MATERIAL AND METHODS
Specimens examined in this study are curated at the University of California Museum of Paleontology (UCMP), Burke Museum at the University of Washington in Seattle (UWBM), and the John Day Fossil Beds National Monument (JODA). Specimen identifications and descriptions were facilitated by comparison to collections at the UCMP and UWBM, and literature descriptions and figures. During the fieldwork for this study, the author and colleagues measured sections and systematically collected fossils to document their stratigraphic occurrence.
The general stratigraphic context of the Tieton River area, shown in
Figure 2, is based on
Vance et al. (1987).
Stratigraphic sections were measured for the Milk Creek tuff and the Wildcat Creek beds where fossils were collected from prior fieldwork (Figure 3). Two additional sections measured along Thunder Creek record the complete sequence of the upper Wildcat Creek beds. Geological hand samples were collected systematically and identified by thin section and x-ray diffraction analyses. Geological descriptions follow
White and Houghton (2006) for grain size classifications,
Fisher (1961) and
Smith (1987) for rock descriptions, and
Mack et al. (1993) for paleosol classification.
Specimen measurements were made with Vernier-type dial calipers and are to the nearest 0.1 mm. Dental terminology follows
Tedford et al. (1996) for canids,
2008) for leporids,
Evander (2004) and
Prothero and Shubin (1989) for equids,
Prothero (2005) for rhinocerotids,
Gentry and Hooker (1988), and
Loomis (1925) for artiodactyls. Upper dentitions are designated with upper case letters, and lower case letters correspond to lower dentition.
North American Land Mammal Age designations follow
Tedford et al. (2004). Taxonomic occurrences in North America were gathered from
Janis et al. (1998) and supplemented by
Wang et al. (1999),
Tedford et al. (2004),
Stevens and Stevens (2007), and
Albright et al. (2008). Age estimates of North American fossil localities follow
Tedford et al. (2004) and are supplemented by
Albright et al. (2008).