Multiple hypotheses about two mammalian upper dentitions from the Early Cretaceous of Australia

Abstract

Two enigmatic, poorly preserved specimens of mammalian upper molars have been recovered from the Eric the Red West locality in Victoria, Australia. They are two of the three known specimens of mammalian upper molars from the Mesozoic of Australia. The two are quite different from one another. One is likely to be a tribosphenic mammal, the other may have a distant relationship to the monotreme or haramyid Kollikodon.

Thomas H. Rich [[email protected]], Timothy Ziegler [[email protected]], Peter Trusler [[email protected]], Timothy F. Flannery [[email protected], Museums Victoria, PO Box 666, Melbourne, Victoria 3001, Australia; Alistair R. Evans [[email protected]], School of Biological Sciences, Monash University, Victoria 3800, Australia; Matt White [[email protected]], University of New England, Armidale, NSW 2351, Australia; Stephen Poropat [[email protected]], Patricia Vickers-Rich [[email protected]] School of Earth, Atmosphere and Environment, Monash University, Victoria 3800, Australia and Swinburne University of Science and Technology, Hawthorn, Victoria 3122, Australia; Alanna Maguire [[email protected]]

Key words:

• Monotremata
• Kollikodon
• Ausktribosphenidae
• Bishops
• Australosphenida
• Metatheria

Acknowledgments

First and foremost, thanks are due to the many volunteers, The 700 (Rich 2019), whose efforts over four decades have made it possible to accumulate the small collection of Cretaceous mammals now known from Victoria. Preparation of NMV P252052 was initially carried out by the late David Pickering. Discussions with William A. Clemens and Francisco Goin regarding the nature of NMV P231328 were most helpful in formulating ideas about that specimen. Thomas Martin and an anonymous reviewer read and responded to a draft of this manuscript with useful comments. A scan of the fossil by Jukka Jernvall at Biotechnology, University of Helsinki was an essential part of this project. Ms Sally Rogers-Davidson contributed to the production of several of the illustrations. Long-term support by the Committee for Research and Exploration of the National Geographic Society, the Australian Research Council, Atlas Copco, Museums Victoria, Monash University, and Swinburne University of Technology were essential in providing the wherewithal to carry out the research program that ultimately resulted in the discovery of these two fossils.