Antarctic Science



Earth Sciences

Australodelphis mirus, a bizarre new toothless ziphiid-like fossil dolphin (Cetacea: Delphinidae) from the Pliocene of Vestfold Hills, East Antarctica


R. Ewan Fordyce a1, Patrick G. Quilty a2 and James Daniels a1p1
a1 Department of Geology, University of Otago, PO Box 56, Dunedin, New Zealand
a2 Antarctic Division, Channel Highway, Kingston, TAS 7050, Australia

Article author query
fordyce r   [PubMed][Google Scholar] 
quilty p   [PubMed][Google Scholar] 
daniels j   [PubMed][Google Scholar] 

Abstract

Australodelphis mirus (Delphinidae n. gen., n. sp) is a small extinct Early Pliocene dolphin known from five individuals from shallow-water strata of the Sørsdal Formation, Vestfold Hills, East Antarctica. Australodelphis mirus is the first higher vertebrate named from the Oligocene-Pleistocene interval on land in Antarctica, and is the first cetacean fossil from the polar margin of circum-Antarctic Southern Ocean that postdates the break-up of Gondwana. The dolphin is convergent in skull form with some living beaked whales (Mesoplodon spp.; Family Ziphiidae) in its long, narrow and toothless upper jaw and face, but skull suture patterns, basicranial sinuses, and ear-bones indicate close relationship with living long-beaked dolphins (Delphinidae). Australodelphis mirus perhaps was a suction-feeding squid-eater which occupied quiet near-shore shelf waters influenced by glaciers but probably lacking major sea-ice. Possible ecological equivalents of A. mirus (small ziphiids, long-beaked dolphins) do not occupy Antarctic waters today, perhaps excluded by cold conditions and/or sea-ice cover. Earlier Pliocene cetaceans worldwide reveal significant extinct and sometimes bizarre taxa, and extant families with ranges quite different from today, pointing to climate-related changes in cetacean ecology in the last 2–3 million years.

(Received May 25 2000)
(Accepted September 17 2001)


Key Words: Antarctic; climate; dolphin; ecology; evolution.

Correspondence:
p1 School of Earth Sciences, University of Melbourne, Parkville, VIC 3010, Australia


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