Likely all of the fossils from our region referred to Urocyon are of the modern species, U. cinereoargenteus. Size is close to that for Vulpes macrotis and V. velox, but the "step" in the dentary (Fig. 1) is diagnostic as is the configuration of the temporal ridge on the frontals and parietals.
Fig. 1. Right dentary of Urocyon cinereoargenteus from U-Bar Cave. Note the "step" on the ventral border near the posterior portion of the dentary (this is not the angular process, which is missing at the far end).
Gray Foxes are common throughout our region in rough terrain, from low desert into coniferous forest. They seldom are found far from mountainous country. They are at home in wooded areas and are known as good climbers.
Several occurrences were listed in Harris (1993c) as Urocyon sp., but are included here as U. cinereoargenteus.
Fig. 1. Modern Urocyon cinereoargenteus skull and a fossil fragmentary left parietal from Isleta Cave No. 2. The surface below the temporal line in Urocyon is notably roughened. Because of the lighting and preservation, the roughness of the portion below the temporal line in the fossil is exaggerated, whereas the lighting and angle on the equivalent area of the modern specimen de-emphasizes the roughness.
Rancholabrean: Papago Springs Cave (Skinner 1942).
Early/Early-Mid Wisconsin: Balcony on Lost Valley (Harris 1993c: cf.); Lost Valley (Harris 1993c); Rm Vanishing Floor (Harris 1993c); Sabertooth Camel Maze (Harris 1993c).
Mid Wisconsin: Papago Springs Cave (Czaplewski and Mead et al. 1999); Pendejo Cave (Harris 2003); U-Bar Cave (Harris 1987).
Mid/Late Wisconsin/Holocene: Anthony Gap Cave (UTEP); Sierra Diablo Cave (UTEP).
Late Wisconsin: Blackwater Loc. No. 1 (Morgan and Lucas 2005); Camel Room (Harris 1993c); Cueva Quebrada (Lundelius 1984); U-Bar Cave 15-18 ka (Harris 1989); U-Bar Cave 18-20 ka (Harris 1989: cf.).
Late Wisconsin/Holocene: Conkling Cavern (Harris 1993c); Howell's Ridge Cave (Harris 1993c); Isleta Cave No. 2 (UTEP); Pendejo Cave (Harris 2003); Williams Cave (Ayer 1936).
Ayer 1936; Czaplewski and Mead 1999; Harris 1987, 1989, 1993c, 2003; Lundelius 1984; Skinner 1942; Morgan and Lucas 2005.
Similarity in size makes it difficult to separate post-cranial elements of Urocyon and Vulpes.
Sites. Mid Wisconsin-Holocene: Shelter Cave (Harris 1993c).
Last Update: 11 Mar 2013