Updates to the caniform fauna (Carnivora, Caniformia) of the John Day Formation, Oregon, USA

Abstract

The John Day Formation of central Oregon preserves a diversity of Oligo-Miocene caniform carnivorans, many of which were first described from the formation. However, many historically important specimens lack detailed locality or stratigraphic information, complicating any analysis of faunal change through time. Here, we describe 16 new specimens of caniforms from the John Day Formation, most with precise stratigraphic information. We report multiple specimens of the amphicyonids Daphoenus Leidy, 1853, Paradaphoenus cuspigerus (Cope, 1878), and Temnocyon altigenis (Cope, 1878), all previously known from the formation. We also report the first definitive occurrence of the hesperocyonine canid Osbornodon Wang, 1994 from the John Day Formation and the first occurrence of the borophagine canid Otarocyon Wang, Tedford, and Taylor, 1999 from west of the Rocky Mountains. Two isolated postcranial elements are consistent in size and morphology with large amphicyonines but we cannot confidently assign them to this subfamily. Biostratigraphic trends in these taxa parallel those seen elsewhere in North America, although the turnover in large carnivorans observed at the Oligocene-Miocene boundary on the Great Plains might begin somewhat earlier in Oregon. The possible presence of a large amphicyonine would, however, mark a major temporal range extension for the subfamily and would be the oldest occurrence of this Eurasian taxon in North America.