Rare snake fossil offers new insight into the reptiles’ early evolution
One of the best-preserved early snake fossils, the Tametara mirim fossil dates back around 75 to 85 million years to the Cretaceous Period
Snakes first appeared during the age of dinosaurs, but fossils of many early species are so fragmentary that scientists have had difficulty deciphering their evolution as a group. Now, a well-preserved fossil from southeastern Brazil is offering fresh insight into the history of these slithering reptiles.
The fossil is of a snake called Tametara mirim that lived between 75 and 85 million years ago during the Cretaceous Period and measured about 42cm (17 inches) long. It inhabited a lush ecosystem alongside animals including enormous long-necked plant-eating dinosaurs, crocodiles, and birds.
While the fossil does not retain all of Tametara’s anatomy, a portion of the skull is so well preserved that it has enabled researchers to reconstruct the snake’s brain anatomy. The brain shape and skull bone microstructure show that this species lived a fossorial (burrowing) lifestyle, as do many present-day species such as coral snakes.
Snakes evolved from lizard ancestors and are thought to have first appeared roughly 170 million years ago during the Jurassic Period. But there are no well-preserved snake fossils from the Jurassic and only a handful from the subsequent Cretaceous, the final chapter in the age of dinosaurs.
“Snakes represent one of the most extreme body plans among all vertebrates: animals with a backbone,” says Tiago Simoes, an evolutionary biology professor at Princeton University in the US and lead author of a study about the new fossil published this week in the journal Nature.
“Understanding the origin of this peculiar and yet highly diverse group remains one of the biggest mysteries in vertebrate evolution.”