C Ontributions in S Cience

Abstract

An extensive study of the comparative osteology of turkeys (Aves: Meleagrididae) confirms the validity of the extinct California Turkey, Meleagris californica. The study included all major and many minor skeletal elements of adult specimens of M. californica, best known from the asphalt deposits at Rancho La Brea, California, and both species of extant turkeys: Meleagris gallopavo and Meleagris ocellata. The study also confirmed that M. californica is more closely related to M. gallopavo than to M. ocellata. A review of turkey remains from localities other than Rancho La Brea confirmed the presence of M. californica in California within a relatively small geographic range extending from Orange County in the south, through Los Angeles County, to Santa Barbara County in the north. Other, unconfirmed records of fossil turkeys in the western United States suggest that the species might have been more widespread. Based on a unique combination of characters, we confirmed the presence of Meleagris crassipes in Howells Ridge Cave, Grant County, New Mexico, which indicates that the geographic range of this extinct species extended from northeastern Mexico (San Josecito Cave) to at least New Mexico in the late Pleistocene. The close osteological similarity between M. californica and M. gallopavo suggests that the ancestors of M. californica became isolated in California only after nearing the M. gallopavo grade, but certain osteological features suggest different adaptations in the two species following divergence of their respective lineages. The high incidence of entrapment in the La Brea asphalt seeps is linked to the species social behavior. The end Pleistocene extinction of M. californica might have resulted from the coincidental occurrence of two factors: a dramatic drop of precipitation to well below modern precipitation levels beginning about 11,500 BP, which would have concentrated local populations of turkeys around limited roost sites and water supplies, and the arrival of paleoindians in California, who might have hunted the concentrated birds to extinction.