Lead author Ana Valenzuela-Toro holds an incomplete right femur of the paratype specimen (USNM 438712) belonging to the new fossil seal named Australophoca changorum. (Photo: NMNH Imaging / Smithsonian Institution)
Today, my South American colleagues and I announce the publication of a new species of fossil seal from the western coast of South America. The name of the new genus and species, Australophoca changorum, reflects its austral origin from Chile and Peru, and honors the Changos, a coastal tribe of indigenous people who lived in the Atacama (from northern Chile to southern Peru), and were short in stature. The description, published in Papers in Palaeontology, provides a scientific name for a dwarf species of true seal from the late Miocene Bahía Inglesa and Pisco formations of Chile and Peru, respectively. One of the paratype specimens that we identified was originally recovered from Cerro Ballena in the Atacama Region of Chile; the type specimen is USNM 438707.
This tiny fossil seal was smaller than a living harbor seal (Phoca vitulina), and ranks among the smallest true seals ever described, including both living and fossil ones. Interestingly, in the past ~11-3 million years, the western coast of South America seems to have been only occupied by true seals (or phocids), a fact that stands in stark difference to what we know about pinniped communities from other parts of the world, and other time in the geologic record. This unusual feature of the pinniped community in western South America fits into a broader pattern of ecological turnover seen in the fossil record of marine consumers, including pinnipeds and seabirds, throughout the Southern Hemisphere, since the late Miocene.
Figure 6, from Valenzuela-Toro et al. (2015) shows the relative size of Australophoca changorum (number 14 in the figure) to other assemblages of fossil and living pinnipeds, from other places (based on latitude) and geologic times.