Palaeeudyptes

Abstract: Two collections of fossil penguins have been made from Seymour Island, off the north-eastern end of the Antarctic Peninsula, one by a Swedish expedition in 1901-1903 and the other by a British expedition in 1946. The age has usually been considered early Miocene but is probably earlier, late Eocene now seeming most likely but still uncertain. Wiman in 1905 based six then new generic and specific names on the Swedish collection. Anthropornis nordenskjoeldii and Delphinornis larsenii are considered valid. Pachypteryx grandis is a valid species but is transferred to Anthropornis. Eosphaeniscus gunnari is a valid species transferred to Palaeeudyptes, a genus otherwise known from New Zealand and Australia. Orthopteryx gigas and Ichtyopteryx gracilis are considered essentially indeterminate, as are two groups of bones not named by Wiman. Marples named genus and species Notodyptes wimani from the British collection. The species is accepted but transferred to the New Zealand genus Archaeospheniscus. Wimanornis seymourensis, new genus and species, is based on a British specimen. This penguin fauna is essentially similar to the early (late Eocene and early Oligocene) faunas known from New Zealand. In the probable absence of species in common, geographic proximity is not indicated. The ecological similarity and some indirect evidence suggest that despite the presence of relative gigantism these penguins lived in considerably warmer waters than those of the present Antarctic coast.

Abstract: Penguin bones from the Eocene La Meseta Formation (Seymour Island, Antarctic Peninsula) constitute the only extensive fossil record of Antarctic Sphenisciformes. Here, we synonymize some of the recognized genera (Anthropornis with Orthopteryx, Delphinornis with Ichtyopteryx) and species (Anthropornis nordenskjoeldi with Orthopteryx gigas, Delphinornis gracilis with Ichtyopteryx gracilis). Moreover, we suggest that Antarctic species of Anthropornis and Palaeeudyptes, so-called giant penguins, may in fact comprise only one species each instead of two, based on evidence of well-marked sexual dimorphism. We also present new estimates of body mass based on femora testifying to the impressive scope of interspecific body-size variation in Eocene Antarctic penguins.

Abstract: This study presents the first record of Eocene birds from the western margin of southernmost South America. Three localities in Magallanes, southern Chile, have yielded a total of eleven bird remains, including Sphenisciformes (penguins) and one record tentatively assigned to cf. Ardeidae (egrets). Two different groups of penguins have been recognized from these localities. The first group is similar in size to the smallest taxa previously described from Seymour Island, Marambiornis Myrcha et al., 2002, Mesetaornis Myrcha et al., 2002, and Delphinornis Wiman, 1905. The second recognized group is similar in size to the biggest taxa from Seymour Island; based on the available remains, we recognize the genus Palaeeudyptes Huxley, 1859, one of the most widespread penguin genera in the Southern Hemisphere during the Eocene. The stratigraphic context of the localities indicates a certain level of correlation with the geological units described on Seymour Island. The newly studied materials cast more light on the paleobiogeography of the group, extending the known ranges to the South American continent. In addition to the newly discovered birds, the presence of several taxa of elasmobranchs previously recovered exclusively from Eocene beds in the Southern Hemisphere help to clarify the age of the studied localities, widely discussed during the last decades. This paper verifies the presence of extensive Eocene sedimentary successions with fossil vertebrates along the western margin of southern South America, contrary to the previous assumption that such a record is lacking in Chile.