Australodelphis

Australodelphis Temporal range: Pliocene (4.5 - 4.1 mya) PreЄ Є O S D C P T J K Pg N ↓
Artist's reconstruction
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Mammalia
Order:	Artiodactyla
Infraorder:	Cetacea
Family:	Delphinidae
Genus:	†Australodelphis
Species:	†A. mirus
Binomial name
Australodelphis mirus Fordyce et al., 2002

Australodelphis mirus is an extinct Pliocene dolphin.A. mirus is known from fossils found in the Sørsdal Formation, Mule Peninsula, Vestfold Hills, East Antarctica. The genus has been described as an example of convergent evolution with beaked whales.

The generic name Australodelphis is derived from the Latin australis meaning southern and delphis meaning dolphin, in reference to its discovery in Antarctica. The species name mirus is Latin for strange or wonderful, and was chosen to reflect the unexpected morphology of the type specimen. While not described until 2002, the type specimen of A. mirus was collected between 1985 and 1986, and a further four specimens were found between 1986 and 1994. Prior to the description of Australodelphis in 2002, the genus was mentioned briefly in several publications between 1988 and 1993. The holotype skull was figured in 1988 by R. E. Fordyce and Australodelphis mirus first appeared as a nomen nudum in E. H. Colbert's 1991 "Mesozoic and Cainozoic tetrapod fossils from Antarctica". A second species of Australodelphis was noted by R. E. Fordyce and G. Quilty in their 1993 publication on the stratigraphic context of the Marine Plain sediments, but this second species has yet to be formally described.

The type locality of the genus marks Australodelphis as the first Pliocene higher vertebrate to be named from Antarctica, and the first cetacean to be named from sediments dating after the final breakup of Gondwana. All known specimens of Australodelphis were recovered from sediments of the Sørsdal Formation which outcrops at Marine Plain about 8 km south of Davis Station in the Vestfold Hills of East Antarctica. The fossils are found in massive to poorly bedded muddy siltstone, dated at 4.5 to 4.1 million years old, placing the sediments in the Early Pliocene. The cetaceans of the Sørsdal Formation are found in association with the extinct diatom Fragilariopsis barronii and the scallop Chlamys tuftensis. Poor sorting and fine-grained sediments, combined with cetacean bones and diatom depositions, indicate the area was a sheltered, shallow, glaciomarine inner shelf.