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Ceratosaurian astragalocalcaneum from Australia

From: Ben Creisler

A new online paper:

Erich M. G. Fitzgerald, Matthew T. Carrano, Timothy Holland, Barbara
E. Wagstaff, David Pickering, Thomas H. Rich and Patricia Vickers-Rich
First ceratosaurian dinosaur from Australia.
Naturwissenschaften (advance online publication)
DOI: 10.1007/s00114-012-0915-3

The basal theropod dinosaur clade Ceratosauria, and its subclade
Abelisauroidea, is characteristic of late Mesozoic terrestrial
vertebrate faunas in western Gondwana (South America, Africa,
Madagascar, and India) and Europe. Yet unambiguous records of
ceratosaurs have hitherto been absent from Australia, where the
theropod assemblage appears to include several typically Laurasian
clades. Here, we report the first evidence of ceratosaurs (and
potentially abelisauroids) from eastern Gondwana––a diagnostic
astragalocalcaneum from the Aptian (121–125 Ma) of Victoria,
Australia. Ceratosauria thus occurred in both western and eastern
Gondwana during the Early Cretaceous. This fossil adds to the poorly
known dinosaur fauna of Australia, a major clade of basal theropods,
emphasising that its mid-Cretaceous theropod diversity was
surprisingly cosmopolitan despite relative geographic isolation,
including clades that have been thought to be typical of both Gondwana
and Laurasia––Ceratosauria, Spinosauridae, Carcharodontosauria,
Tyrannosauroidea, and Deinonychosauria. Such a contemporaneous
association of theropod clades is unknown from other Gondwanan
continents and questions the views that the late Mesozoic dinosaur
fauna of Australia was dominated by Gondwanan or Laurasian elements,
extreme isolation, relictualism, and/or novelty as a ‘centre of
origin’. The cosmopolitan theropod fauna of Australia probably
reflects the global distribution of these clades early in their
history, prior to significant continental breakup.