Overview
- The study published in Nature on July 22, 2026 formally names Tametara mirim (holotype MPM 420) from Brazil’s Adamantina Formation and describes an exceptionally preserved three‑dimensional skull and partial skeleton.
- High‑resolution micro‑CT reconstructions of the brain cavity and analysis of skull bone microstructure independently show reduced visual centers, an enlarged otic capsule, and a thickened skull roof consistent with specialised head‑first burrowing.
- About 60% of the skull and 70% of the vertebral column are preserved, but the fossil lacks teeth and the hip region, so diet, venom status, and direct evidence of hindlimbs remain unresolved.
- Comparisons with another Cretaceous stem snake show large early differences in brain and inner‑ear anatomy, supporting the idea that early snake lineages separately adapted to burrowing, surface living and marine habits.
- Tametara is one of only about four three‑dimensional Cretaceous snake fossils, making micro‑CT endocasts and bone microstructure analyses crucial tools for tracing sensory evolution and prompting a search for more intact braincases to test evolutionary pathways.