Mysterious Footprint is Believed to Belong Crocodiles That Walked On Two Legs.

June 13, 2020
crocodile on two legs

Scientists recently hit upon some set of fossilised footprints in South Korea, and they believe it belongs to crocdiles that walked on two legs.

Theses ancient footprints were first thought to belong to a pterosaur(a dinosaur) but upon careful examination, the scientists realized it may actually have been made by a large bipedal ancestor of crocodiles that lived about 110 to 120 million years ago.

These ancient giant crocodile is believe to have walked on only two legs with its tail held up proudly in the air and its feet rolling heel-to-toe while it walks, not unlike our own. It actually a bit hard to picture how they might have looked, especially because of the fact that the crocodiles we know haven't changed through millions of years of evolution. We know them to be reptiles that walks on two legs, so trying to picture otherwise is quite hard.   As matter of fact, the team of scientist almost overlooked the fact that the footprint didn't belong to a dinosaur. I mean, because of the concept that crocodiles walk on four legs and not two.

But after taking a closer look at the footprints, the fossil indentations began to look strangely familiar. The scientists found a clear impression of scales in the heel of one print, which wasn't what they were expecting.

Kyung Soo Kim from Chinju National University of Education in South Korea explained that dinosaurs couldn't have left the footprints.

"Dinosaurs and their bird descendants walk on their toes, Crocodiles walk on the flat of their feet leaving clear heel impressions, like humans do." Kyung Soo Kim explains

After taking time to futher look into the foot prints, they discovered something was missing: that's right, you guessed it, 'Hand Prints'. Hand prints were missng at the site and even though animals can sometimes walk over the prints of their front limbs with their hind limbs(a concept called over-printing) the team found no evidence of that at the site.

Anthony Romilio, a palaeontologist from the University of Queensland says the prints have fine details

"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." argues Anthony Romilio.

So after carefully analysing these impressions, they realized that while the creatures(owner of the footprint) had been moving on two legs just like way many dinosaurs once did, the footprints didn't actually belong to a dinosaur. But also modern crocodile locomotion didn't match, either.   So what could it be?

"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." Kyung Soo Kim explains
The Mystyrious Foot Prints

Trackways at the Sacheon Jahye-ri site. (Kyung Soo Kim/Chinju National University of Education)

That's an unusual gait, especially for such a big creature. The size of the footprints, which is roughly 18 to 24 centimetres (7 to 9 inches), indicates that these ancient reptiles stood up to three metres long (9.8 feet), with legs about the same height as those of an adult human. As wild as this seems at first, there might actually be precedent for such an amazing feat of balance among other ancient crocodylomorphs - the group that includes modern crocodilians and their extinct relatives.

During the Jurassic in Korea , a variety of the ancient crocodile Batrachopus is known to have had narrow tracks, which indicates a semi-terrestrial gait. But of course, these new tracks discovered are more than twice as large as any previously reported Batrachopus prints, but the authors make it clear that they closely resemble this ancient crocodile relative. The team of scientists has now identified the footprints to be of that of a potentially new species, called the Batrachopus grandis; if they're right, no other Batrachopus ichnospecies(a species identified from trace fossils) has ever been described in such detail. These anceint footprints are the largest Batrachopus sample currently known.

crocodile walking on two legs examined Prints

Photographs of well-preserved in situ Batrachopus grandis track impressions. (Kyung Soo Kim/Chinju National University of Education)

The discovery is actually fascinating. Crocodile tracks that doesn't have hand prints have never been found before in the fossil record; and maybe it's because of the fact that we've always been too quick to dismiss the idea of bipedal locomotion among ancient crocodiles.

"While most pterosaurian trackways represent quadrupedal not bipedal progression, multiple [footprint only] trackways from the Haman Formation of Korea have been erroneously attributed to giant bipedal pterosaurs. This unexpected evidence of apparently bipedal crocodylomorphs obliges us to investigate the alternative possibility that the trackway configurations represent an unusual mode of preservation, rather than bipedal locomotion, and underscores the need for a reexamination of the Batrachopodidae and other relevant, morphologically-similar ichnotaxa." the scientist recorded

[Published in Scientific Reports.]


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