGICAL DATABASES

Abstract:

 Camels were one of the most common and diverse endemic mammals in the Oligocene through Neogene of North America. Yet their systematics have been a shambles for over a century, due to the lack of any comprehensive revision of the overall group—even though there are huge unstudied collections, such as the 20,000 specimens in the Frick Collection in the American Museum of Natural History in New York, that have been available for study since the 1970s. We have just published a complete systematic review of the entire group, and an updated cladogram and temporal and geographic range information of all the valid genera and species of North American camels. The old literature had over 60 named genera and over 200 named species. By contrast, we recognize only 40 valid genera of North American camels, with 79 valid species. Only one rare genus occurred in the late Uintan (late middle Eocene), then camels were completely unknown in the Duchesnean (latest middle Eocene), and relatively rare and low in diversity in the late Eocene (Chadronian). Only a handful of genera are known from the early Oligocene (Orellan to Whitneyan). By the late Oligocene (early Arikareean), camels began to diversify with Miotylopus, the gazelle-like Stenomylinae, plus primitive nothokemadines. In the early Miocene (latest Arikareean-Hemingfordian), camels underwent substantial diversification, with Oxydactylus, several genera of floridatragulines, miolabines, protolabines, and primitive aepycamelines, resulting in 15 genera in the late Hemingfordian, and 19 genera of camels in the late Barstovian-Clarendonian (middle Miocene), before reducing in diversity in the late Clarendonian-Hemphillian (late Miocene) and Pliocene. Only three genera remained in North America by the end of the Pleistocene, all of which vanished during the end-Pleistocene megafaunal extinction. Despite this absence of valid taxonomy, numerous studies have tried to draw paleoecological conclusions about Miocene land mammal communities with camels, one of the most important groups missing or inaccurately represented. The diversity curves drawn from outdated taxonomic sources are completely different from the true diversity curve, based on our current research. Many online databases, such as the Paleobiology DataBase (PBDB) or MIOMAP are grossly outdated their information about camels, with many invalid taxa. As long as research is based on these inaccurate taxonomic sources, the results are “garbage in, garbage out.”

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