Strangers in a strange land: Ecological dissimilarity to metatherian carnivores may partly explain early colonization of South America by Cyonasua-group procyonids

It was once thought that the endemic carnivorous mammals of South America, the metatherian sparassodonts, were driven extinct by North American carnivores through competitive exclusion. However, sparassodonts went extinct before most groups of carnivorans entered South America; only the endemic Cyonasua-group procyonids (Cyonasua and Chapalmalania), which immigrated to South America nearly four million years earlier than other carnivorans, significantly overlapped with sparassodonts in time. In this study, we examine the functional morphology of the dentition of Cyonasua and Chapalmalania through quantitative analysis to determine the dietary habits of these taxa and the degree to which they may have ecologically overlapped sparassodonts and large predatory Neogene didelphimorphians. We find Cyonasua and Chapalmalania to be more carnivorous than extant procyonids other than Bassariscus, in agreement with previous studies, but more omnivorous than most other carnivorans and all meat-eati...