The endemic insular canid Cynotherium sardous is known for one and a half century, yet its phylogenetic position remained unsolved. This was because inherited ancestral characters and acquired adaptations to different ecological pressures could not be separated. Morphological and biometrical data alone are therefore insufficient. In this study the problem is approached again, with the use of morphological features that were either overlooked or could not be explained properly, in combination with results from recent major revisions of canid phylogeny. It appears that Xenocyon is the most parsimonious ancestor of Cynotherium, and that this large hypercarnivorous canid, once on the island, faced a rather different menu consisting of small prey only. The subsequent necessary adaptation resulted in a small-sized dog which carried its head much in the way foxes do and was able to hold its body low to the ground and move its head laterally better than any living canid. Its dentition and brain morphology remained much the same, whereas its skull lost the typical fortifications seen in the other hypercarnivorous canids; these are considered superfluous for Cynotherium who had to exchange big and strong prey for small and fast prey.
Read the full text in LYRAS G.A., VAN DER GEER A.A.E., DERMITZAKIS M.D., DE VOS J. (2006). Cynotherium sardous, an insular canid (Mammalia: Carnivora) from the Pleistocene of Sardinia, and its origin. Journal of Vertebrate Paleontology 26(3): 735-745,
and in LYRAS G.A., VAN DER GEER A.A.E. (2006). Adaptations of the Pleistocene island canid Cynotherium sardous (Sardinia, Italy) for hunting small prey. Cranium 23 (1): 51-60 (for pdf, click http://users.uoa.gr/~geeraae/publications/2006-Cranium-Cynotherium.pdf )
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