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Tetrapodophis Revised – It is Not a Snake

The Early Cretaceous Tetrapodophis amplectus, as soon as thought to signify an early limbed snake, was not a snake in any case, however a member of the Dolichosauridae. The fossil is just not a lacking hyperlink between lizards and snakes however an aquatic lizard. That was the conclusion in a paper printed late final yr (2021) and at this time we check out this exceptional and extremely controversial fossil specimen.

Tetrapodophis life reconstruction.
A life reconstruction of Tetrapodophis amplectus gliding via cowl because it stalks fish near the shore. New analysis means that this Early Cretaceous reptile is just not a transitional type between a lizard and a snake, however as a substitute it’s a dolichosaurid. Image credit score: Julius Csotonyi.

A Transitional Fossil

Palaeontologists had lengthy hoped to discover a transitional fossil exhibiting a lizard-like animal with vestigial limbs, an evolutionary hyperlink within the evolution of snakes from a limbed ancestor. Tetrapodophis was named in 2015, when a scientific paper was printed describing a exceptional fossil from Brazil that had been noticed fairly by probability by scientists on a go to to a German museum.

To learn The whole lot Dinosaur’s 2015 article concerning the T. amplectus scientific paper: Fossil Snake with 4 Limbs Described.

Had Tetrapodophis been revealed to be an ancestral snake then this may have had very important implications for our understanding of the evolution of the Squamata. Nevertheless, in November 2021 a scientific paper was printed within the “Journal of Systematic Palaeontology” which concluded that the fossil had been misidentified. The analysis crew from the College of Alberta, Harvard College, Flinders College (South Australia), the College of Toronto, Midwestern College and the Universidad Maimónides (Buenos Aires, Argentina), examined the counter slab and concluded that the fossil cranium impression didn’t exhibit traits usually seen in snake skulls.

Tetrapodophis fossil.
A superbly preserved specimen as soon as thought to signify an early, limbed snake however now considered a marine lizard associated to snakes and fashionable lizards. Image credit score: Dr Dave Martill/College of Portsmouth with further annotation by The whole lot Dinosaur.

College of Alberta palaeontologist Michael Caldwell, who led the research commented:

“When the rock containing the specimen was cut up and it was found, the skeleton and cranium ended up on reverse sides of the slab, with a pure mould preserving the form of every on the other aspect. The unique research solely described the cranium and missed the pure mould, which preserved a number of options that make it clear that Tetrapodophis didn’t have the cranium of a snake — not even of a primitive one.”

Tetrapodophis Illustrated
Within the authentic 2015 scientific description, Tetrapodophis was considered an ancestral snake. The tiny limbs had been thought to have been used to carry prey. Scientists had been unsure whether or not this animal was a burrower or tailored to a marine surroundings. It has now been assigned to the Dolichosauridae. Image credit score: Julius Csotonyi.

Squamata Evolution Stays Ambiguous

The evolution of the Order Squamata stays ambiguous. It’s thought that the primary, basal squamates developed throughout the Center Triassic, however when the primary true snakes developed is unsure. The 2021 paper analyzing the cranium impression within the counter slab confirmed that Tetrapodophis lacked typical snake cranium traits. The backbone was additionally proven to lack typical snake-like anatomical traits.

The fossil file for the Squamata is especially sparse. Primitive snake and lizard skeletons are normally small with delicate bones which are simply dispersed autopsy. Palaeontologists hope that extra fossils can be discovered that assist to make clear the evolutionary origins of snakes.

A Controversial Fossil

Tetrapodophis amplectus might not signify a snake with 4 legs, transitional fossils stay elusive, it nonetheless has immense scientific worth. Co-author of the 2021 paper, Tiago Simões (Harvard College) defined:

“One of many best challenges of learning Tetrapodophis is that it is without doubt one of the smallest fossil squamates ever discovered. It’s similar to the smallest squamates alive at this time that even have lowered limbs.”

The fossil specimen stays controversial. The fossil, initially from Brazil might have been exported with out the suitable permits. It was a part of a personal assortment and the authorities in Brazil solely grew to become conscious of the fossil’s existence when the 2015 paper was printed.

To learn an article concerning the authorized dispute: Fossil Slithers into Authorized Dispute.

The whole lot Dinosaur acknowledges the help of media releases from Flinders College and the College of Alberta within the compilation of this text.

The scientific paper: “Tetrapodophis amplectus is just not a snake: Reassessment of the osteology, phylogeny and useful morphology of an Early Cretaceous dolichosaurid lizard” by M. W. Caldwell, T. R. Simões, A. Palcid, F. F. Garberoglio, R. R. Reisz, M. S. Y. Lee and R. L. Nydam printed within the Journal of Systematic Palaeontology (November 2021).



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