A new phorusrhacid (Aves: Cariamae) from the middle Miocene of Patagonia, Argentina

The anatomy of a new, enormous phorusrhacid (Aves: Cariamae) from the Middle Miocene Collon Curd Formation of northwestern Patagonia (Rio Negro province, Argentina) is described. The new phorusrhacid is known by a single specimen that consists of a nearly complete skull associated with a tarsometatarsus and a pedal phalanx. The new fossil is the largest known phorusrhacid and its morphology resembles more that of taxa traditionally grouped within phorusrhacines. Its skull-by far the best preserved among large phorusrhacids-provides a great deal of previously unknown anatomical information and indicates that reconstructions of the skull of gigantic phorusrhacids based on their smaller relatives are unwarranted.