Surprise with the 'four-legged snake' that appeared 110 million years ago

Paleontologists claim to have found evidence of a link between snakes and lizards.

Six years ago, paleontologists were shocked to discover a species of "four-legged snake". The fossil was discovered in Brazil and thanks to it, scientists have found the missing link in the evolutionary tree of snakes and lizards.

The discovery of the "four-legged snake" made scientists extremely excited. (Photo: James Brown/UOP)

The study dated the strange creature to about 110 million years ago - in the Early Cretaceous - they named the creature Tetrapodophis amplectus.

Dr Dave Martill from the University of Portsmouth, UK, whose paper was published in the journal Science, said at the time: "This fossil answers some very important questions, such as: such as snakes that evolved from burrowing lizards, not from marine lizards".

But there's still a small problem: Researchers aren't entirely convinced that Tetrapodophis amplectusr is a snake.

According to new analysis by researchers at the University of Alberta, Canada, this reptile is most likely a long-bodied, marine lizard. This idea was unexpectedly suggested by paleontologist Michael Caldwell, who presented his findings in the Journal of Systemic Paleontology. "It has long been believed that snakes are members of the family of tetrapods, which, as a result of evolutionary specialization, have lost their limbs," he said.

He further explained: "Somewhere in the fossil record of ancient snakes, they still had four legs. Therefore, it was predicted that the discovery of a fossil of a snake with four legs was premature. or later."

Tetrapodophis amplectus is most likely a lizard, not a snake. (Photo: Julius Csotonyi).

In the original 2015 study, researchers claimed to have found the first evidence of a four-legged snake. "This will be a very important discovery," said Professor Caldwell.

However, he believes that the initial analysis suffered from "some deviations" in the anatomy and morphology of the organism. These features appear closely related to snakes at first glance, but according to the new analysis, the creature's features are more consistent with those of dolichosaurs.

The paleontologist said: "There are many evolutionary questions that can be answered through the discovery of four-legged snake fossils, but only if it is true. The main conclusion of our group is that Tetrapodophis amplectus is not in fact a snake and has been misclassified. Instead, all aspects of its anatomy are consistent with the extinct Cretaceous group of sea lizards known as the dolichosaurs."

The expert and his colleagues made these conclusions based on the fossils that were extracted. 'When the rock containing the specimen was split, the skeleton and skull ended up lying on opposite sides of the slab, with a natural mold that kept the shape of the opposite face,' he explains. originally described only the skull and omitted the natural mold, but in fact there are some features that clearly indicate that Tetrapodophis did not have the skull of a snake - not even that of a primitive animal".

Despite the shocking claims, researchers say fossils can still reveal a lot about the past.

According to study co-author Tiago Simões, a Brazilian paleontologist and former University of Alberta graduate student, Tetrapodophis has many unique features of interest to paleontologists. "One of the biggest challenges studying Tetrapodophis is because it's one of the smallest scale fossils ever found," he said.