Ancient Brazilian snake Tametara mirim reveals early burrowing lifestyle and brain diversity

Researchers describe Tametara mirim, a well-preserved Late Cretaceous stem snake from Brazil, whose high‑resolution CT scans reveal a distinct brain and inner-ear morphology consistent with fossorial life. Its endocast shows mildly enlarged cerebral hemispheres and a prominent pituitary, while the inner ear exhibits features typical of burrowing snakes, contrasting with coeval Dinilysia, a non‑fossorial stem snake. Phylogenetic analyses place Tametara among the earliest snakes, closely related to Najash, supporting a Middle Jurassic origin for snakes and a Late Cretaceous crown-snake radiation. The study, integrating geometric morphometrics of brain endocasts and bone microstructure, shows substantial early neuroanatomical and ecological disparity, indicating that multiple habitat shifts (fossorial and non‑fossorial) occurred in stem and crown snakes, and that ancestral snakes were ecologically diverse rather than uniform.