Ancient eggshells shed new light on crocodiles that hunted prey from trees

Scientists say they have unearthed Australia’s oldest known crocodile eggshells, a discovery that could shed light on ancient reptiles that may have hunted their prey by dropping them from trees.

The eggshells belonged to mekosuchine crocodiles, a prehistoric creature that dominated Australian waters 55 million years ago, long before saltwater and freshwater crocodiles arrived on the continent around 3.8 million years ago.

Paleontologist Michael Archer said mekosuchine crocodiles could grow to at least 5 meters (about 16 feet) long and some hunted in trees. Australian researchers have nicknamed them “drop fangs”, a reference to the dreaded “drop bear” – the vicious, carnivorous cousin of the country’s beloved koalas, or so the legend goes.

“It’s a bizarre idea. But some of them appear to have been terrestrial hunters in the forests,” said Archer, a professor at the University of New South Wales in Sydney who was involved in the study.

“They may have been hunting like leopards, dropping from the trees onto whatever they unsuspectingly took their fancy for dinner,” he said in a statement.

A team of international scientists, led by the Institut Català de Paleontologia Miquel Crusafont in Barcelona, ​​dug up the fossils from a rancher’s garden in south-east Queensland and studied them.. They reported their findings Tuesday in the Journal of Vertebrate Paleontology.

Ancient crocodile egg shells help scientists understand the anatomy of these reptiles, as well as their reproductive patterns and adaptability, said the study’s lead author, Xavier Panadès i Blas.

“They preserve microstructural and geochemical signals that tell us not only what types of animals laid them, but also where they nested and how they reproduced,” he said in the release.

Mekosuchine crocodiles are thought to have disappeared from Australia around 3,000 years ago. They may have lost much of their interior habitat due to dryland encroachment, a situation made worse by increasing competition with other predators and declining prey numbers, said co-author Michael Stein, a research associate at the University of New South Wales.

A treasure in the garden

The exact location of the discovery is a small town called Murgon, about three and a half hours’ drive from Brisbane, the capital of Queensland.

Archer said he and his colleagues have been digging there since 1983 and he still remembers how it all started.

“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 their garden,” he said.

Residents “smiled and said ‘sure'” after learning their homes were based on prehistoric treasures, Archer recalls.

“And, obviously, thanks to the many fascinating animals we have already found in this deposit since 1983, we know that as we dig deeper, there will be many more surprises to come,” he said.

It’s inherently difficult to identify an extinct species from an eggshell, said Dean Lomax, a paleontologist and author of “The Secret Life of Dinosaurs – Unearthing the Real Behaviors of prehistoric animals. He was not involved in the new research.

However, given that the eggshell was found in the same geologic deposits and locality as the only known mekosuchine fossils from that period, Lomax said the authors make a strong case.

“I think one of the key things here is that the match between fossil eggshells and the crocodile that laid them can provide new information,” he said. “This will help us understand not only how they reproduced and where they laid their eggs, but this connection could also help shed light on the lifestyle of these unusual crocodiles.”

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