The carnivoran fauna of Rancho La Brea: Average or aberrant?

Abstract

The late Pleistocene asphalt seeps of Rancho La Brea are well-known for their impressive assemblage of carnivorans, which make up the vast majority of the preserved fauna. Of particular interest is the large number of dire wolf and sabertooth cat specimens. Carcass domination, the hypothesis that predators engaged in intense competition for trapped prey, may explain the mechanism of this predator trap. Large and social animals would have fared best during competition over carcasses, so the preponderance of Canis dirus and Smilodon fatalis has been seen as evidence of their sociality. However, no studies have quantitatively determined whether the relative carnivoran species abundances in Rancho La Brea differ significantly from those in California or North America at large. We compare numbers of identified specimens (NISP) from the Rancho La Brea fauna to regional and continental faunal data compiled from the FAUNMAP II database to test this hypothesis. Our results confirm that the carnivoran fauna in Rancho La Brea is unique, with preservation patterns generally supporting the carcass domination hypothesis as well as the sociality of S. fatalis.