Palaeontologists from the University of Queensland have discovered that some ancient species of crocodiles walked on their hind legs like dinosaurs.
The researchers have been studying ancient fossilised footprints that they had initially attributed to pterosaurs but have since revealed that the prints were made by crocodiles that would have measured over three metres in length.
Dr Anthony Romilio from the University of Queensland said: “At one site, the footprints were initially thought to be made by a giant bipedal pterosaur walking on the mudflat, we now understand that these were bipedal crocodile prints,” Dr Romilio said.
The study has found that the footprints measure around 24 centimetres, suggesting the track-makers had legs about the same height as human adult legs but the prints appeared to lack any handprints.
The research team, led by Professor Kyung Soo Kim from Chinju National University of Education, soon found clues as to why there were no handprints.
“Typical crocodiles walk in a squat stance and create trackways that are wide. Oddly, our trackways are very narrow looking – more like a crocodile balancing on a tight-rope. When combined with the lack of any tail-drag marks, it became clear that these creatures were moving bipedally. They were moving in the same way as many dinosaurs, but the footprints were not made by dinosaurs. Dinosaurs and their bird descendants walk on their toes whilst crocodiles walk on the flat of their feet leaving clear heel impressions like humans do.” said Professor Kim.
The footprints dated between 110-120 million years ago and were discovered after analysing animal track sites in what is now known as South Korea.
Researchers initially questioned the absence of hand impressions from the trackways, given that today’s typical crocodiles are ‘four-legged’ or quadrupedal.
“Fossil crocodile tracks are quite rare in Asia, so finding an abundance of nearly one hundred footprints was extraordinary,” Dr Romilio said.
“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.
“It isn’t due to poor preservation either, because these fossils are spectacular, they even have the fine details of the toe-pads and scales on their soles preserved.”
Header Image – A reconstruction of the ancient landscape of South Korea with crocodile track-makers. Image Credit : Dr Anthony Romilio