In the shallows near the shore, there is a tangle of branches from a conifer that have fallen into the water, sharing this habitat with a water bug in the family Belostomatidae and small fish. Credit: Julius Csotonyi.
It would be a dream come true for paleontologists to fill in the links of the evolutionary chain with a fossil record of a snake with four legs. The specimen thought to be the missing piece of the puzzle is actually a different specimen.
"It has been known for a long time that snakes are members of a group of four-legged animals that have lost their limbs due to evolutionary specializations," said Caldwell, the lead author of the study.
The ancestral form of ancient snakes had four legs. It has been predicted for a long time that a snake with four legs would be found as a fossil.
A missing link has been discovered.
A team of researchers published a paper in the journal Science in 2015, which reported the discovery of a four-legged snake fossil.
This would be a very important discovery if it was correctly interpreted.
According to Caldwell, the new study of Tetrapods revealed a number of mischaracterizations of the specimen, suggesting that this might be the long-sought-after snake with four legs.
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 conclusion of our team is that the snake that was misclassified is not a snake at all. All aspects of its body are indistinguishable from the dolichosaurs, a group of extinct marine lizards from the Cretaceous period.
Part and Counterpart of the same thing. Credit: Michael Caldwell.
There were clues in the rock the fossil was taken from.
The skeleton and skull were put on opposite sides of the slab after the rock was split, with a natural mould preserving the shape of each on the opposite side. The original study only described the skull and overlooked the natural mould, which preserved several features that make it clear that the skull of a snake was not even a primitive one.
A controversial specimen.
The study's author, a former U of A graduate student and Harvard post- doctoral fellow, said that the snake with four legs still has a lot to teach us.
One of the biggest challenges of studying Tetrapodophis is that it is one of the smallest fossil squamates ever found. It is comparable to the smallest squamates alive that have reduced limbs.
Access to the specimen is one of the challenges of studying the Tetrapods.
There were no appropriate permits for the specimen's original removal from Brazil and it has been housed in a private collection with limited access to researchers. Simes said the situation was met with a backlash from the scientific community.
The legal status of the specimen is laid out in our redescription and we emphasize the need for its return to Brazil in accordance with Brazilian legislation and international treaties.
The study, "Tetrapodophis amplectus is not a snake: Reassessment of the osteology, phylogeny and functional morphology of an Early Cretaceous dolichosaurid lizard," was published in the Journal of Systematic Palaeontology.
The Journal of Systematic Palaeontology has more information about the re-assessment of the osteology, phylogeny and functional morphology of an Early Cretaceous dolichosaurid lizard. There is a DOI: 10.1080/1477.
The Journal of Systematic Palaeontology is a science journal.
Paleontologists debunk fossil thought to be missing link between lizards and first snakes.
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