Saturday, April 11, 2009

Cretaceous Multituberculata from Australia

Thomas H. Rich (et. al.), Curator of Vertebrate Paleontology at the Museum of Victoria in Melbourne, Australia, recently published a description of dentary fragments from a member of the Multituberculata in the Journal Acta Palaeolontologica Polonica.

Several mammalian families have previously been identified from the Aptian formation (where the current fossil was found), most of these are believed to represent species endemic to Australia; however one family – the Ornithorhynchidae – have also been found in Argentina. Ornithorhynchidae, a group of monotremes, have been used to provide evidence for mammalian dispersal between South America and Australia during the Mesozoic.

According to the authors, these prehistoric platypuses provide biogeographical clues because “[g]iven the relative geographic positions of Australia and South America during the Mesozoic, it is reasonable to expect that were it then possible to do so, at least one of these terrestrial mammals would have traversed the Antarctic landmasses, in one direction or the other…”

A dentary fragment containing a tiny left plagiaulacoid fourth lower premolar from the Early Cretaceous (Aptian) of Victoria provides the first evidence of the Multituberculata from Australia. This unique specimen represents a new genus and species, Corriebaatar marywaltersae, and is placed in a new family, Corriebaataridae. The Australian fossil, together with meagre records of multituberculates from South America, Africa, and Madagascar, reinforces the view that Multituberculata had a cosmopolitan distribution during the Mesozoic, with dispersal into eastern Gondwana probably occurring prior to enforcement of climatic barriers (indicated by marked differentiation in regional floras) in the Early Cretaceous.

Holotype of multituberculate mammal Corriebaatar marywaltersae gen. et sp. nov. from Flat Rocks, Wonthaggi Formation (Aptian), Australia (NMV P216655), a left dentary fragment with p4 and anterior root of m1 in labial (A), lingual (B), and occlusal (C) views. Artwork by P. Trusler.

THOMAS H. RICH,et al. (2009). An Australian multituberculate and its palaeobiogeographic implications Acta Palaeolontologica Polonica
The article is available as a PDF HERE.

Beck, R., Godthelp, H., Weisbecker, V., Archer, M., & Hand, S. (2008). Australia's Oldest Marsupial Fossils and their Biogeographical Implications PLoS ONE, 3 (3) DOI: 10.1371/journal.pone.0001858

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