Study reveals early snakes had diverse brains and ecologies

A new study published in Nature reveals that the earliest snakes exhibited a surprising diversity in brain shape and ecology, challenging long-held assumptions about snake evolution. Researchers analyzed CT scans of fossilized skulls from four ancient snake species that lived between 100 and 70 million years ago, during the Cretaceous period. The findings show that these early snakes already had distinct brain morphologies suited to different lifestyles, including burrowing, aquatic, and terrestrial habitats.

The study affects our understanding of snake origins, suggesting that the common ancestor of all snakes may have been more ecologically varied than previously thought. This matters because it reshapes the narrative of snake evolution, indicating that key adaptations like venom and constriction may have emerged later than the diversification of brain and sensory systems. The research team, led by scientists from the University of Alberta and the University of Bristol, used high-resolution CT scanning to reconstruct the braincases of the fossils, which included species from South America, Africa, and Europe.

Specific numbers and dates from the study include the four fossil species: Dinilysia patagonica (85 million years old), Najash rionegrina (95 million years), and two unnamed species from the Cenomanian stage (100 million years ago). The scans revealed that Dinilysia had a brain adapted for burrowing, while Najash showed features associated with surface-dwelling. The researchers also noted that the brain-to-body size ratio in these early snakes was comparable to that of modern snakes, indicating that brain size evolved early.

Background from the source notes that previous theories suggested snakes evolved from a burrowing ancestor with a simple brain, but the new evidence points to a more complex early history. The study's lead author, Dr. Hongyu Yi, stated that the findings "overturn the idea that early snakes were all similar in brain shape." The likely next steps include further analysis of additional fossils to trace how snake brains evolved over time, and integrating this data with genetic studies to refine the snake evolutionary tree.