Preliminary observations on the paleobiology and evolution of teratorns (Aves: Teratornithidae)

Abstract

An analysis of the functional morphology of the skull of Teratomis merriami indicates that these giant flying birds were predaceous carnivores. This contrasts with prior assumptions that teratorns were scavengers like vultures. The large wingspans of teratorns limited them to savanna habitats. Teratorns probably originated in South America, sharing the dominance of the carnivore adaptive zone in the Tertiary of South America with the better known cursorial carnivorous birds collectively referred to as phorusrhacoids. Their evolution to such large flying birds was most likely directly tied to the progressive development of widespread savanna habitat in South America during the Tertiary. The soaring manner of flight of teratorns may have prevented their dispersal into North America until after the closure of the Central American land bridge. Expansion of savanna habitats in the Americas during Pleistocene glacial periods probably aided this dispersal.