Cerdocyon Smith, 1839

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 : 78-79

Cerdocyon Smith, 1839

Carcinocyon J. A. Allen, 1905 .

Type Species: Cerdocyon thous (Linnaeus), 1766 .

Included Species: C. texanus , new species, and Cerdocyon ? avius Torres and Ferrusquía, 1981 .

Distribution: Tropical South America (see Langguth, 1969: fig. 1 for map) for C. thous and closely allied late Pleistocene forms,

earliest Pliocene of New Mexico and Texas for C. texanus , and early Pliocene of Baja California Sur for C.? avius .

Revised Diagnosis: As indicated by Tedford et al. (1995), the synapomorphy that unites Cerdocyon with Atelocynus and Speothos and distinguishes it from more plesiomorphic South American Canini ( Dusicyon , Pseudalopex , and Lycalopex ) is the further expansion of the angular process of the mandible and enlargement of the fossa for the inferior ramus of the median pterygoid muscle. Additionally, other synapomorphies specifically unite Cerdocyon and its sister taxon Nyctereutes such as presence of a subangular lobe of the mandible and short and recurved canines of small diameter. Cerdocyon differs from most cerdocyonines in that its palate does not extend behind the toothrow. The same is true for fossil species of Nyctereutes , but in the living N. procyonoides the palate is long.

Discussion: Cerdocyon texanus , and to a lesser extent C.? avius ( Torres and Ferrusquía, 1981) , possesses derived dental and mandibular features that are unlike any other members of the North American Canina but are shared with Cerdocyon and, in some instances, other South American canids and Eurasian Nyctereutes . The North American fossil taxa referred to Cerdocyon are morphologically similar to C. thous in that they share the following derived characters: canines short and strongly curved backward; m1 and m2 with mesoconid on crista obliqua (in C. texanus ); upper first molar broad and large relative to the size of the upper carnassial with strongly developed conules; rounded subangular region and deep angular process. All of these characters are shared with Nyctereutes , except that the subangular lobe is more similar to certain Eurasian early Pliocene species attributed to Nyctereutes ( N. donnezani and N. tingi ). Later species of Nyctereutes have a more highly developed subangular lobe.