Cave canem! The earliest Canis (Xenocyon) (Canidae, Mammalia) of Europe: Taxonomic affinities and paleoecology of the fossil wild dogs

Unlike their medium-sized relatives of the genus Canis, whose arrival is dated around 3 Ma, the appearance in western Europe of large-sized hypercarnivorous canids took place at the beginning of the late Villafranchian (ca 2 Ma). Here, we report the earliest occurrence in this part of Eurasia of a Canis (Xenocyon) from the French site of Roca-Neya (Perrier area, recently dated to 2.6 Ma). Although represented only by mandibular specimens, the morphological and morphometric features resemble those of Canis (Xenocyon) falconeri (Forsyth Major, 1877), a large-sized canid with clear dentognathic adaptations to hypercarnivory, yet less developed compared to other later forms of this group. In our analysis, we revised the features of the subgenus Xenocyon and the present knowledge about these enigmatic forms. Following several studies, we performed analyses with the aim of providing the first estimate of the dietary preferences of Canis (Xenocyon) using selected morphometric ratios. The hypercarnivorous diet of this group was supported, while also the results indicate peculiar dentognathic proportions possessed by these fossil canids that differ from modern ones. The stoutness and development of some characteristics in the sample from Roca-Neyra (e.g., the depth of the mandible, the arched lower toothrow, the sturdy teeth) suggest high regimes of stresses in the mandible related to its predatory behavior.