TAXONOMY AND PALEOECOLOGY OF A LATE MIOCENE LOCALITY NEAR WELLS, NEVADA

We investigated a new Late Miocene fossiliferous locality in northeast Nevada. While primarily producing weathered fragments of vertebrate material, some identifiable material was produced. Of note is an exceptionally preserved fossil Carnivoran jaw. This small hypercarnivorous mandible was measured, described, compared, and diagnosed as a possibly novel species of hypercarnivorous mustelid similar to the extant genus Martes. While mustelids are not unknown from this region or time, this specimen is unique in both its overall size and its degree of preservation. The Wells localities are volcaniclastic-filled sequences, spanning an as of yet indeterminate range of time from the mid Miocene to Pliocene. Among the identifiable fossils, we see predominantly herbivores and large ungulates such as Parahippus and Teleoceras, but there is also evidence both of microvertebrates from teeth and postcrania produced from anthills and of larger carnivores through fossil fragments and bone processing marks on other fossils. Field observations; stratigraphic sequencing; and XRF, XRD, and other geochemical analyses were conducted. Our interpretations of these data point to fluvially reworked ash being the mechanism of burial of the mustelid fossil and of the diverse collection of fossils found along with it. This means that the fossils were not originally deposited in this landscape, but instead were transported from areas of higher topography, suggesting that the Basin and Range was already in place (or being created) by this time. Woody root traces and the copious amount of fluvially reworked ash implies a mosaic ecosystem of shrubby bushes and small trees to savannah situated in a depositional basin which experienced extensive ashfall. Taxonomic description of this hypercarnivorous mustelid and work done to place it within its paleoenvironmental context allows us to analyze the changing ecosystem of the Basin and Range region during the Late Miocene, a period when increasing topographic complexity drove a similar rise in ecosystem heterogeneity.