80-million-year-old snake brain reveals early habitat shifts

A fossil snake species that lived 80 million years ago has revealed that early snakes experimented with multiple habitats and sensory strategies, not a single evolutionary path. The research, published in Nature on August 5, 2026, examined the exceptionally preserved skull and brain of Tametara mirim from Brazil, showing it was adapted for burrowing, while another fossil snake, Dinilysia patagonica, was suited for life on the ground. The findings challenge the long-standing debate over whether snakes evolved their elongated, limbless bodies underground or in water. Instead, the study suggests that different snake lineages independently shifted between burrowing, terrestrial, and marine environments much earlier than previously thought. The international team, led by Tiago Simões of Princeton University, with senior authors Nicolas Di-Poï of the University of Helsinki and Annie Hsiou of the University of São Paulo, used computed tomography and 3D rendering to reconstruct the brain and inner ear of Tametara mirim. The digital reconstruction, directed by postdoctoral researcher Simone Macrì and Research Director Nicolas Di-Poï at the University of Helsinki's HiLIFE Helsinki Institute of Life Science, showed that Tametara and Dinilysia had strikingly different brain shapes, indicating distinct sensory adaptations. According to the researchers, the brain shape and bone microstructure of Tametara pointed to a burrowing lifestyle, while Dinilysia was adapted to terrestrial life. Together with evidence from marine sediments, the findings reveal several shifts between burrowing, terrestrial, and marine lifestyles in early snake evolution. The study highlights that early snakes were not simply progressing toward one modern condition but were experimenting with different sensory and ecological strategies. The fossil, discovered in Late Cretaceous deposits in southeastern Brazil, is one of the most complete snake skeletons ever found. The research connects the neuroanatomy of early snakes with their sensory abilities, habitats, and evolutionary history, showing that early snakes had already achieved remarkable ecological and morphological diversity by the Late Cretaceous.