If already when we contemplate a crocodile it seems to us that we are taking a look at the remote past, now, a new investigation developed by an international team of experts, exposes us that current crocodiles cannot live up to their well-known reputation as “living fossil”, since during the 200 million years of evolution that crocodiles have on Earth, they have changed and their ancestors transform our concept of what a crocodile is. Scientists almost overlook it.
According to a study published in the journal Scientific Reports , some prehistoric crocodiles walked on two legs like dinosaurs. Experts detail fossilized footprints discovered in the Jinju Formation in South Korea (where there are abundant sets of footprints at all levels of the outcrop) that belong to a previously unknown relative of crocodiles.
“Initially it was thought that the footprints were made by a giant bipedal pterosaur walking on the marsh and now we understand that they were bipedal crocodile footprints,” says Anthony Romilio, paleontologist at the University of Queensland. “The tracks are about 24 centimeters long, which suggests they had legs roughly the same height as adult human legs . They were long animals that we estimate were over three meters long.”
This is the first evidence from this time period of a bipedal crocodylomorph . Crocodylomorpha is a branching and diverse group that includes crocodiles and their extinct relatives.
Curiosities about the footprints
By carefully analyzing the tracks, it became clear that while the creatures had been moving on two legs in the same way that many dinosaurs did, the tracks did not belong to a dinosaur. But modern crocodile locomotion didn’t match either.
“Typical crocodiles walk in a squatting position and create fairly wide footprints, explains Kyung Soo Kim of South Korea’s Chinju National University of Education.” Interestingly, these look very narrow, more like a crocodile balancing on a tightrope “.
At the time of their discovery, the enigmatic footprints measured approximately twice their width : between 18 and 24 centimeters, indicating a body length of up to 3 meters. The researchers removed large casts from the natural impressions and documented them with photos and three-dimensional photogrammetry, tracing the contours of the tracks and measuring their parameters.
An unexpected discovery
The final examination determined that the tracks belong to a new species of crocodilomorph, an early group of reptiles that are ancestors of modern crocodiles , that fed on fish and alligators, and that were more adapted to the land than other species at that time. the history. These tracks are the first to indicate a bipedal or two-legged progression, a feature previously unknown to this family. The findings could mean that footprints found elsewhere could belong to crocodylomorphs, previously thought to have been left behind by giant pterosaurs that walked on two legs to protect their wings when on land. We may have been misinterpreting the prints.
The researchers named the new species found in the Jinju Formation, Batrachopus grandis, and its fossils date from the Lower Cretaceous, which spanned 145 to 105 million years ago.
Located near the city of Jinju, South Korea, the site is home to other discoveries: it is there that scientists discovered the first tracks of a small jumping mammal, known as Koreasaltipes jinjuensis, and the first known turtle tracks in Korea.
Referencia: Trackway evidence for large bipedal crocodylomorphs from the Cretaceous of Korea, Scientific Reports (2020). DOI: 10.1038/s41598-020-66008-7
