First records of teratorns (Aves, Teratornithidae) in the Pleistocene of South America

CENIZO, MARCOS; TASSARA, DANIEL; NORIEGA, JORGE; TOMASSINI, RODRIGO

Diamante (Entre Ríos)

Encuentro; 9th International Meeting, Society of Avian Paleontology and Evolution; 2016

Society of Avian Paleontology and Evolution

We report here the first remains of teratorns found in the Pleistocene of South America.The recovered specimens come from two localities on the Atlantic coast of the Buenos Aires Province (Argentina) and they were exhumed in outcrops referred to Bonaerean Stage (Middle-Late Pleistocene).They are represented by an incomplete synsacrum found in the Playa del Barco locality; and associated fragments from the vicinity of Arroyo Chocorí locality, corresponding to a proximal end of right ulna, a portion of ulnar shaft and the right side of a manubrium sterni. Although the recovered remains are extremely fragmentary, they clearly differ from comparable bones of Cathartiformes and agree with Teratornis in the following combination of characters: (1) synsacrum in ventral view, corpus vertebrae wider and stouter, not progressively expanded cranioventrally and lacking ventral processes; (2) ulna in proximal view, cotyla dorsalis dorsally higher, (3) conspicuous tuberculum lig. collateralis ventralis; (4) ulna in dorsal view, impression m. scapulotricipitalis single, larger, deeper, and quadrangular shaped; (5) ulna in cranial view, incisura radialis very distinct, sharp-edged depression, highly pneumatic distally, and (6) impression brachialis wider, well-marked, more proximally extended and lacking pneumaticity; (7) sternum in cranioventral view, sternocoracoidal impression lacking foramen pneumaticum, and (8) well developed tubercula labri externus et internus. The proportions of all specimens are included within the observed range-size for Teratornis merriami, being larger than all known Cathartiformes. The presence of a possible teratorn among the bird taxa of the Late Pleistocene avifauna of La Carolina (Ecuador) had been previously suggested. However, the taxonomic identity of this specimen has not yet been reviewed and the material was never figured. In this way, the new records reported here allow to add a new member, and the largest, to the diversified guild of large carrion birds that proliferated during the South American Pleistocene.