A revision of the only Palaeocene penguin from Antarctica with remarks on early evolution of Sphenisciformes

JADWISZCZAK, P.; ACOSTA HOSPITALECHE, C .; REGUERO, M.

AMEGHINIANA

ASOCIACION PALEONTOLOGICA ARGENTINA

Lugar: Buenos Aires; Año: 2013 vol. 50 p. 545 - 553

0002-7014

Redescribed and reinterpreted here is a partial skeleton of the oldest Antarctic penguin, Crossvallia unienwillia from the late Paleocene of Marambio (Seymour) Island. A thorough morphological analysis of limb bones (humerus, femur and tibiotarsus) allowed us to report both an amended reconstruction of type specimens and a revised taxonomic diagnosis of this large-sized early penguin. Moreover, an additional skeletal element, a single thoracic vertebra, is described for the first time. C. unienwillia is characterized by a mixture of features typical of both geologically older and younger penguins, supplemented by characters that are obviously unique. The above-mentioned findings shed new light on the very beginning of penguin evolution.