Named Vaccaoolitus godtelpithis type of eggshell belonged to mecosuchine crocodiles and represent the oldest crocodile eggshell ever found in Australia.
The now extinct Mekosurinae were a unique native branch of the crocodile family in Australia.
These creatures dominated the continent's inland waters 55 million years ago (Early Eocene era).
They were part of a group of species that includes alligators, true crocodiles, gharials and caimans.
But the mecosuchines represent a much older lineage than the saltwater and freshwater crocodiles found in Australia today.
Modern species entered the continent much later, coming into contact with Southeast Asia about 5 million years ago.
Unlike modern crocodiles, mecosuchines occupied strange ecological niches.
“It's a strange idea. But some of them appear to have been ground hunters in the forests,” said University of New South Wales professor Michael Archer.
“There are suggestions of this among a wide range of younger mecosuchine fossils that were previously discovered in 25-million-year-old sediments from another region: the Riversleigh World Heritage Area, Boodjamulla National Park in Waani Country in north-west Queensland.”
“Some river species grew to at least 5 m in length. Some of these were apparently at least partly semi-arboreal “blob crocodiles.”
“Perhaps they hunted like leopards, leaping from trees to attack any unsuspecting thing they wanted to cook for dinner.”
Vaccaoolitus godtelpi the eggshell belongs to the oldest known member of the clade Mekosurinae.
“Said the doctor of the Museo Della, Catalan Institute of Paleontology.
“Now we can explore not only the strange anatomy of these crocodiles, but also how they reproduce and adapt to their changing environment.”
Researchers studied Vaccaoolitus godtelpi fragments of shells under an optical and electron microscope.
Their microstructure suggests that the crocodiles laid their eggs on the lakeshore and their reproductive strategy adapted to changing conditions.
“Mecodry crocodiles may have lost much of their inland territory due to land invasion – ending up having to compete on shrinking waterways not only with new arrivals to Australia, but also with declining numbers of their megafauna-sized prey,” said Dr Michael Stein, a palaeontologist at the University of New South Wales.
“Lake Murgon was surrounded by dense forest, which was also at home the world's oldest known songbirds, the earliest Australian frogs and snakes, many small mammals of South American origin, and one of the world's oldest known bats.”
According to the team, fossil eggshells are an underutilized resource in vertebrate paleontology.
“They preserve microstructural and geochemical signals that tell us not only what animals laid them, but also where they nested and how they reproduced,” Dr Panades y Blas said.
“Our research shows how powerful these fragments can be.”
“Eggshells should become a common standard component of paleontological research – collected, stored and analyzed along with bones and teeth.”
conclusions were published this week in Journal of Vertebrate Paleontology.
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Xavier Panadas and Blas etc.. The oldest crocodile eggshell in Australia: insights into the reproductive palaeoecology of Mecosuchines. Journal of Vertebrate Paleontologypublished online November 11, 2025; doi: 10.1080/02724634.2025.2560010
