55m-year-old eggshells unearthed in Queensland could also be older relative of notorious ‘drop crocs’ | Crocodiles

Scientists have recognized what are believed to be the oldest crocodilian eggshells ever present in Australia, unearthed in a grazier’s again yard in regional Queensland.

The 55m-year-old eggshells – discovered at a fossil deposit in Murgon, roughly 270km north-west of Brisbane – seemingly belong to a gaggle of extinct crocodiles often known as mekosuchines, new analysis suggests.

Modern saltwater and freshwater crocodiles solely arrived in Australia about 3.8m years in the past. “Before they got here, these weird mekosuchine crocs were all over the place,” stated examine co-author Prof Michael Archer, a palaeontologist on the University of New South Wales.

Some mekosuchines have been partial tree dwellers, such because the ridge-headed crocodile, which has been nicknamed the “drop croc” as a result of it might have climbed timber and dropped on to animals passing beneath.

“The idea of ‘drop crocs’ isn’t as crazy as it sounds. We probably did have crocodiles that were spending time in the trees and jumping out on prey,” Archer stated.

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The fossil eggshells discovered at Murgon seemingly belonged to an earlier genus of mekosuchines often known as Kambara.

“We know we’re looking at the oldest crocodile eggshells certainly in Australia … the Kambara mekosuchines are the first ones we know of this whole group,” Archer stated.

The analysis targeted on 12 fossil eggshells that have been by the way collected over a number of years within the Nineteen Nineties, however which have been solely lately analysed by examine lead creator, Dr Xavier Panadès i Blas of the Miquel Crusafont Catalan Institute of Palaeontology in Barcelona.

He stated eggshells “preserve microstructural and geochemical signals that tell us not only what kinds of animals laid them, but also where they nested and how they bred”.

“Eggshells should be a routine, standard component of palaeontological research – collected, curated and analysed alongside bones and teeth,” he stated in a press release.

The construction of the mekosuchine eggshells “do not resemble any other crocodilian eggshells”, Archer stated, pointing to their affiliation with a crocodile group distinctive to Australia.

“We still do not know what the relationships of this group of crocodiles is to all the other crocodiles of the world. All we do know is that when the salt and freshwater crocodiles did get into Australia … that was the beginning of the end for this particular group.”

Dr Matthew McCurry, a vertebrate palaeontologist on the Australian Museum who was not concerned within the analysis, stated mekosuchines have been “representative of the fact that crocodiles in the past did a lot more than they do in modern ecosystems”.

“If we go right back to the Cretaceous [period, 66m to 143m years ago], crocodiles did a huge range of different things: some were fully marine and had paddle-like limbs, some fed on plants exclusively,” he stated.

“When most people think palaeontology, they think of the bones and the teeth of the organisms – they’re often the parts that fossilise the most easily. Trackways are probably the second most common thing … footprints left behind.

“We occasionally do find the bones of these animals, but eggs are comparatively more rare.”

The examine was printed within the Journal of Vertebrate Paleontology.