4-legged ‘snake’ fossil is actually a different ancient animal, new study finds

A dinosaur-age fossil touted as the first four-legged snake known to science might actually be an entirely different beast, according to a new study.

The tiny fossil, about the length of a pencil to 7.7 inches (19.5 centimeters) long, is probably a dolichosaurus, a now extinct marine lizard with an elongated body that lived during the Cretaceous period (145 million to 66 million years ago), the study researchers found.

After studying the remains of the creature, known as Tetrapodophis amplectus (the genus in Greek means “four-legged snake”, while the species means “to kiss”) in Latin, the new team discovered that the specimen lacks key anatomical features characteristic of snakessaid Michael Caldwell, principal investigator of the study, professor in the Department of Biological Sciences and chair of the Faculty of Science at the University of Alberta in Edmonton, Canada.

What’s more, the new study explodes the treatment of Tetrapodophis fossil, which may have been illegally exported from Brazil and whose original study did not include any Brazilian researchers, despite a Brazilian law requiring researchers from their country to be included in the study of Brazilian specimens.

Related: Photos: The strange 4-legged snake was a transitional creature

Scientists have long postulated that the ancestors of snakes had four legs; two 2016 studies in the newspaper Cell who examined the genetics of snakes suggested that snakes lost their limbs around 150 million years ago due to genetic mutation, and other research has even found fossil evidence of a two-legged snake. Corn Tetrapodophis, the discovery of which was announced in 2015 in the journal Science, remains the only fossil of four-legged snake recorded.

The 2015 study suggested that when he was alive 120 million years ago, Tetrapodophis used its four limbs, each with five fingers, not for walking but to grab mates during mating and grab combative prey while hunting, Previously reported live science. This animal was likely part of the transition from ancient lizards to modern snakes, and likely evolved from terrestrial burrowing animals, the researchers said.

But this interpretation of the fossil did not suit Caldwell and Robert Reisz, co-author of the new study and a vertebrate paleontologist at the University of Toronto. So they flew to Germany, where the private fossil was on display at the Solnhofen Museum (formerly known as the Bürgermeister-Müller-Museum) to do their own microscopic assessment of Tetrapodophis, which they first presented at the Society of Vertebrate Paleontology annual meeting in 2016.

New discoveries

The new team found evidence that Tetrapodophis looked more like a lizard than serpentine, especially in the skull, the researchers reported in the new study, published online Nov. 17 in the Journal of Systematic Paleontology. Most of the skull bones have been “crushed like an eggshell,” with pieces of the skull shattered on a plate and the natural mold of the skull on the counterpart, Caldwell said. “The only thing that was completely ignored by the original writers is the skull counterpart,” he said. “It’s in the natural mold where we see other characteristics that are lizards, not snakes.”

The researchers found that Tetrapodophis’ neither was the body like a serpent. For example, the skinny Tetrapodophis The fossil lacks zygosphenes and zygantra, the stabilizing systems of the vertebrae that help a snake squeeze back and forth, and it has long, straight ribs, indicating that it was a swimmer and not a swimmer. a digger, as the original study said. “Burrowing creatures tend to be long and tubular,” Caldwell said.

Dolichosaurs are closely related to snakes, said study co-author Tiago Simões, a postdoctoral researcher at Harvard University’s Museum of Comparative Zoology. So it is perhaps not surprising that the original authors thought that Tetrapodophis was a snake, the researchers said.

However, this is not an open and closed case. “Tetrapodophis is a fantastic fossil, showing a unique combination of features not seen in any other squamate [lizards, snakes and amphisbaenians]said Bruno Gonçalves Augusta, associate researcher at the Museum of Zoology at the University of São Paulo and Southern Methodist University in Texas, who was not involved in any of the studies. But some of the new findings from the counterpart fossil, or mold, should be handled with caution, he said.

“For example, I don’t agree with their interpretation of the square [skull bone] morphology, since the actual bone is not preserved on the fossil, only a natural impression (a mold) is present… which in my opinion is not a reliable source of information, ”said Gonçalves Augusta to Live Science in an email.

Other scientists cannot get an independent overview of the fossil because the private specimen is not available to scientists, Gonçalves Augusta added. “It’s not even possible to make first-hand observations and properly study the specimen anymore,” he said.

Part and counterpart of Tetrapodophis. (Image credit: Michael Caldwell)

Ethical dilemma

The original researchers maintain their interpretation of the fossil, which they say shows “the animal is the oldest and most primitive snake known,” David Martill, co-investigator of the 2015 study and professor of paleobiology at the University of Portsmouth in the UK, said Live Science.

The fossil comes from the Crato Formation in Brazil, which was largely excavated in the 1970s and subsequent decades. It means that Tetrapodophis was probably withdrawn from the country after the 1942 Legislative Decree, which stipulated that holotypes (the first specimen discovered of a new species) must remain in Brazil and that paratypes (fossils of a species subsequently discovered) should not can be exported only with permits, the researchers of the new study said. Because the origin of Tetrapodophis is unknown but highly suspect, Brazilian federal police have opened an investigation into him, the researchers wrote in the new study.

Martill noted that “We would be happy to see the fossil returned to Brazil, but it was not our fossil, and therefore not our decision.” But he said the law surrounding Brazil’s fossil exports was not always enforced in the 1970s and 1980s (which the new team says is no excuse for breaking the law).

“I have no problem with these fossils going back to Brazil, as long as Brazil doesn’t burn its museums,” Martill said. “I mean, they had this huge tragedy when their Rio Natural History Museum[deJaneiro[deJaneiro[deJaneiro[deJaneiro burnt. “

But the 2018 fire is unlikely to have played a role in this affair, the authors of the new study said. “Unless Dr Martill is prescient, I find it hard to believe that he was predicting future fires in a museum as he stood in a private museum in Solnhofen and saw the fossil for the first time two or more times. three years before his 2015 article, ”Caldwell told Live Science in an email.

Others supported the return of the fossil to Brazil.

“I agree when the authors say how important it is for the fossil to be returned to a public research institute in Brazil,” said Gonçalves Augusta. “Fossils are an important part of a country’s heritage, and they should be available for any scientific study, which is not the case for Tetrapodophis at this moment.”

Originally posted on Live Science.

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