查看文章

Modern penguins are typically small to medium-sized birds, and nearly all known modern specimens are smaller than the most archaic Paleogene relatives. Here we report an incomplete humerus, associated femur and tibiatarsus of a new spheniscid, Crossvallia unienwillia nov. gen. and sp., from the Late Paleocene (~55 million years, Myr) of Antarctica, extending the record of spheniscids by about 15 Myr. Its large size (length ~140 cm) supports the idea that large body size in penguins was acquired independently at different times (Late Paleocene and Late Eocene) under dramatically different environmental conditions. Comparison of its osteological anatomy suggests that the new taxon is closely related to the extinct Anthropornithinae rather than to other penguin lineages.