Evolution of size, diet and skull shape in South American canids (Carnivora, Canidae)

FRANCISCO J. PREVOSTI; ERIKA HINGST-ZAHER

Gramado

Congreso; VII Congresso Brasileiro de Mastozoologia; 2014

South America has a rich fauna of placental carnivores, that includes felids, mustelids, canids, mephitids and one ursid. Canids are very diversed in South America in the present with 10 species that represent two clades, the "South American clade" with five genera (Lycalopex, Atelocynus, Cerdocyon, Chrysocyon, Speothos) and nine species and Urocyon cinereoargenteus that represent a clade of "vulpines" mainly restricted to North America. This diversity is comprised mainly by generalist and omnivore species, with small body masses (mainly < 10 kg), except for Chrysocyon that is a large (> 20 kg) omnivore with long legs, and Speothos that is a small hypercanivore. But in the past there were several genera of the South American clade (e.g., Theriodictis, Protocyon) and the North American immigrant Canis dirus with large body masses and carnivore habits. In this contribution we explore the relationship between skull shape and diet habits in living canids to infer diet of the South America fossil canids using 2D geometric morphometrics and multivariate statistic methods. Body size of fossils were estimated with the centroid size and least square regressions. Finally, we explore the evolution of size, shape and diet optimizing this features in the phylogeny of this group. Our results showed that is a clear relationship between skull shape and diet. The extinct Canis dirus, Theriodictis and Protocyon had hypercarnivore diets and body masses above 20 kg. Hypercarnivore habits, and large sizes, evolved convergently in the "Canis clade" and in the "South American clade". This ecomorph is represented in the last clade is by the monophyletic group of Theriodictis + Protocyon + Speothos.