EVOLUTIONARY PATTERNS IN PLEISTOCENE TO RECENT CALIFORNIA CONDORS

Pleistocene fossils related to the living California condor (Gymnogyps californianus) were originally assigned to the species G. amplus, but more recently considered a subspecies of G. californianus. To resolve this dispute, we evaluated the differences between the living condors and their extinct relatives, and examine their evolutionary patterns. The limb bones (using seven variables on each element) and skulls (using 13 variables) of G. amplus specimens from the Pleistocene of Rancho La Brea and modern G. californianus (about 40 specimens of each species) were quantitatively compared using both bivariate and multivariate techniques. Although the two species did not separate on the basis of distal limb bone measurements, proximal limb elements and skulls showed patterns of variation consistent with two different species. Based on these results, we support the validity of the name G. amplus as a distinct species from G. californianus, rather than a chronological subspecies. In addition, there is no significant size or shape change through time in samples ranging from 35,000 radiocarbon years b.p. to the early Holocene (9000 radiocarbon years b.p.), suggesting evolutionary stasis in the face of the climatic changes of the last glacial-interglacial cycle. Interestingly, specimens from an archeological site in Oregon suggest that G. amplus survived into the period of human habitation, and may have coexisted with the smaller G. californianus.