In 80 million BCE, an ancient reptile left behind a crucial fossil showing how limbs disappeared. 80 million years later, scientists found it suggested early snakes may have evolved across both land and water

An 80-million-year-old fossil discovered in Brazil is offering a new glimpse into how early snakes evolved from lizard-like ancestors. The tiny fossil belongs to a previously unknown species called Tametara mirim. Its unusual brain anatomy suggests that the earliest snakes may have occupied very different environments, rather than following one simple evolutionary path.

The fossil and its significance are detailed in a study published July 22, 2026, in Nature, titled “Exceptional brain and ecological diversity in the earliest snakes.” [Simões, T.R., Sobral, G., Macrì, S. et al.Exceptional brain and ecological diversity in the earliest snakes.Nature(2026)]

The research team used high-resolution micro-CT scans to reconstruct the brain, inner ear, and other anatomical features of Tametara mirim, providing evidence that early snakes had greater ecological and neuroanatomical diversity than previously recognised.

What did the fossil reveal?

The fossil was discovered in 2020 at a quarry in Brazil’s São Paulo state, in rock dated to between 75 million and 85 million years ago. Researchers identified it as a previously unknown species, Tametara mirim.

The name carries a meaning tied to its appearance and origins. Its genus name refers to the pronounced bone feature on top of its skull, while its species name means “small” in the Tupí-Guaraní language of local Indigenous people.

The specimen itself was small. Around 16.5 inches of its body was preserved, along with a skull measuring about 0.7 inches. Researchers recovered roughly 60 percent of the original skull and about 70 percent of the vertebral column.

High-resolution CT scans allowed scientists to examine the fossil’s brain and inner-ear structures. Because a snake’s brain fits closely inside its skull, these features can provide important clues about how the animal lived.

The scans showed that T. mirim had a poorly developed region associated with vision, an enlarged inner-ear structure commonly seen in burrowing snakes and a thick skull. Together, those characteristics suggest that the animal lived underground.

Were the first snakes land or water dwellers?

For years, researchers have considered three possibilities for where the earliest snakes lived: in water, on land or underground. The new fossil makes that question more complicated. Researchers compared Tametara mirim with Dinilysia patagonica, another early snake discovered in Argentina. D. patagonica lived around 90 million years ago and reached roughly seven feet in length. Its anatomy indicates that it lived on the surface of the land.

The two ancient snakes had strikingly different brain shapes. That difference suggests that early snakes were already displaying substantial neuroanatomical diversity and likely had different sensory abilities.

As evolutionary biologist Roy Ebel writes for the Conversation, “Snakes are essentially highly modified lizards. Sometime in the age of dinosaurs, one lizard lineage lost its limbs and stretched out its body. The key question is why.”

The new evidence does not provide a simple answer to that question. Instead, it suggests that early snake evolution may have involved several lifestyles and environments.

What does this mean for snake evolution?

The study, published July 22 in Nature, points toward a much more complicated early history for snakes than researchers once suspected.

Michael Caldwell, an evolutionary biologist at the University of Alberta who was not involved in the study, tells Science News’ Libby Riddle that early snake evolution was clearly more complicated than previously thought. Rather than a straight progression from one environment to another, the evidence points toward a changing family tree filled with different body forms and ways of life.

That makes Tametara mirim especially important. Its underground adaptations existed alongside the surface-dwelling characteristics seen in Dinilysia patagonica, showing that ancient snakes were not necessarily following one shared lifestyle.

Ebel writes for the Conversation, “We set out to settle the century-old question of what turned snakes into snakes with the firmest reconstruction yet of how the earliest of these reptiles lived.”

“Instead, we may need to reframe the question: It was never simply sea or soil.”




The findings therefore add another piece to the long-running mystery of snake evolution. Rather than revealing one environment where the first snakes developed their distinctive limbless bodies, the fossil suggests that their evolutionary history was already surprisingly diverse.

FAQs

What is Tametara mirim?
It is an 80-million-year-old snake species identified from a fossil discovered in Brazil.

Did early snakes all live in the same habitat?
No. The evidence suggests early snakes occupied different environments, including underground and land-based habitats.