Palaeospheniscus gracilis

This species was long believed to have first been found in Early Oligocene deposits. However, it seems that the type specimen, a tarsometatarsus, was recovered not from Early Oligocene rocks, but was found on top of them, having been displaced there from a later stratum. The location where the bone was found seems to have been near Cabeza Blanca. At any rate, all later specimens were found in the Early Miocene Gaiman Formation; those that have locality data are from the area around Trelew and Gaiman in Chubut Province, Argentina.^[1]

Some recent researchers^{[citation needed]} have suggested that this species should be considered a synonym of Palaeospheniscus bergi.

• Ameghino, Florentino (1899): [Description of Palaeospheniscus gracilis]. In: Sinopsis geologico-paleontologica (Segundo censo de la República Argentina). Suplemento.: 9. La Plata: La Libertad.
• Simpson, George Gaylord (1946): Fossil penguins. Bull. Am. Mus. Nat. Hist. 87: 7-99. PDF fulltext
• Simpson, George Gaylord (1971): Conspectus of Patagonian fossil penguins. American Museum Novitates 2488: 1-37. PDF fulltext