Urocyon progressus Stevens, 1965

TEDFORD R. H., WANG X. & TAYLOR B. E., 2009, Phylogenetic Systematics Of The North American Fossil Caninae (Carnivora: Canidae), Bulletin of the American Museum of Natural History 2009 (325), pp. 1-218 : 71-72

Urocyon progressus Stevens, 1965 Fig. 29F–G

Urocyon progressus Stevens (in part), 1965: 265, fig. 1A–B.

Urocyon progressus: Bjork, 1974: 25 , fig. 2a.

Type: UMMP 37157, left parietal bone, from Rexroad locality 3, Rexroad Formation (early Blancan), Meade County, Kansas. Figured by Stevens, 1965: fig. 1B.

Referred Material: From the type locality: UMMP 37158 , incomplete left tibia, figured and nominated paratype by Stevens (1965: fig. 1A), and V56767 , edentulous right partial maxilla and jugal, figured by Bjork (1973: fig. 2a). UCMP 112182 , right partial maxilla with P1 alveolus and P2–P4 and cranial fragment (fig. 29F–G) ; and UMMP 37156 , left M1, figured and designated a paratype by Stevens (1965: fig. 1C) .

Distribution: Only known from the early Blancan of Kansas.

Discussion: The diagnosis given by Stevens (1965: 265) cannot be used to characterize the species, and no additional material has been found that would permit a revision. As discussed by Stevens (1965: 265), the length of the type parietal bone (45.0 mm) is greater than that of the recent U. cinereoargenteus . Stevens also stated, ‘‘The maximum distance from the sagittal suture of the fossil parietal to the outer edge of the temporal ridge, at the greatest external curvature, is 12.8 mm.’’ This distance is within the range of the living gray fox but greater than that of U. minicephalus .

Bjork (1973: 25, fig. 2a) refered a partial maxilla and jugal to U. progressus . This specimen was from the type locality and Bjork stated that it may belong to the same individual as the type. The identification of Urocyon in the Rexroad Formation is further strengthened by Bjork’s observation that the ‘‘maxillojugal suture … is relatively straight as in Urocyon which distinguishes it from all other modern genera of canids.’’

The right maxillary fragment, UCMP 112182 (fig. 29F–G), also from the type locality, shows the presence of a small midlingual root on both P2 and P3. This variant is occasionally seen in living popula- +

Lingual view, reversed. G. Occlusal view, reversed. H–K. Urocyon galushai . H. JWTU (uncataloged), Cita Canyon beds, late Blancan, Texas. Upper first molar. Occlusal view, reversed. I–K. Type, associated maxillary fragment and ramus, F:AM 63104, Irvingtonian, Arizona. I. Occlusal view. J. Lateral view. K. Occlusal view, reversed. L–M. Urocyon cinereoargenteus scotti, AMNH (M) 136416, Recent, Texas. Occlusal views of upper and lower dentitions. N–O. Urocyon webbi , medial Hemphillian, Florida. N–O. Type ramus, UF 19407. N. Occlusal view, reversed. O. Lateral view, reversed. P–Q. Maxillary fragment, UF 19408. P. Occlusal view, reversed. Q. Lateral view, reversed.

tions of Urocyon (e.g., on left P3 of AMNH(m) 29448). The broken alveolus for P1 indicates a relatively large tooth, and the P1–P2 diastema is also long (5.0 mm). The P4 (length 11.8 mm) is short and broad with a continuous lingual cingulum and anterior cingulum and salient protocone as in Urocyon . Although it is larger than most living populations of Urocyon and smaller than the range of 53 individuals of Vulpes vulpes coming from Alaska to Georgia, it is approached by its near contemporary U. galushai from Arizona.

Because of the fragmentary nature and questionable association of the material assigned to this species, it cannot be diagnosed. However, the type parietal bone shows the separated and raised parasagittal crests that are a synapomorphy for Urocyon species , and the materials listed here from Rexroad locality 3 form a plausible association that may be confirmed by future discovery.