Eusuchian crocodyliform
»  click here to see where Isisfordia sits in the crocodilian family tree

98-95 million years old (Early Cretaceous; Albian-Cenomanian) 

Life reconstruction of Isisfordia duncani. 
Artwork: © 2006 Matt Herne

Geological Formation
Winton Formation 

»  A near complete, articulated skeleton (holotype)
» A complete skull (paratype)
» A partial, articulated skeleton
» A partial lower jaw (paratype)

Adult size
» 1.1 metres
» 3-4 kilograms

Discovery site
Near the town of Isisford, central-western Queensland, Australia

The first fossils of Isisfordia were found in the mid-1990s by the former Deputy Major of Isisford, Ian Duncan, after whom the species is named. Subsequent fieldwork by our team from the University of Queensland during 2003, 2004 and 2005 resulted in the discovery of more fossils, among them a complete skull. 

Isisfordia duncani is the world's most primitive eusuchian crocodyliform (modern crocodilian). It lived almost 100 million years ago in what is now western Queensland, near the outback town of Isisford. As a semi-aquatic ambush predator, it inhabited the lakes and swamps that formed the vast river plains in the basin that was formerly the Eromanaga Sea - an inland sea that covered much of Queensland and central Australia at least four times during the Early Cretaceous. 

Isisfordia shared its world with dinosaurs such as titanosauriform sauropods, theropods and wallaby-sized ornithopods (shown in the background on the illustration to the right). The tracks of the latter two dinosaurs are preserved in stone at Lark Quarry Conservation Park. Like today's crocodilans, Isisfordia was probably an opportunistic feeder, and would have eaten fish, lizards, frogs and invertebrates, such as snails, crustaceans and insects. Anything up to its own body size is likely to have been fair game. 

The appearance of Isisfordia signalled the dawn of crocodilians as we know them today. Living 98-95 million years ago, it predates the first recorded appearance of alligators and gharials by almost 20 million years, and the first true crocodiles by over 30 million. The discovery of this new crocodilian in Australia indicates that the precursors to all three groups of modern crocodilians may have originated in Gondwana, rather than Europe or North America, as was previously thought.

Salisbury, S. W., Molnar, R. E., Frey, E. & Willis, P. M. A. 2006. The origin of modern crocodyliforms: new evidence from the Cretaceous of Australia. Proceedings of the Royal Society of London, Series B, doi:10.1098/rspb.2006.3613. pdfESM