Filling in the links of the evolutionary chain with a fossil record of a ”snake with four legs” connecting lizards and early snakes would be a dream come true for paleontologists. But a specimen formerly thought to fit the bill is not the missing piece of the puzzle, according to a new Journal of Systematic Palaeontology study led by University of Alberta paleontologist Michael Caldwell.
“It has long been understood that snakes are members of a lineage of four-legged vertebrates that, as a result of evolutionary specializations, lost their limbs,” said Caldwell, lead author of the study and professor in the departments of biological sciences and earth and atmospheric sciences.
“Somewhere in the fossil record of ancient snakes is an ancestral form that still had four legs. It has thus long been predicted that a snake with four legs would be found as a fossil.”
In a paper published in the journal Sciencein 2015, a team of researchers reported the discovery of what was believed to be an example of the first known four-legged snake fossil, an animal they named Tetrapodophis amplectus.Taylor & Francis Group, “Paleontologists debunk fossil thought to be missing link between lizards and first snakes” at ScienceDaily (November 18, 2021)
This was the story in 2015:
So what happened?
“There are many evolutionary questions that could be answered by finding a four-legged snake fossil, but only if it is the real deal. The major conclusion of our team is that Tetrapodophis amplectus is not in fact a snake and was misclassified,” said Caldwell. “Rather, all aspects of its anatomy are consistent with the anatomy observed in a group of extinct marine lizards from the Cretaceous period known as dolichosaurs.”Taylor & Francis Group, “Paleontologists debunk fossil thought to be missing link between lizards and first snakes” at ScienceDaily (November 18, 2021)
In any event, inconveniently, there is also a snarl about removing the fossil from Brazil.
So researchers are still looking for a snake with legs.
The paper is open access.