Scientists Discover Rare 3D Snake Fossil That Changes What We Know About Early Snakes

KEY POINTS

• Scientists discovered a rare 3D snake fossil from up to 85 million years ago.
• The fossil suggests the ancient snake was specially adapted for underground life.
• Its preserved skull helped researchers reconstruct parts of its brain and senses.
• The discovery shows early snakes developed diverse lifestyles much earlier than known.

Scientists have identified a rare three-dimensional fossil of an 85 million- to 75 million-year-old snake that provides the earliest clear evidence of a snake adapted to living underground. The fossil, discovered in southeastern Brazil in 2020 and described in the journal Nature on July 22, 2026, includes an unusually intact skull and braincase that allowed researchers to reconstruct parts of the animal’s brain and uncover clues about how it lived during the age of dinosaurs.

The newly identified species, named Tametara mirim, is important because most ancient snake fossils are crushed flat over millions of years. The new specimen remained preserved in three dimensions, giving researchers a rare look at the senses and behavior of an early snake.

The discovery suggests that snakes had already developed highly specialized lifestyles, including underground burrowing, much earlier than the fossil record had clearly shown.

Tiny Skull Preserved in Three Dimensions

The fossil’s skull measures only about 20 millimeters long, but its exceptional condition makes it one of the most valuable snake fossils from the dinosaur era. According to the researchers, it is one of only four known snake fossils from that period preserved at this level of quality.

Paleobiologist Tiago Simões of Princeton University told Science News that the fossil’s exceptional preservation allows researchers to investigate aspects of early snake biology that would otherwise remain inaccessible.

“This quality of preservation allows us to answer questions you simply cannot answer if you don’t have the right body parts preserved,” Simões told Science News.

Scientists used CT scans to examine the fossil without damaging it. Because a snake’s brain closely follows the shape of the inside of its braincase, the team could use the scans to reconstruct important features of T. mirim’s brain.

The results revealed an animal apparently built for life beneath the surface.

The snake had a poorly developed optic lobe, suggesting that vision was not one of its strongest senses. Its otic capsule, the part of the skull surrounding the inner ear, was enlarged. Similar features in living snakes help them detect vibrations.

The animal also had an unusually thick skull. Researchers believe it may have dug through soil by pushing and butting its head against the ground, allowing it to create or move through underground passages.

Together, these features provide the strongest physical evidence yet of a specialized burrowing snake from this early period.

Early Snakes Were More Diverse Than Scientists Thought

Scientists still do not know exactly where the first snakes evolved. Estimates place the origins of snake ancestors at roughly 160 million years ago, while the earliest known possible ancestor dates to around 167 million years ago.

One long-running theory suggests that snakes evolved underground. Another once proposed that they originated in the sea. Fossil discoveries have complicated both ideas because ancient snakes have been found in several different environments.

The new Brazilian fossil does not prove that the first snakes originated underground. Instead, it shows that by 85 million to 75 million years ago, at least one snake lineage had already developed strong adaptations for a life of burrowing.

By the Cretaceous Period, snakes had spread into very different habitats. Some lived on land, others entered aquatic environments, and T. mirim appears to have specialized in moving underground.

Michael Caldwell, a paleontologist at the University of Alberta who was not involved in the new research, told Science News that the finding points to a much more complicated early history for snakes. Their evolutionary family tree likely contained numerous branches whose members developed different bodies and ways of life.

How Snakes Lost Their Legs and Conquered New Habitats

The discovery also adds another piece to a much larger puzzle: how snakes transformed from four-legged reptile ancestors into the highly specialized animals seen today.

Scientists estimate that the major transition toward the familiar legless snake body occurred between about 150 million and 125 million years ago. Fossils show that some early snakes still had hind limbs, suggesting that the disappearance of their legs happened gradually over a long period.

Losing limbs may have offered important advantages. A long, narrow body can move efficiently through soil, thick vegetation and other tight spaces where legs could get in the way.

Around 125 million years ago, snakes also underwent major changes in their skulls, spines and feeding abilities. Their skulls became highly flexible, eventually allowing many species to swallow prey much larger than their heads. Their bodies grew longer and developed large numbers of vertebrae, helping them move efficiently across land, through water and into trees.

These changes helped snakes expand into a remarkable range of environments. More than 4,000 living snake species are now known, from tiny burrowing threadsnakes to giant pythons and fully aquatic sea snakes.

Evolutionary biologist Marc Tollis of Northern Arizona University told Live Science that snakes have become remarkably successful despite the apparent limitations associated with having no legs and being unable to chew food.

“Despite their vast taxonomic, morphological, and ecological diversity, snakes are some of the most successful animals,” Tollis told Live Science. “They definitely have superpowers that we would normally associate with the fantasies.”

Why the Rare Fossil Matters

Snake evolution is particularly difficult to reconstruct because their delicate skeletons often break apart after death. When fossils do survive, their skulls are frequently crushed, destroying many of the structures scientists need to understand their senses and behavior.

The intact braincase of Tametara mirim offers something unusually valuable: direct anatomical evidence of how one early snake interacted with its surroundings.

The finding suggests there was no single simple path from the earliest snakes to the species alive today. Different branches appear to have experimented with different environments and developed specialized bodies suited to life on land, underwater and beneath the ground.

Scientists will need more well-preserved fossils to determine exactly when these different lifestyles emerged and whether burrowing played a role in the earliest stages of snake evolution.

“When organisms become highly specialized for a particular environment, they don’t become so in the blink of an eye,” Simões said. “What we have today are the endpoints of a very long evolutionary history.”

The newly discovered fossil now provides a rare glimpse into one part of that history, showing that while dinosaurs still dominated the surface, at least one highly specialized snake lineage had already adapted to a very different world beneath their feet.