Taxonomic status of Apterodytes ictus AMEGHINO, 1901 (Aves; Sphenisciformes) from the Early Miocene of Patagonia, Argentina

A proximal end of a humerus collected by C. AMEGHINO was designated as the holotype of Apterodytes ictus AMEGHINO, 1901 in the monotypic genus Apterodytes AMEGHINO, 1901. Later, AMEGHINO (1905) transferred this species to the new genus Palaeoupterodytes AMEGHINO, 1905. The validity and affinity of this species has been discussed controversial, not only on account of the poor preservation of the material, but also because of the characters used in its diagnosis and description. A systematic revision of Aptenodytes ictus (AMEGHINO, 1901) is presented. This is a proximal end of a right humerus strongly weathered that was interpreted as a complete humerus with an unique morphology. The characters included in the original diagnosis and the description are inadequate to compare with those of other species as they are based mainly on the assumption of the atrophy of a humerus that is in fact fractured and incomplete. Its morphology allows its confidant assignment to the family Spheniscidae, although it is not well enough preserved to assign it to any known genus. Therefore, this fossil is not appropriate to found a species on and Palaeoapterodytes ictus (AMEGHINO, 1901) must be considered as a nomen dubium.