Researchers Stunned to Discover Ancient Crocodiles That Walked on Two Legs

James Marshall
June 12, 2020

The discovery of large well-preserved footprints belonging to an ancestor of modern-day crocodiles from the Lower Cretaceous Jinju Formation of South Korea is reported this week in Scientific Reports.

Some species of ancient crocodiles of more than three metres in length, walked on its two hind legs as if they were dinosaurs.

The researchers say the animal that made the tracks represents a previously unknown species of crocodylomorph, a large group of animals containing modern-day crocodilians-such as crocodiles and alligators-as well as their extinct relatives.

"As an animal walks, the hind feet have the potential of stepping into the impression made by the hand and "over-printing" it, but we find no evidence of this at these Korean sites", Anthony Romilio, another author of the study from the University of Queensland, Australia, said in the statement.

At first, they thought the footmarks were from a winged ancient reptile known as a pterosaur.

"We ruled out swimming because the trackways are so regular", said Martin Lockley, a paleontologist and professor at the University of Colorado and an author of the study.

The team named the 18-24 cm-long tracks Batrachopus grandis emphasizing the large size in comparison with much older and smaller 2-3 long cm tracks of the Batrachopus type, commonly found in the Jurassic of North America.

The research team, led by Professor Kyung Soo Kim from Chinju National University of Education, soon realised why.

The footprints of the ancient crocodile at the Sacheon Jahye-ri site in South Korea
Researchers Stunned to Discover Ancient Crocodiles That Walked on Two Legs

They said the consistent absence of forelimb prints and the narrow trackwaypointed to a new species that walked on two legs. Also, poorly preserved tracks of a bipedal animal in 2012 in a South Korean rock unit created the "mystery" of a unique creature.

Similar "enigmatic" footprints found at other sites in South Korea had been thought to belong to giant pterosaurs - prehistoric flying reptiles - walking on two legs. This, plus the lack of markings of drag of the tail, it was obvious that these creatures were moving, so the biped.

"They were moving in the same way as many dinosaurs, but the footprints were not made by dinosaurs".

Nor is it due to a bad conservation, as these fossils are, in the words of the researcher, "spectacular, even preserved the fine detail of the pads and the scales on the soles of the feet".

While palaeontologists knew that some crocodiles from the "age of dinosaurs" were more adapted to life on land than their modern relatives, these were small animals about one meter long with footprints showing they walked on all fours.

The ancient crocodiles most likely would have walked flat on their feet, digging their heels into the earth much like humans do - leaving deep, narrow impressions.

"Fossil crocodile tracks are quite rare in Asia, so finding an abundance of almost one hundred footprints was extraordinary".

Other reports by Click Lancashire

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