A new late Hemingfordian vertebrate fauna from Hawk Rim, Oregon, with implications for biostratigraphy and geochronology

ABSTRACT

The Hemingfordian North American Land Mammal Age is not well sampled, especially in the Pacific Northwest. Here we present both a description of a new fauna and two radiometric dates, 16.26 Ma and 16.44 Ma, constraining the Hawk Rim locality of central Oregon. Hawk Rim represents the first diverse late Hemingfordian fauna in the Northwest and is one of the stratigraphically lowest fossiliferous outcrops of the Mascall Formation. Much of Oregon was blanketed by Columbia River Flood Basalts during late Hemingfordian time, limiting not only outcrops but places for organisms to have survived. The site yields a taxonomically rich fauna sharing strong faunal similarity with the type locality of the Mascall but also containing taxa new to the formation and region. We describe occurrences of five genera of Artiodactyla, four genera of Perissodactyla, three genera of Rodentia, and six genera of Carnivora, with all but three new occurrences for the Hemingfordian of the Pacific Northwest. In particular, the carnivore fauna extends the geographic and temporal range of several carnivorans, and we describe a new hypercarnivorous mustelid, Watay tabutsigwii.http://zoobank.org/urn:lsid:zoobank.org:pub:B415069F-8BE6-4629-A872-5A640A644210

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Citation for this article: McLaughlin, W. N. F., S. S. B. Hopkins, and M. D. Schmitz. 2016. A new late Hemingfordian vertebrate fauna from Hawk Rim, Oregon, with implications for biostratigraphy and geochronology. Journal of Vertebrate Paleontology. DOI: 10.1080/02724634.2016.1201095.

ACKNOWLEDGMENTS

Funding for collection of fossils was made possible by a GeoCorps of America position with the John Day Fossil Beds National Monument. Funding for the U/Pb radiometric dating, as well as access to the fossil locality itself, was provided by the Bureau of Land Management. Funding necessary for the ⁴⁰Ar/³⁹Ar dating and for curation and identification of fossils was provided by an Evolving Earth Foundation grant. Additional funding was from University of Oregon's Department of Geological Sciences. Identifications were facilitated by a travel and research Welles Fund grant from the UCMP. Specimens for comparison were from the UOMNH, JODA, UCMP, Hagerman Fossil Beds National Monument, and the AMNH. D. Miggins, at Oregon State ran the ⁴⁰Ar/³⁹Ar dating and provided feedback concerning methods. The authors would like to thank the following individuals for advice concerning identification of specimens: J. Samuels, X. Wang, J. Orcutt, E. Davis, K. Maguire, D. Whistler, and B. Lander. This project would have been impossible without the aid of many field hands: UO Geology Field Camps 2010, 2011, and 2014, J. Orcutt, B. McHorse, R. Davis, J. Jacisin, W. Francis, A. Francis, M. Full, K. Paulson, J. McNabb, L. Edwards, K. Maguire, B. Shapiro, T. Huynh, G. Retallack, E. Bestland, and S. Olroyd. The authors thank B. Van Valkenburgh for handling the manuscript and the reviewers for their invaluable feedback as well.

Handling editor: Blaire Van Valkenburgh.