Systematics of Pliocene dolphins (Odontoceti Delphinidae) from Marine Plain, Antarctica

Daniels, Jim (James), 1971-

This thesis describes Australodelphis mirus and Australodelphis new species ... L'"'"'u··. Delphinidae, new genus, new species), two species of dolphin from the Early glaciomarine S0rsdal formation, Marine Plain in the Vestfold Hills, East Antarctica. two extinct species are Early Pliocene in age and are known from skulls, tympanaand postcranial elements from seven individuals. The fossils represent the only higher vertebrate fossils from the Antarctic Late Oligocene to Pleistocene interval. dolphin species have bone contact relationships similar to those of extant delphinids; , both species have a remarkably convergent cranial topography with extant toothless whales in the family Ziphiidae (Cetacea: Odontoceti). In particular, Australodelphis appears dramatically convergent with beaked whales in the genus Mesoplodon : Ziphiidae). These similarities suggest that Australodelphis mirus perhaps had u.u·-..->.U'Io.V habits (echolocating, suction-feeding, and possibly teuthophagy). Australodelphis and Australodelphis new species appear to be related to extant longirostral delphinids ... ~~--'""·" .... ~"': Delphininae ), although both species appear too derived to be ancestral to any Other fragmentary specimens from Marine Plain represent a species of small right (Mysticeti: Balaenidae: genus and species uncertain). These cetacean fossils from Marine Plain are unique in that small dolphins, small and small right whales do not appear to be ecologically important in the modem · waters. Elsewhere, Early Pliocene and Late Miocene cetacean assemblages are different from Late Pliocene - Recent assemblages, pointing to as-yet poorly understood """u~~~;:-, in cetacean ecology in about the middle of the Pliocene.

400 p. : ill. (some col.), maps (some col.) ; 30 cm.

1996Daniels