Leptocyon tejonensis, TEDFORD R. H. & WANG X. & TAYLOR B. E., 2009

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 : 46-47

Leptocyon tejonensis , new species Figures 7, 18G–H; appendix 3

Type: LACM 16719 , right partial ramus with c and p2–m2 from the Bena Gravel (sensu Bartow and McDougall, 1984; Bartow, 1984) ; formerly referred to the Santa Margarita Formation) early Clarendonian, Comanche Point, South Tejon Hills ( CIT locality 303), Kern County, California .

Referred Material: From the type area Bena Gravel, Comache Point, south Tejon Hills ( CIT locality 303, except where indicat- ed), Kern County, California: LACM 47670 , left partial maxilla with P3–M2 ; LACM 16721 , right partial maxilla with P3 alveolus–M2 ; LACM 16714 , left partial maxilla with P4–M1 both broken ; LACM 16730 , right partial maxilla with P4 root and M1 broken–M2 ; LACM 16711 , right partial maxilla with M1 broken–M2 ; LACM 16728 , right M1–m2 ; LACM 16726 , right partial ramus with p2–m1 ; LACM 16718 , right m1 broken ; LACM 16729 , right partial ramus with p4 broken–m1 ; LACM 16725 , left m1 ; LACM 47669 , right partial ramus with c broken–m1 (p2 broken) ; LACM 16716 , left ramal fragment with m1 broken ; and LACM 16715 , a lower canine .

Distribution: At present known only from the type locality early Clarendonian of California.

Diagnosis: Derived characters that distinguish L. tejonensis from L. leidyi and L. vafer are shorter muzzle; premolars more closely spaced and anteroposteriorly shorter and taller with less prominent posterior cusp; p4 relatively wide for its length; m2 talonid length greater then 90% of trigonid; and metaconid taller than protoconid than in L. leidyi and L. vafer .

Description and Comparison: The dentition of L. tejonensis is within the size range of L. vafer (fig. 7). As indicated by the measurements (appendix 3) it is a homogeneous population sample, and the P4 and all molars are proportionally similar to those of L. vafer . The premolars, however, differ noticeably from those of all other species of Leptocyon in being more closely spaced, relatively shorter and taller with less prominent accessory cusps. The p4 is noticeably wide for its length (fig. 17). The m 2 in the type ( LACM 16719, fig. 18G–H), although approximately equal in size to that of L. vafer , has a long talonid and its metaconid is larger relative to the size of the protoconid than in other Leptocyon species. The metaconid in a second jaw ( LACM 16731) is somewhat smaller than that of the type but is still relatively large for Leptocyon . Both the short, tall, and simple premolars and the large m2 metaconid are suggestive of the condition in Metalopex or Urocyon . However, L. tejonensis lacks other important derived features that characterize Metalopex or Urocyon , including the m1 protostylid, strong m2 labial cingulum bearing a protostylid, and the more quadrate upper molars. Because of the absence of the above features, we have allocated this species to Leptocyon and view the anteroposteriorly short but tall premolars and enlarged m2 metaconid as having arisen in parallel with Metalopex and Urocyon species.

Tribe Vulpini Hemprich and Ehrenberg, 1832

The living foxes and fossil taxa attributed to living genera or phyletically related taxa can be grouped as we have indicated on our cladogram (fig. 65). These small canids are distinguished from all other Caninae in possessing a wide paroccipital process that is broadly sutured to the posterior surface of the bulla with a short and laterally turned free tip that barely extends below the body of the process. The presence of a metaconule and postprotocrista on M2 of vulpines represents the culmination of a reversal that began with late Leptocyon species to resume the form of the primitive canine M2.

Additional synapomorphies of the Vulpini include enlargment of the m2 metaconid so that it may exceed the protoconid in size, producing a convex lingual outline to the tooth, and further reduction of the parastyle of M1 and loss of its union with the preparacrista. Metalopex possesses these critical features and shares with Vulpes nasals that end anterior to the maxillary-frontal suture. Additionally, the Vulpini are distinguished from species of Leptocyon and united with the Canini (fig. 65) by common possession of three synapomorphies: loss of the medial cusplet on the I3; loss of the entepicondylar foramen on the humerus; and reduction of metatarsal I and loss of its phalanges.

The hypocarnivorous New World Metalopex and its living sister taxon Urocyon form a clade united by an elongate m2 talonid, highcrowned premolars, a protostylid on m1–m2, more quadrate upper molars, and the peculiar isolation of p2 by longer diastemata than separate other premolars along the very elongate rami of these taxa. These characters also unite these vulpines with the Old World Protocyon and Otocyon ( Tedford et al., 1995) .