A uncommon 3-D snake fossil is spilling secrets and techniques of its uncommon life-style

Most snake fossils are two-dimensional. Sandwiched inside rocks, the stress of hundreds of thousands of years flattens them like a pancake. But in 2020, scientists uncovered a uniquely well-preserved snake fossil in southeastern Brazil. The snake’s tiny cranium — solely 20 millimeters in size — was 3-D, with its braincase nonetheless intact.  

The fossil’s well-preserved cranium has now offered the earliest concrete evidence of a fossorial snake — a serpent that burrowed underground. And that means early snakes explored extra habitats and life than beforehand thought, researchers report July 22 in Nature.  

The fossil belongs to a beforehand unknown snake species that lived 85 million to 75 million years in the past. Researchers named it Tametara mirim, after the phrases for “adorned” and “small-sized” within the Tupí-Guaraní language of Brazil. It is considered one of solely 4 snake fossils from the Age of Dinosaurs preserved this properly.  

“This quality of preservation allows us to answer questions you simply cannot answer if you don’t have the right body parts preserved,” says ​​paleobiologist Tiago Simões of Princeton University.  

Unlike human brains, which float in fluid inside our skulls, the form of snake brains intently matches the within of their braincase. Using CT scans, the researchers reconstructed T. mirim’s mind anatomy. Well-developed mind areas correspond to the senses the snake relied on most. 

T. mirim had a poorly developed optic lobe, so it most likely couldn’t see very properly. But its otic capsule, a bony construction that protects the internal ear, was enlarged — a function typically seen in snakes that sense vibrations. It additionally had an unusually thick cranium. These options counsel T. mirim lived underground, digging tunnels by butting its head in opposition to the dust.  

The atmosphere the place snakes first originated stays a thriller. But the earliest identified snake ancestor — which lived 167 million years in the past — might have been considerably tailored for an underground life-style, although was not almost as good at burrowing as T. mirim, Simões says.  

By the Cretaceous Period, snakes have been swimming, slithering and, in T. mirim’s case, digging. Simões says the obvious improve in variety within the Cretaceous might be as a result of snakes developed new sensory features and talents in a short time or as a result of they have been various all alongside. Finding new fossils with intact braincases might assist resolve that debate. 

What is obvious is that early snake evolution was way more complicated than beforehand thought, says ​​Michael Caldwell, a paleontologist at the University of Alberta in Edmonton, Canada, who was not concerned within the analysis. The snake household tree most likely included many branching lineages with their very own distinctive anatomies and life.  

To higher perceive how snakes diversified into all their fashionable kinds, scientists might want to discover fossils that present the transitions between totally different life. “When organisms become highly specialized for a particular environment, they don’t become so in the blink of an eye,” Simões says. “What we have today are the endpoints of a very long evolutionary history.”