Eocene birds from the western margin of southernmost South America

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.

A Late Eocene age proposal for the Loreto Formation (Brunswick Peninsula, southernmost Chile), based on fossil cartilaginous fishes, paleobotany and radiometric evidence

“…K. 6 m of massive sandstones with some concretionary beds. This unit also includes fine conglomerate lenses and abundant teeth of cartilaginous fishes, with less frequent bird bone fragments (Sallaberry et al, 2010). L. 6 m of medium-grained, grey sandstones, with very fine coal intercalations.…”

“…Two bone fragments of fossil penguins were recovered from the Loreto Formation and described by Sallaberry et al (2010). The material includes an ungual phalanx (SGO.PV.6652) and a tarsometarsal fragment (SGO.PV.6653), but the fragmentary condition of these remains does not allow them to be identified to genus or species level.…”

First bird remains from the Eocene of Algarrobo, central Chile

“…Their systematic position has been revised by Acosta Hospitaleche (2005) confirming their stem position. Southern discoveries also include indeterminate penguin remains (Sphenisciformes), represented at least by two morphotypes of different size, also large-sized penguins of the genus Palaeeudyptes, and a fragmentary tibiotarsus referred to a probable indeterminate Ardeidae, all recovered from three units of middle to late Eocene exposed in Magallanes, southernmost Chile (Sallaberry et al, 2010). The low-latitude records are represented by endemic species such as Perudyptes devriesi Clarke et al, 2007, from middle Eocene levels of the Paracas Formation, Peru, and Icadyptes salasi Clarke et al, 2007, recovered (Jadwiszczak, 2011).…”

Short Note: New data on morphology of late Eocene penguins and implications for their geographic distribution

“…The record of Eocene penguins from South America comprises a partial skeleton (slightly smaller than that of A. forsteri) from the late middle Eocene of Argentine Tierra del Fuego (Clarke et al 2003), ten bones of both small-bodied and 'giant' birds (undetermined sphenisciforms and Palaeeudyptes sp. respectively) from the middle to late Eocene of the Magallanes Region, Chile (Sallaberry et al 2010), and partial skeletons of three species from the middle and late Eocene of Peru: a relatively largebodied Perudyptes devriesi Clarke et al, 2007 as well as two 'giant' penguins, Icadyptes salasi Clarke et al, 2007 and Inkayacu paracasensis Clarke et al, 2010(Clarke et al 2007, 2010. Inkayacu paracasensis, diagnosed mainly on the basis of five ''autapomorphies within Sphenisciformes'' (i.e.…”