A partial skeleton of a new fossil loon (Aves, Gaviiformes) from the early Oligocene of Germany with preserved stomach content

A partial skeleton of a new fossil loon (Aves, Gaviiformes), ?Colymboides metzleri n.sp., is described from the early Oligocene (Rupelian) of Frauenweiler in Germany. The new species resembles the early Miocene species Colymboides minutus in size and overall morphology, but differs in several osteological details. The specimen represents the first associated remains of an early Tertiary loon. Preserved stomach content further provides the first direct evidence that early Tertiary loons were already specialized towards a piscivorous diet, hunting fishes in a marine environment.Communicated by F. Bairlein