First Known Cranium of Cuvieronius (Proboscidea: Gomphotheriidae) from North America

We describe the first known complete cranium of an adult Cuvieronius from North America, dated to approximately 1.2 Ma, Early Irvingtonian North American Land Mammal Age. It differs in some details from better-known later Andean populations of Cuvieronius that may reflect polymorphism, sexual dimorphism, ontogeny, genetic divergence, or erroneously reconstructed specimens. We argue that North/Central American and South American Cuvieronius are most logically two genetically distinct cryptic species based on differences in their ages and our inferences about genetic divergence arising from an initial founder effect and/or isolation by distance, followed by allopatry over a long geologic time interval.