Scientists at the University of New South Wales have annoounced a major fossil find near Murgon, just west of Gympie in the South Burnett region.
They say the find involves egg shells potentially from Australia’s earliest ancient crocodile – one that climbed trees and dropped on its prey.
A spokesperson said the discovery of Australia’s oldest known crocodile eggshells is helping unlock clues to ancient ecosystems.
The find, on a Murgon district grazing property, follows decades of digging in what looks like an unremarkable clay pit.
“But within the clay lies one of Australia’s oldest fossil sites – a window back in time to when the continent was still connected to Antarctica and South America.
“Now, an international team led by the Institut Català de Paleontologia Miquel Crusafont, including researchers from UNSW Sydney, has uncovered the oldest crocodilian eggshells ever found in Australia.
“This group of now extinct crocs dominated inland waters 55 million years ago. Modern saltwater and freshwater crocs only arrived around 3.8 million years ago.
“These eggshells have given us a glimpse of their intimate life history,” says the study’s lead author Xavier Panadès i Blas.
“Unlike today’s saltwater and freshwater crocodiles, they filled strange ecological niches.
UNSW palaeontologist Professor Michael Archer, says there are suggestions of this through younger fossils discovered in northwestern Queensland.
Prof Archer says some riverine species there grew to at least five metres long.
“Some were also apparently at least partly semi-arboreal ‘drop crocs’,” he says.
“They were perhaps hunting like leopards – dropping out of trees on any unsuspecting thing they fancied for dinner.”
Panadès i Blas says eggshells are an underused resource in vertebrate palaeontology.
Coauthor Dr Michael Stein says the crocs may have lost much of their inland territory because of encroaching dryland – eventually having to compete in the shrinking waterways not only with new arrivals to Australia, but dwindling numbers of their megafaunal-sized prey as well.
Dr Stein says the Murgon lake was surrounded by a lush forest.
Prof Archer says the Murgon discovery is part of a much bigger story – one that enriches the understanding of ancient ecosystems before Australia became an independent continent.
While this has since been confirmed, at the time it seemed so strange to Prof Archer that he consulted Professor Max Hecht – a reptile specialist at the American Museum of Natural History.
“When he saw it, Max nearly dropped his coffee cup,” Prof. Archer says.
“It closely resembled another kind of extinct croc with dinosaur-type teeth that had been found in South America.
Prof. Archer says he and his colleagues have been excavating in the Murgon area since 1983.
“That year, UNSW colleague Henk Godhelp and I drove to Murgon, parked the car on the side of the road, grabbed our shovels, knocked on the door and asked if we could dig up their backyard,” Prof. Archer says.
“After explaining the prehistoric treasures that might lie under their sheep paddock and that fossil turtle shells had already been found in the area, they grinned and said, ‘Of course!”.
