” Somewhere in the fossil record of ancient snakes is an ancestral kind that still had four legs. It has thus long been anticipated that a snake with four legs would be discovered as a fossil.”
Missing link discovered?
In a paper published in the journal Science in 2015, a team of researchers reported the discovery of what was believed to be an example of the first recognized four-legged snake fossil, an animal they named Tetrapodophis amplectus.
” If properly interpreted based on the preserved anatomy, this would be an extremely crucial discovery,” stated Caldwell
Part and Counterpart of Tetrapodophis. Credit: Michael Caldwell.
Caldwell described that the brand-new research study of Tetrapodophis revealed a variety of mischaracterizations of the anatomy and morphology of the specimen– characteristics that initially seemed to be shared most closely with snakes, recommending this might be the long-sought-after snake with four legs.
” There are numerous evolutionary questions that might be addressed by discovering a four-legged snake fossil, but just if it is the genuine deal. The major conclusion of our team is that Tetrapodophis amplectus is not in truth a snake and was misclassified,” stated Caldwell. “Rather, all elements of its anatomy are constant with the anatomy observed in a group of extinct marine lizards from the Cretaceous period referred to as dolichosaurs.”
The ideas to this conclusion, Caldwell noted, were hiding in the rock the fossil was extracted from.
” When the rock including the specimen was divided and it was discovered, the skeleton and skull ended up on opposite sides of the slab, with a natural mould protecting the shape of each on the opposite side,” stated Caldwell. “The initial research study only described the skull and ignored the natural mould, which maintained several functions that make it clear that Tetrapodophis did not have the skull of a snake– not even of a primitive one.”
A questionable specimen
Tetrapodophis may not be the snake with four legs that paleontologists reward, it still has much to teach us, stated research study coauthor Tiago Simões, a previous U of A PhD student, Harvard post- doctoral fellow and Brazilian paleontologist, who pointed out some of the functions that make it unique.
” One of the best obstacles of studying Tetrapodophis is that it is one of the tiniest fossil squamates ever discovered,” stated Simões. “It is equivalent to the smallest squamates alive today that likewise have actually reduced limbs.”
An extra difficulty to studying the Tetrapodophis is access to the specimen itself.
” There were no appropriate permits for the specimens initial removal from Brazil and, because its initial publication, it has actually been housed in a private collection with restricted access to scientists. The situation was met a large backlash from the scientific community,” said Simões.
” In our redescription of Tetrapodophis, we lay out the crucial legal status of the specimen and stress the necessity of its repatriation to Brazil, in accordance not just with Brazilian legislation but likewise international treaties and the increasing global effort to decrease the impact of colonialist practices in science.”
Referral: “Tetrapodophis amplectus is not a snake: Reassessment of the osteology, phylogeny and practical morphology of an Early Cretaceous dolichosaurid lizard” by Michael W. Caldwell, Tiago R. Simões, Alessandro Palci, Fernando F. Garberoglio, Robert R. Reisz, Michael S. Y. Lee and Randall L. Nydam, 17 November 2021, Journal of Systematic Palaeontology.DOI: 10.1080/ 14772019.2021.1983044.
“In the shallows near shore, Tetrapodophis amplectus glides through a tangle of branches from the conifer Duartenia araripensis that have fallen into the water, sharing this environment with a water bug in the household Belostomatidae and small fish (Dastilbe sp.).” Credit: Julius Csotonyi
University of Alberta researcher and collaborators reveal that a proposed “snake with 4 legs” is rather a long-bodied marine lizard.
Completing the links of the evolutionary chain with a fossil record of a “snake with four legs” linking lizards and early snakes would be a dream come real for paleontologists. But a specimen formerly believed to fit the bill is not the missing out on piece of the puzzle, according to a brand-new Journal of Systematic Palaeontology research study led by University of Alberta paleontologist Michael Caldwell.
” It has long been understood that snakes are members of a family tree of four-legged vertebrates that, as a result of evolutionary expertises, lost their limbs,” said Caldwell, lead author of the study and teacher in the departments of biological sciences and earth and atmospheric sciences.