Where did the first snake crawl? The discovery that changes the story of evolution
A new study reveals that the evolution of snakes was much more diverse than previously thought: a fossil discovered in Brazil indicates that as early as 80 million years ago, they inhabited different habitats and developed different sensory strategies.
Snakes are lizards that have undergone significant changes, with more than 4,000 living species today. The origin of snakes has long been one of the most controversial questions in evolutionary biology. However, their sparse fossil record has made it difficult to define the factor that drove the development of their limbless body structure. For decades, scientists have debated whether the elongated, limbless snake body first evolved as an adaptation for burrowing in the ground or for living in water. A study published in the journal Nature challenges this framing: early snakes did not follow a single ecological path, but experimented with multiple habitats and sensory strategies.
"Our findings show that early snakes were characterized by exceptional ecological and morphological diversity by the end of the Cretaceous, about 80 million years ago," said Dr. Nicolas Di-Poi of the Institute of Biotechnology (HiLIFE) at the University of Helsinki, one of the study's authors.
The researchers describe a new species of snake that lived in southeastern Brazil at the end of the Cretaceous, about 80 million years ago. The species, Tametara mirim, is one of the best-preserved fossil snake skeletons known in the world. The team reconstructed the fossil digitally using computed tomography and cinematic 3D rendering, revealing details of the snake's skull, vertebrae, and brain endocast (the internal cavity of the skull) without causing it damage. Dr. Di-Poi, along with Dr. Simone Macri, his colleague at the HiLIFE institute, were responsible for the reconstruction and comparative analysis of the brain anatomy, linking early neuroanatomy to sensory ecology and habitat evolution.
The researchers compared the ancient snake to another fossil, Dinilysia patagonica, discovered in Argentina.
"These two snakes had brain shapes that were strikingly different from each other and from most other snakes studied. The brain shape and bone microstructure pointed to the same conclusion: the species discovered in Brazil was adapted for burrowing in the ground, while the species discovered in Argentina was adapted for life on the ground. Together with evidence from marine sediments, the findings reveal a number of changes in the early evolution of snakes, based on their lifestyle and the habitats in which they lived, much earlier than previously thought," explained Dr. Di-Poi.
According to Dr. Macri, the brain tells a much richer story than the skeleton alone. "By combining CT-based brain reconstructions with data from living snakes, we were able to show that early snakes did not just progress toward one modern state, but experimented with different sensory and ecological strategies. This means that early snakes did not follow a single evolutionary path, but snakes differed from each other in how they sensed their environment," said Dr. Macri.
