The First Record of the Plio-Pleistocene Hypercarnivorous Canid, Canis (Xenocyon) falconeri (Mammalia; Carnivora), from the Tama River, Akishima City, Western Tokyo, Japan

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Skeletal material of a large-sized canid, Canis (Xenocyon) falconeri, was excavated from the mud sediments of the upper part of the Kasumi Formation (Plio-Pleistocene). The age of the second Horinouchi ash bed above the fossil bed is estimated as 1.6Ma. I estimate the age of this fossil at about 1.8Ma.Although the skeletal elements were greatly disarticulated, it was possible to identify them as belonging to a single individual. The molar size of this canid is comparable with the extant northern races of Canis lupus. The carnassials have moderately hypercarnivorous characters in that the hypocone of the upper first molar is smaller than the protocone and is placed distally, and the entoconid of the lower first molar is very small but distinct. This Canid's upper fourth premolar is brachydont and the protocone relatively small. The lower third molar is present.This is the first record of a fossil canid from the Japanese Plio-Pleistocene and is worth examining in Japanese Plio-Pleistocene vertebrate fauna.