Canis Linnaeus, 1758

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 : 104-119

Canis Linnaeus, 1758

Thos Oken, 1816.

Vulpicanis de Blainville, 1837 .

Lyciscus Smith, 1839 .

Sacalius Smith, 1839 .

Oxygous Hodgson, 1841 .

Lupulus Gervais, 1855 , not de Blainville, 1843, a nomen nudum.

Simenia Gray, 1868 .

Dieba Gray, 1869 .

Macrocyon Ameghino, 1881 .

Luppullella Hilzheimer, 1906.

Schaeffia Hilzheimer, 1906 .

Alopedon Hilzheimer, 1906 .

Stereocuon Mercerat, 1917.

Aenocyon Merriam, 1918 .

Megacyon von Koenigswald, 1940.

Oreocyon Krumbiegel, 1949 , not Oreocyon Marsh, 1872 , a creodont.

Dasycyon Krumbiegel, 1953 , replacement for Oreocyon Krumbiegel, 1949 .

Type Species: Canis familiaris Linnaeus, 1758 .

Included North American Species: Canis lupus Linnaeus, 1758 ; C. latrans Say, 1823 ; C. dirus Leidy, 1858 ; C. armbrusteri Gidley, 1913 ; C. lepophagus Johnston, 1938 ; C. edwardii Gazin, 1942 ; C. cedazoensis Mooser and Dalquest, 1975 ; C. ferox Miller and Carranza-Castañeda, 1998 ; C. thöoides , new species and C. feneus , new species.

Distribution in North America: Late Hemphillian to Recent (late Miocene to Recent).

Revised Diagnosis: Synapomorphies that unite species of Canis with those of Cuon , Lycaon , and Xenocyon and serve to distinguish them from all other members of the Canina are: frontal sinus large, penetrates postorbital process and extends posteriorly to frontoparietal suture; supraoccipital shield triangular in shape, inion usually pointed and overhanging condyles; I3 crown and cingulum enlarged; superior fossa of angular process for median pterygoid expanded; p4 with second posterior cusp; m1 entoconid united with hypoconid by cristids; and forelimb long relative to hindlimb.

Canis is primitive relative to Cuon , Lycaon , and Xenocyon in its relatively larger canines and lack of such dental adaptations for hypercarnivory as m1–m2 metaconid and entoconid small or absent; M1–M2 hypocone small; M1–M2 lingual cingulum weak; M2 and m2 small, may be single-rooted; m3 small or absent; and wide palate.

Discussion: The oldest remains from North America that can definitely be attributed to the genus Canis are those described below from the late Hemphillian of western North America. Previously referred to Canis in the Late Miocene of western Europe was the holotype maxillary fragment and a subsequently referred lower carnassial ( Pons-Moya and Crusafont, 1978) of Canis cipio Crusafont, 1950 , from late Turolian deposits of the Teruel Basin of Spain. The fragmentary nature of these remains limits observation of most of the derived features of Canis or the Canis group, and, accordingly, the generic allocation of C. cipio has been recently questioned ( Rook, 1992), and we provide a further analysis in the conclusions of this work.

Canis ferox Miller and Carranza-Castañeda, 1998 Figures 37A–G, 38A–Q, 40, 43, 44, 52; appendices 2–4

Canis lepophagus: Bjork, 1970: 13 .

Canis davisi: Gustafson, 1978: 36 .

Canis lepophagus (in part): Nowak, 1979: 71.

Canis ferox Miller and Carranza-Castañeda, 1998: 549 .

Type: IGM 1130, nearly complete skull, highly fragmented, but little distorted, with badly eroded left and right P3–M2, associat- ed, left ramus better preserved, with c alveolus, p1 broken, p2 alveolus, p3, p4 broken, m1–m2, m3 alveolus, atlas fragment, partial 3rd cervical, three fragmented thoracic vertebrae, left scapula, nearly complete left and right humeri, fragmented of right ulna, right metacarpals IV and V, nearly complete left femur, patella, nearly complete right tibia, left calcaneum, cuboid, navicular and cuneiform, left and right proximal ends of 2nd metatarsals, two proximal, two medial, and five distal phalanges. Figured by Miller and Carranza-Castañeda (1998: figs. 4, 5). From the Rancho San Martin locality (GTO- 42), 2 km northeast of the village of Rancho Viejo and 12 km north of the city of San Miguel Allende, Guanajuato, Mexico, in the lower part of the Rancho Viejo beds (late Hemphillian).

Paratype: F:AM 49298, skull with right I1– I3, C–P1 alveoli, P3–M2 and left I1–P1 alveoli, P2–M2; isolated left I3 and P1; right and left mandibular rami, with i3–m3, axis and 3rd cervical, one thoracic and two caudal vertebrae, and fragment of pelvis from the Golgotha Water Mill Pothole site (late Hemphillian), from unnamed deposits in Spring Valley, near Panaca, Lincoln County, Nevada,

Referred Material: Optima Local Fauna (late Hemphillian), near Guymon, Texas County, Oklahoma: F:AM 62955, left isolat- ed P4; and F:AM 30468, left isolated M1.

Leyden loality, Chamita Formation (late Hemphillian), Rio Arriba County, New Mexico: F:AM 27388, left partial ramus with p3–p4 alveoli and m1–m2.

Bird Bone Quarry, Big Sandy Formation (late Hemphillian), near Wikieup, Mohave County, Arizona: F:AM 63032, palate with incisor alveoli, left canine and P1 alveoli, right P2–P3 broken, left P2–M1, right P4, M1 broken, M2 (fig. 38A); F:AM 63035, right and left (fig. 38C) rami with right teeth broken, left c–m2; F:AM 73606, left partial ramus with c broken, p1 alveolus, p2–p4, m1 broken; F:AM 72556, left humerus; F:AM 72566, left radius; F:AM 72569A, left ulna; F:AM 72581, left metacarpal II; F:AM 72577, metacarpals II, III, and incomplete metacarpal IV; F:AM 72572A, left tibia; F:AM 72572C, left tibia; F:AM 72572B, left tibia; F:AM 72610, left metatarsal II; F:AM 72585B, left metacarpal II; F:AM 72611, left metatarsal II; F:AM 72587D, left metatarsal II; F:AM 72589B, left metatarsal IV; and F:AM 72589A, right metatarsal IV.

Clay Bank Quarry, Big Sandy Formation (late Hemphillian), near Wikieup, Mohave County, Arizona: F:AM 63060, right partial ramus with c–m2; 61612*, left partial ramus, with p4–m1 broken, m2, and m3 alveolus.

Gray’s Ranch Quarry stratum 3, Big Sandy Formation (late Hemphillian), near Wikieup, Mohave County, Arizona: F:AM 63059, left partial ramus with p1 alveolus, p2, p3 alveolus p4–m1, m2 alveolus; F:AM 63061, right and left rami with right p3–p4, m1–m3 alveoli, left m1–m2, m3 alveolus (fig. 38B); and F:AM 72572A, left tibia.

Redington Quarry, Quiburus Formation (late Hemphillian), northwest of Redington on the west side of the San Pedro River Valley, Pima County, Arizona: F:AM 75848, crushed skull with I3 (alveolus)–M2 and right ramus with c–M2 (broken) (p1 alveolus–p2 broken); F:AM 75821, left ramus with c (broken)–m3 (P1 alveolus and m1 broken), probably same individual as F:AM 75848; F:AM 75822, right partial ramus with m1–m2.

Old Cabin Quarry, Quiburus Formation (late Hemphillian), near Redington, Pima County, Arizona: F:AM 75847, crushed left and right maxillae with I3–M2 (P2–P3 broken); and F:AM 75819, left and right partial rami with c (broken)–m3 (p1–p2 and p4 broken) and right maxillary fragment with M1 (broken)–M2.

Yepomera, CIT locality 275 (latest Hemphillian), Chihuahua, Mexico: LACM 30205, left m1.

Devils Nest Airstrip, UNSM locality Kx- 113, Ogallala Group (late Hemphillian), Knox County, Nebraska: UNSM 1022-73, paratial skull including most of the frontal, parietal, and interparietal region (fig. 38E– F), broken basioccipital region, incomplete premaxilla and maxillary fragment with I1–I2 alveoli, and I3–C, and right and left partial maxillae with P3 (broken), P4 (alveolus), and P4–M2 (fig. 38D).

Rexroad Local Fauna, locality 3, Rexroad Formation (early Blancan), Rexroad Ranch, Meade County, Kansas: UMMP 37132, P4, M1 broken, and p3. This was referred to C. lepophagus by Nowak (1979: 72).

Bender Local Fauna, above massive caliche in the Rexroad Formation and below the Angel member of the Ballard Formation, Rexroad Formation (early Blancan), Bender Ranch, Meade County, Kansas: UMMP V60942 , right and left partial rami with p2, m1 (broken)–m2 (all other teeth represented by alveoli or roots), and associated isolated teeth including two canines, premolars, m1, and tooth fragments.

Hagerman Fauna, Glenns Ferry Formation (medial Blancan), Twin Falls County, Idaho: UMMP V452222, left partial ramus with c (alveolus)–p4 (p1 alveolus), USGS Cenozoic locality 19213 ( DWT 427); UMMP V53910 , right and left rami with incisors alveoli–m2 (p1 alveolus), UMMP locality UM-Ida 70-65 (fig. 38K–L, figured by Bjork, 1970: fig. 8c); UMMP V54995 , right partial maxilla with P4, UMMP locality UM-Ida 19- 65; UMMP V56282 , right ramal fragment with m1 (broken) m2–3 (alveoli), UMMP locality UM-Ida 80-65; UMMP V56401 , left partial maxilla with P4–M2, UMMP locality UM-Ida 11-67 (figured by Bjork, 1970: fig. 8b); and UMMP V52280 , left partial maxilla with P4–M2 (fig. 38J), USGS Cenozoic locality 20765. These specimens had been referred to C. lepophagus by Bjork (1970) and Nowak (1979: 70–71).

White Bluffs Fauna (early Blancan), 35– 45 ft above White Bluffs Tuff, Ringold Formation, Franklin County, Washington: UWB 28747*, lower canine fragment; UWB 402289*, lower canine fragment; UWB 40393*, m1; UWB 35114*, P4; UWB 40288*, P4; UWB 40393*, m1, UWB 40393*, m1; UWB 41969*, m1; UWB 33061*, p4 (referred to ‘‘ Canis ’’ davisi by Gustafson, 1978: measurements table 12). Rankin Canyon, LACM locality 4574, Franklin County, Washington: LACM 143527*, right ramus with p1–p2 alveoli, p4–m1; Ringold Formation, LACM locality 588D: LACM 143528*, left ramus with m1 and partial alveolus of m2; LACM 143529*, left m1.

Lisco Member of the Broadwater Formation (medial Blancan), Garden County, Nebraska: UNSM 26107, partial skull (fig. 38G–I) with I1–P3 (alveoli) and P4– M2, locality Gd-13, Lisco Quarry 4; UNSM 26114, right and left partial rami with c (broken)–m3 (alveolus), p1 and p3 (alveoli), Gd-12, Lisco locality C, Quarry 1; UNSM 4258, right and left partial rami with p2–m2, Gd-14, Lisco locality C, Quarry 2; UNSM 4261, right ramus with p2 (alveolus)–m2 (m3 alveolus) (fig. 38M–N), partial scapula, humerus (fig. 380), partial ulna, radius (fig. 38P), incomplete metacarpal II, one complete (fig. 38Q) and one partial metacarpal III, incomplete metacarpal IV, metacarpal V, partial pelvis, partial femur, partial tibia, calcaneum, astragalus, metatarsal IV, phalanges, vertebrae, and fragments, Gd-14, Lisco locality C, Quarry 2; UNSM 88522*, right ramus with i3, c, p1 (alveolus), p2–p3, m1–m2, and possibly associated anterior part of skull with complete, but largely disarticulated, dentition, Gd-14, Lisco Quarry 2; and UNSM 88528*, palate with right and left P4, M1, M2 and associated left ramus with p1–p3, p4 (root), m1 (broken), m2–m3, Gd-14, Lisco Quarry 1. Nowak (1979: 72) referred UNSM 26107 and 26114 to C. lepophagus .

Distribution: Late Hemphillian of Mexico, New Mexico, Arizona, Nevada, Oklahoma, and Nebraska, early Blancan of Washington, early to medial Blancan of Kansas, and medial Blancan of Idaho and Nebraska.

Revised Diagnosis: The expanded frontal sinus, enlargement of the angular process for insertion of the superior ramus of median pterygoid, triangular shape of supraoccipital shield, and union of the parasagittal crests anterior to the frontoparietal suture differentiates C. ferox from Eucyon sp. ; other features such as the size of skull and skeleton stand intermediate between E. davisi and C. lepophagus .

Discussion: Miller and Carranza-Castañeda (1998) proposed C. ferox for an associated skull, ramus, and partial skeleton from the late Hemphillian of central Mexico following comparison with the E. davisi sample at the American Museum of Natural History and the type and topotypic sample of C. lepophagus in the Panhandle Plains Museum, Canyon, Texas. They thought that C. ferox was closer to C. lepophagus , differing primarily in smaller size and in proportional relationships of the skull, dentition, and some elements of the skeleton. We agree with this conclusion and add a number of other samples from the Great Plains, Washington, and Idaho that similarly show such intermediate features.

Because of the lack of uncrushed skulls of North American E. davisi , it is difficult to compare the skull features with those of the type and paratype of C. ferox . However, the skulls referred to E. davisi from the Chinese Pliocene ( Tedford and Qiu, 1996) are used to provide supplementary data. It is evident that the two skulls (F:AM 49298 and 75848) of C. ferox are larger and more massive with a wider muzzle than those of E. davisi . The width of the braincase and especially that of the postorbital constriction of C. ferox are markedly narrower relative to the length of the skull (fig. 43). The frontal sinus cavity is narrow but extends to the end of the long narrow postorbital constriction. A septum partially separates the frontal sinus of the postorbital process from the main body of the frontal sinus. In C. ferox , the sagittal crest is stronger, its parasagittal components unite well before the frontoparietal suture, and the supraoccipital is triangular in outline, narrower, and projects more posteriorly than in E. davisi . A palate and partial cranium of C. ferox of late Hemphillian age from Nebraska ( UNSM 1022-73, fig. 38D–F) can be compared with that of E. davisi (F:AM 63005, fig. 34A–C) from the late Hemphillian deposits near Wikieup, Arizona. The frontal sinuses are similar in size, as they are also to an early Blancan skull ( UNSM 26107, fig. 38I) from the Lisco Member of the Broadwater Formation in Nebraska. In both of these specimens the inion is fan-shaped as in E. davisi , but in the type of C. ferox the inion is more triangular and may have overhung the condyles as in some individuals of C. lepophagus .

Among the canid dentitions of late Hemphillian age from Wikieup, Arizona, there is a group that is significantly larger than those referred to E. davisi (fig. 40). Judging by the size of the canine teeth, both sexes are included in the sample and thus the larger size of these specimens as a whole is not attributable to sexual dimorphism. Although many of the lower carnassials from Arizona are worn, the talonids, as in most E. davisi , lack the transverse crest between the entoconid and hypoconid, and there is only a low hypoconulid shelf. This primitive condition is also occasionally present in specimens of C. lepophagus of Blancan age. Otherwise, the specimens are morphologically intermediate between those of E. davisi and C. lepophagus . Furthermore, the premolars are extremely elongate and vary from slender (F: AM 63060) to robust (F:AM 63035, fig. 38C). The premolars are more elongate and generally more robust than those of contemporary specimens of E. davisi , but again within the size range of those of C. lepophagus . The mandibular ramus is also more robust, and the horizontal ramus is deeper than in E. davisi . The angular process of the mandible is similar to that of E. davisi and less robust than that of C. lepophagus with a smaller fossa for the inferior ramus of the median pterygoid muscle.

Dentitions of C. ferox from the Lisco Member (medial Blancan) of the Broadwater Formation at the Lisco Quarries in Garden County, Nebraska, are, on average, smaller and less robust than those of C. lepophagus from the referred Lisco Member of the Broadwater Formation farther west in Morrill County, Nebraska. In both size and morphology the dentition from the Lisco Quarries closely resembles those described by Bjork (1970: 13) from the Hagerman Fauna (medial Blancan) and attributed by him to Canis lepophagus . Some of the better specimens of these Hagerman C. ferox are included in the hypodigm here, and according to Bjork, the total sample consists of a group of 19 individuals with a stratigraphic range of 320 feet in the Glenns Ferry Formation. That portion of the Glenns Ferry section lies in the later part of the Gilbert Chron (4.2–3.6 Ma) of the geomagnetic polarity time scale ( Neville et al., 1979, recalibrated by Cande and Kent, 1995). Because of the favorable comparison of the Hagerman Fauna canids with those from the Lisco Member from Garden County, the latter are tentatively considered as members of a medial Blancan fauna. Voorhies and Corner (1986: 75) also concluded that the fauna of the Lisco Quarries was significantly older than the fauna of the Broadwater Quarries and of ‘‘early Blancan’’ age following comparison of Megatylopus (?) cochrani with similar forms from Washington (Ringold Formation) and Kansas (Rexroad Formation). They also report the presence of Pliopotamys minor in the Lisco Quarries, an immigrant arvicoline rodent typical of Blancan III faunal unit of Repenning (1987) that includes the Hagerman and younger Ringold (Taunton) faunas also paleomagnetically correlated with the later part of the Gilbert Chron.

The minimum size and the mean value of the m1 and m2 of C. ferox from the Rexroad Formation, the Glenns Ferry Formation, and the Lisco Quarries of the Broadwater Formation in Garden County are smaller than those of the larger topotypic population of C. lepophagus from Cita Canyon (late Blancan) of Texas (fig. 40). The 95% confidence interval for the length of the m1 and m2 partially overlaps the lower end of the interval of the Cita Canyon population. In contrast, the C. lepophagus samples from the Broadwater Quarries in Morrill County, Nebraska, are similar in size (appendix 3) and morphology of the skull and dentition to the topotypic sample of C. lepophagus from the late Blancan of Cita Canyon.

Further inspection of the dentitions from the Hagerman Fauna and the Lisco Quarries of Garden County indicates that not only are they smaller than that of C. lepophagus from Cita Canyon, but in some ways the morphology recalls that of the dentition of E. davisi . Specimens from both the Hagerman Fauna and the Lisco Quarries in Garden County have slender premolars similar to those of E. davisi . The P4 has the protocone anterolingually directed, and the anterolabial shoulder projects more anteriorly and is less rounded than is generally found in C. lepophagus from Cita Canyon. The foregoing features result in the anterior border of the P4 being deeply notched. In some specimens ( UMMP V56401 and V52280 , fig. 38J), the M1 is anteroposteriorly long relative to its transverse diameter as in E. davisi , a condition occasionally seen in C. lepophagus from Cita Canyon ( WTC 530 and 560J). Furthermore, the M1 paracone and metacone are relatively low-crowned with a strong labial cingulum and a small parastyle. The hypocone is strong and continuous, with the lingual cingulum joining the labial cingulum at the base of the paracone. The lower carnassial is intermediate in size and morphology between E. davisi and C. lepophagus , with the entoconid and hypoconid either separate or weakly joined by a transverse crest. A distinct hypoconulid is absent although a small hypoconulid shelf may be present.

Limbs referred here to C. ferox are longer (appendix 4) and more robust than those of E. davisi (compare fig. 38O–Q with fig. 39A– B, D), and for the most part are within the size range of those of C. lepophagus from Cita Canyon (fig. 52). The unassociated limbs imply that the relative proportion of elements (fig. 52) are closely similar to those of C. lepophagus and differ from C. edwardii and C. latrans .

Thus, this heterogeneous late Hemphillian to medial Blancan sample, which is morphologically intermediate between the Hemphillian E. davisi and late Blancan C. lepophagus , is predominantly characterized by plesiomorphic characters. The dentition is larger but morphologically similar to that of E. davisi and compares favorably with only a few of the Blancan dentitions from Cita Canyon of C. lepophagus . The expanded frontal sinus, enlarged angular process, triangular supraoccipital shield, and sagittal crest originating on the frontals are characters shared with C. lepophagus and features that distinguish C. ferox from E. davisi .

Canis lepophagus Johnston, 1938 Figures 40, 41A–G, 42A–J, 43, 44, 52; appendices 2–4

Canis lepophagus Johnston, 1938: 383–390 , pls. 1–3.

Canis latrans lepophagus: Giles, 1960: 369 .

Type: WTUC 881, skull with I1–M2 (fig. 41A–C) from North Cita Canyon (type locality of the Cita Canyon beds), stratum no. 2, Ogallala Group (late Blancan), Randall County, Texas.

Referred Material from Type Locality: WTUC 722 , skull with I1–P4 (alveoli or broken), M1–M2, and ramus with c–m2 (il– i3 and m3 alveoli or broken) ; WTUC 760 , skull with I1 (broken)–M2 (fig. 41D–F) ; WTUC 2523 , skull with P1–M2, C alveolus broken and provisionally associated left ramus: WTUC 2527 , pl (alveolus healed), p2 broken, and p3–m3 ; WTUC 558 , mandible with incisor alveoli, c–pl broken, p2–m3 ; WTUC 558 a, right ramus with c–pl (alveolus), p2 (broken)–m3 (alveolus) ; WTUC 558 b, left ramus with i1–i3 (alveoli), c (broken), pl (alveolus healed), p2–p4 (alveoli), and m1 (broken)–m3 (alveolus) ; WTUC 558 c, left ramus with pl (alveolus healed), p2, p3 (alveolus), p4–m2 (broken), and m3 (alveolus) ; WTUC 558 d, i1 (alveolus)–c alveolus, p2–m2 ; WTUC 560 i, right maxilla with P4–M2 (alveolus) ; WTUC 560 j, right maxilla with P3 (alveolus)–M2 ; WTUC 560 k, left m1 ; WTUC 5601 , right ramus with p4 alveolus, m1 and m2 alveolus ; WTUC 530 , left maxilla with M1–M2 ; WTUC 1038 , left maxilla with M1–M2 ; WTUC 2495 , left isolated p4 ; WTUC 1027 a, right and left rami with i2 (broken)–m3 (alveolus) ; WTUC 1027 b, left ramus with i1–i2 (alveoli) and i3– m3 (m1 broken) ; WTUC 1027 c, right ramus with i1–i3 (alveoli) and c–ml (broken) ; WTUC 2287 , right and left rami with c–m2 ; WTUC 2423 , right ramus with p4–m2 and m3 alveolus ; WTUC 2494 , right ramus with p4 (broken)–m1 (broken) and m2–m3 (alveolus) ; WTUC 2631 , left ramus with p4 (broken)–m2 ; WTUC 2717 , right ramus with c–m3 (alveolus) ; WTUC 1027 d, right ramus with i1–c (alveoli) and p1–m3 (fig. 42B–C) ; WTUC 559 , left ramus with i1 (broken)–m3 and c broken ; WTUC 559 a, right ramus with i1–i3 (alveoli) and c (broken)–m3 (alveolus) (fig. 42A) ; WTUC 560 , right and left rami with c–m1 and m2–m3 (alveoli) (fig. 42D–E) ; WTUC 560 a, right ramus with i2–i3 (alveoli), c broken, p1–p2, p3 root, p4–m1 (broken), m2 (alveolus), and m3 (broken) ; WTUC 560 b, right ramus with p3–m3 (alveolus) ; WTUC 560 c, right ramus with il–i3 (alveoli), c–p3 (broken), and p4–m1 (broken) ; WTUC 560 d, right ramus with p3 (broken and alveolus), p4 (alveolus), m1–m2, and m3 alveolus ; WTUC 560 e, left ramus with p4 (alveolus) and m2 ; WTUC 560 f, left ramus with p1 (broken) and m3 (alveolus) ; WTUC 560g, right and left rami with i1–i3 (alveoli), c (broken), p2 (broken), p3–m1, and m2–m3 (alveoli); WTUC 560 h, left ramus with c (broken), p2, m2, and alveoli ; WTUC 1531 , right isolated M1 ; WTUC 560m, right ramus with m2–m3 (alveolus) ; WTUC 560 n, right ramus with m1 (broken)–m2 ; WTUC 560 o, right isolated m2 ; WTUC 560 p, right isolated m2 ; WTUC 2532 , left ramus with m1–m2 ; WTUC 2532 a, right ramus with p3 (alveolus broken)–m1 (alveolus) and m2 ; WTUC 2530 , left isolated m1 ; JWT 1062m, radius ; CWT 2446 , radius and ulna ; CWT 2574 , radius ; ulna; CWT 2573 , femur ; CWT 2525 , partial humerus ; JWT 1908 , partial humerus ; JWT 573 , tibia ; CWT 2526 , tibia ; JWT 614 , metacarpal II ; no number, metacarpal III; CWT 2411 , metacarpal II ; JWT 565 , metacarpal IV ; JWT 565 , metacarpal IV ; JWT 614 , metacarpal IV ; JWT 565 , metacarpal V ; CWT 2446 , metacarpal V ; CWT 2430 , metatarsal II ; CWT 2572 , metatarsal II ; CWT 2442 , metatarsal III ; CWT 2572 , metatarsal III ; JWT 565 , metatarsal IV ; JWT 565 , metatarsal V ; CWT 2442 , metatarsal V ; CWT 2572 , metatarsal V ; and JWT 614, metatarsal V.

Rita Blanca beds, between 11 and 13 km southeast of Channing (late Blancan), Oldham County, Texas: F:AM 62986, left isolated P4; F:AM 99374, metatarsal V, from Bevins Pit 1; F:AM 62987*, right and left partial rami with c, p2, and alveoli, from Proctor Pit B.

Red Light Local Fauna (late Blancan), Love Formation , Hudspeth County, Texas: TMM 40664-3 *, right ramus, c, p1–p4 alveoli ; TMM 40664-9 *, left ramus, p1 roots ; TMM 40664-11 , part of right radius and right metacarpal II .

Camp Rice Formation (late Blancan or early Irvingtonian), Mesilla Basin, south of Las Cruces, Doña Ana County, New Mex- ico: F:AM 22251*, right partial ramus with p1 alveolus, p2, p3–p4 both broken, wellworn m1–m2, and m3 root.

Sand Draw Fauna, east of Jackrabbit Hill, Keim Formation (medial Blancan), Brown County, Nebraska: UMMP V57321 , fragments of skull, right premaxilla, and maxilla with I1–M1 (broken) (I2 and P1 alveoli and I3, P2–P3 broken), right and left rami with c– m3, p1 alveolus (figured by Skinner and Hibbard, 1972: fig. 48).

Lisco Member, Broadwater Formation (late Blancan), locality Mo-5, Morrill Coun- ty, Nebraska: UNSM 26112, crushed skull with I1–I3 (alveoli), c (broken), P1–P2 (alveoli), and P3 (broken)–M2; UNSM 26111, crushed skull with I1–IC (alveoli) and P1–M2; UNSM 26113, left partial maxilla with P4–M2 (fig. 42J); UNSM 26116, left ramus with i3, c–p1 alveoli, p2, p3–p4 alveoli, m1–m2, m3 alveolus (fig. 42F– G); and UNSM 4260, right partial ramus with c–p2 (alveoli) and p3–m2 alveolus (fig. 42H–I).

Big Spring Local Fauna (late Blancan), Long Pine Formation, UNSM locality Ap 103, Antelope County, Nebraska: UNSM 46893, right ramus with p4, m1–m2, m3 alveolus; and UNSM 52306*, fragment of left ramus with p1 (root), p2–p3 (root).

Meade County State Park, Deer Park Local Fauna, Missler Member, Ballard Formation (late Blancan), Meade County, Kansas: UMMP V31945 *, two right and one left isolated, broken M1s. Other specimens from the same locality in the KU collections referred by Nowak (1979: 71–72).

Tehama Formation (late Blancan), Beck Ranch site 1, UCMP V3022, Tehama County, California: UCMP 29828, m1 (attributed to Canis sp. by VanderHoof, 1933).

Double Butte, 6.25 m below the Double Butte Quarry, Panaca Formation (early Blancan), Lincoln County, Nevada: F:AM 49295, crushed skull with I1–IC alveoli, P1– P3 broken and P4–M2 (fig. 41G), and limb fragments.

Glenns Ferry Formation (late Blancan): LACM 1246, left partial ramus with p2 (alveolus)–m2, CIT locality 118, Grandview Fauna, 21 km northwest of Grandview, Owyhee County, Idaho. LACM 1343, left partial ramus with c and p1 (alveolus)–m3 alveolus (p2 and m2 alveoli) from CIT locality 122, Flatiron Butte Local Fauna, Barker Ranch, south side of Snake River, 6 km east of Bruneau-Mountain Home Bridge, Owyhee County, Idaho.

Santa Fe River, site 1A (late Blancan), Columbia and Gilchrist counties, Florida: UF 10424, right ramus, I1–I3, c, p1, alveoli, p2–p4, m1–m3; UF 10423, left ramus, p4– m1; UF 10837, left ramus, c–p2 alveoli, p3, p4–m1 alveoli; UF 10833*, edentulous right ramal fragment c–p4 alveoli; UF 10836*, edentulous right ramal fragment with c–m1 alveoli ( Kurtén, 1974: 6, table 4).

Saint David Quarry, Saint David Formation (late Blancan), 4 km east of Saint David, Cochise County, Arizona: F:AM 63091, crushed partial skull with P4–M1 and all alveoli; F:AM 72612, left M1, Benson area, Saint David Formation (late Blancan), Cochise County, Arizona.

Tusker Fauna, 111 Ranch at Dry Mountain locality (late Blancan) near Safford, Graham County, Arizona: F:AM 63102*, skull fragments including partial premaxilla* and maxilla with C–P3 alveoli and broken, and calcaneum; F:AM 63103*, left partial ramus with p3 (broken)–m1 (broken).

El Golfo de Santa Clara, northwestern Sonora, Mexico (Blancan): IGM 13103* (Yuma), partial right ramus with p3–p4 (broken), m1–m2, m3 alveolus.

Distribution: Early Blancan of southern Nevada; medial Blancan of Nebraska; late Blancan of Texas, Kansas, Nebraska, California, New Mexico, Arizona, Idaho, Florida, and northwestern Mexico.

Revised Diagnosis: Derived characters that distinguish C. lepophagus from E. davisi are larger size and more robust skull and jaws; frontal sinus extends more posteriorly; sagittal crest stronger with contribution from frontal; inion narrower and sometimes pointed; m1 talonid with entoconid and hypoconid usually linked by transverse crest; hypoconulid shelf relatively larger but with distinct cusp rarely present; angular process of mandible more robust; and longer forelimb relative to hindlimb (radius/tibia ratio.80% but,90%).

Canis lepophagus shares the above derived features with C. ferox , but it differs in more consistent m1 hypoconid-entoconid union through cristids, and reduction of M1 parastyle.

C. lepophagus differs from many larger species of Canis in its primitively small size; small I3 relative to I1–I2; P4 protocone more anteriorly directed; p4 lacks a posterolingual shelf and is higher than paraconid of m1; m3 retains two trigonid cusps; less inflated frontal sinus; relatively wider frontal shield; and relatively wider braincase.

Primitive characters that distinguish C. lepophagus from C. latrans are: greater postorbital constriction; zygomatic process dorsoventrally deeper with broad scar for masseter muscle; smaller bulla with less laterally extended tubular auditory meatus; P4 protocone situated more anteriorly; m1 less elongate with trigonid shorter relative to length of talonid and weaker hypoconulid; m2 larger relative to m1, metaconid lower crowned, and anterolabial cingulum stronger; less elongate limbs especially forelimb, with radius/tibia ratio exceeding 80% but less than that of C. latrans , where ratio usually exceeds 90%.

Description and Comparison: Among the topotypic Cita Canyon collection of Canis lepophagus are two female and two male skulls. The type WTUC 881 (fig. 41A–C) and WTUC 760 (fig. 41D–F) are females by virtue of their small canines, the slenderness and elongation of their skulls, narrow muzzles, less expanded frontal shield, and weaker sagittal crests. Males are represented by the skulls of WTUC 722 and WTUC 2523 and a maxillary fragment, WTUC 558d, in which the diameter of the canine is 9.4 mm. The males seem to have proportionally larger bullae; particularly noticeable is the posterior expansion of the bullae. The lambdoidal crests are more laterally extended in the males, and in both sexes the inion extends posteriorly well beyond the condyles. In WTUC 760, a female skull (fig. 41D–F), the inion is unusually narrow and pointed, suggesting that the range in variation is comparable to that of other species of Canis . Temporal crests join anterior to the frontoparietal suture to form a strong continuous sagittal crest. The form of the zygoma conforms to the pattern seen in Canis and differs strongly from that of E. davisi in lacking the primitive flaring and eversion of the orbital part of the arch. The masseteric scar on the zygoma is strongly developed in both sexes, often terminating ventrally in a crest or knoblike process.

The premolars are large in this species and show considerable variation, with the males having the larger and more robust teeth. The P3 lacks a posterior cusp in most individuals although it may at times be present, as in the holotype, WTUC 881 (fig. 41C). Measurements reveal considerable variation in the P4 dimensions, and here again the males seem to have slightly larger and more robust teeth. In all cases the P4 narrows posteriorly so that the transverse diameter across the paracone is greater than across the metacone. The P4 protocone is anterolingually directed and usually forms the most anterior part of the tooth. The M1 has a well-developed continuous labial cingulum that is sometimes produced into a low parastyle. The paracone is larger and taller than the metacone, but the difference in size is not as extreme as in most species of Canis . A distinguishable paraconule and a strong metaconule are present. Considerable variation in the proportion of the length to width of the upper M1 seems to result, in part, from the variable development of the hypocone and the cingulum. In individuals where the M1 cingulum can be observed (WTUC 1531, 1038, 530, 56011-J) the lingual cingulum is continuous from the hypocone across the face of the protocone to the paracone, where it joins the labial cingulum. In most individuals the M1 appears transversely wide relatively to its length; however, in a few individuals (WTUC 530 and 560J) the M1 is markedly narrower, approaching the condition commonly observed in E. davisi . Compared with the size of M1, the M2 seems relatively large with a comparatively strong labial cingulum that is particularly well developed around the paracone. The paracone is slightly larger and taller than the metacone, and the conules are weakly developed. The hypocone is strong and continuous with the anterior cingulum, which extends across the face of the protocone, and may reach the anterolabial cingulum.

The horizontal ramus is relatively deep for its size and somewhat more robust, particularly anteriorly, in the males. Two mental foramina are present, with the anterior foramen the larger and lying consistently beneath the diastema between p1 and p2. The posterior mental foramen is small and its position varies between the anterior and posterior roots of p3. The masseteric fossa is deep with a well-marked anterior and ventral margin. The coronoid process tapers only slightly dorsally, and a posterior hook is frequently present. A strong angular process is conspicuously marked by muscular insertions, especially for the enlarged superior branch of the median pterygoid muscle. The process still terminates in a prominent dorsal hook. The form of the angular process closely resembles that of other species of Canis and contrasts markedly with the slender, foxlike process of E. davisi .

The lower premolars are relatively large, with the largest in the males. They vary from elongate and low-crowned (WTUC 559a, fig. 42A) to higher crowned (WTUC 560, fig. 42D–E). Individuals with the highest crowned premolars also have the most prominent posterior cusps on p3 and p4. None shows posterior cusps on p2. The p4 may show a small second posterior cusp lying immediately anterior to the cingulum in both the high- and low-crowned individuals (JWT 559A, WTUC 560, JWT 1027d, and JWT 558). The tip of the unworn crown of p4 consistently lies at or above the paraconid of m1 regardless of relative crown height. For the most part the tips of the premolars form a rising gradient front to back, with their crown bases lying at approximately the same level.

The lower carnassials have a wide talonid but show some variation in the obliqueness of the paraconid shear. The angle of the paraconid varies from that typical of the other Pleistocene and Recent canids to a more oblique shear present in WTUC 560 (fig. 42E). The anterior face of the paraconid is nearly vertical. A weak protostylid ridge is developed in at least one individual (WTUC 560d) and a weak anterolabial cingulum is sometimes developed. The hypoconid is larger than the entoconid and they are usually joined by a low transverse crest separating the talonid into anterior and posterior basins. A hypoconulid was seen in only one specimen (JWT 5601) but a hypoconulid shelf is usually present. The entoconid is situated slightly posterior to the hypoconid, and a small entoconulid may be present.

The m2 is widest anteriorly, with the talonid narrowing posteriorly. An anterolabial cingulum usually occurs but is not strongly developed. A paracristid is ordinarily present and may be produced into a cuspule forming the anterior part of the m2. This cuspule is removed shortly after wear begins. The protoconid and metaconid are subequal in height, with the metaconid slightly posterior to the protoconid. The hypoconid is present but a distinct entoconid is lacking, and the posterior and lingual part of the talonid is marked by a crest bearing low cuspules. The m3 is oval in shape with a distinct metaconid and protoconid, sometimes connected by a cristid, lying just posterior to the center of the tooth.

Discussion: In his description of Canis lepophagus, Johnston (1938: 385) observed that this taxon is slenderer in the general proportions of the skull and skeleton than in living C. latrans . He also noted that the sagittal and lambdoidal crests of C. lepophagus are stronger, and the braincase is not expanded. Giles (1960: 377) made a multivariate analysis of six mandibular rami of C. lepophagus from Cita Canyon. From this study he concluded that C. lepophagus ‘‘seems to rate only subspecific distinction within C. latrans .’’ Nowak (1979: 69) observed that the skulls of C. lepophagus averaged smaller than C. latrans , but overlapping occurred in most measured dimensions. Nowak also noted that the braincase was smaller and less inflated dorsoposteriorly, and he regarded this form as a species separate from C. latrans .

We have compared the measurements of four skulls of C. lepophagus from Cita Canyon with 12 skulls (6 male and 6 female) of C. latrans from Nevada in a log-ratio diagram (fig. 43). Based on this small sample, the only skull dimension of C. lepophagus that diverges sharply from those of C. latrans is the width of the frontal shield. It is relatively wider in C. lepophagus as noted by Nowak (1979). We also agree with Nowak that the braincase is narrower anteriorly.

Although C. lepophagus retains a number of primitive features in common with Eucyon davisi , it is an advanced canid and shares a number of derived features with larger species of Canis : posterior expansion of the frontal sinus; supraoccipital narrowed dorsally, sometimes reduced to a point at the inion; m1 talonid with transverse crest usually present between entoconid and hypoconid; angular process of the mandibular ramus robust and hooklike with a large scar for the superior ramus of the median pterygoid muscle; and the forelimbs assigned to C. lepophagus suggest that they were moderately elongate relative to hindlimbs with the radius/ tibia ratio greater than 80%, but shorter than in some other species of Canis , in which the radius/tibia ratio may exceed 90% (e.g., C. lupus and C. latrans ). However, C. lepophagus lacks several synapomorphies that C. latrans shares with C. lupus and is thus considerably removed from the close relationship implied by previous authors. Its lack of autapomorphies, however, suggests a stem (or ‘‘ancestral’’) position relative to the radiation of Canis crown group species.