Evolution and historical biogeography

Abstract

Abstract The origin and phylogeny of the Carnivora is inferred from fossils, their geological contexts, and genetic data. Modern estimates of divergence times of lineages employ both kinds of evidence. While the earliest eutherians pre-date the Cretaceous–Paleogene boundary, the major eutherian radiation followed the bolide impact on the coast of Yucatan around 66 million years ago. The immediate fossil ancestor of the earliest carnivoran is now uncertain; the most closely related lineage to the Carnivora is Pholidota, the pangolins. Carnivorans arose in North America, and all family-level diversification occurred in North America and Eurasia. Suborder Caniformia underwent its earliest radiations in North America; Feliformia did so in Eurasia. The Paleocene–Eocene Thermal Maximum may have been the impetus for the radiations of Carnivorans and other mammalian lineages. Subsequent dispersals of carnivorans between continents depended on episodic land bridges resulting from continent drift and sea level fluctuations. The bridge between North and South America caused highly asymmetrical exchanges of carnivorous eutherian lineages; lineages from South America made few and brief colonizations in Central America, whereas North American lineages colonized southward very successfully, displacing the dominant carnivorous forms. The morphological disparity of carnivorans varies strongly across families. Considering only the skull, the lowest disparity is found in the Felidae, and the highest in the Eupleridae. Post-cranial morphology varies strongly across the Mustelidae, but only little across the Canidae. Competition was a strong structuring force in paleocommunities of Carnivorans as it is in modern ones.