Ancient Burrowing Snake Fossil Illuminates Early Evolution

A fossilized snake named Tametara mirim was recovered from Presidente Prudente, São Paulo, Brazil. The specimen lived 75–85 million years ago in the Late Cretaceous and measured about 17 inches (42 cm). About 60 % of the skull and 70 % of the vertebral column are preserved, including a three-dimensional braincase only 20 mm long. Its preservation places it among just four Cretaceous snakes known with comparable detail.

Reuters

Snakes are thought to have diverged from lizard ancestors roughly 170 million years ago in the Jurassic, but well-preserved Jurassic specimens are absent and Cretaceous material is scarce. Prior finds have shown snakes adapting to burrowing, ground-dwelling, and marine niches. The Tametara specimen provides concrete evidence that fossorial habits were present early in snake evolution, indicating a broader range of habitats than previously recognized.

Reuters

CT scans revealed a brain with relatively small cerebral hemispheres and a reduced optic tectum, features linked to limited reliance on vision. An enlarged otic capsule suggests heightened sensitivity to vibrations, a common trait in underground foragers. The skull’s thickness and inferred robust hindlimbs—similar to those of Najash rionegrina—imply that early snakes retained functional rear limbs while adopting a burrowing lifestyle. Comparison with Dinilysia patagonica shows markedly different brain morphology, underscoring early neuroanatomical diversity.

Reuters

Tiago Simões, lead author of the study published in *Nature* (reported July 22), argues that the ancestral snake was likely a transitional form inhabiting both fossorial and surface environments rather than a specialist. He suggests that multiple, independent ecological incursions shaped snake diversification over millions of years. Michael Caldwell, a paleontologist at the University of Alberta not involved in the research, notes that the finding supports the view that early snake lineages were already branching into distinct anatomical and ecological niches.

Science News

• “Snakes represent one of the most extreme body plans among all vertebrates — animals with a backbone. Understanding the origin of this peculiar and yet highly diverse group remains one of the biggest mysteries in vertebrate evolution,” — Tiago Simões

Reuters

• “Tametara enters a highly selective hall of spectacularly preserved Cretaceous snakes, with only four species in total with similar preservation.” — Tiago Simões

Reuters

• “Rather, it was a transitional one, lying in the interface of fossorial and ground-dwelling environments," Simões said.” — Tiago Simões

Reuters