Our fossil is a rare new witness. It comes from roughly 80-million-year-old rock in São Paulo state, Brazil. We named it Tametara mirim, meaning “adorned” and “small” in the local Indigenous language.
(Photo: Agustin Martinelli)
The new fossil of Tametara mirim reframes how we understand snake evolution.
(Photo: Agustin Martinelli)
Life reconstruction of the burrowing stem snake Tametara mirim which lived alongside now-extinct stem-birds and sauropod dinosaurs.
(Illustration: Gabriel Ugueto)
The bones of Tametara show it had the skull of a burrower. CT scan volume-rendered with VGSTUDIO MAX.
(Image: Roy Ebel)
One theory about how snakes evolved suggests lizards went underground, lost their limbs and elongated their bodies.
(Illustration supplied - Roy Ebel)
80‑million‑year‑old snake fossil sheds light on why lizards lost their limbs and started slithering
Snakes are everywhere in our legends and mythology. Yet for most of us, our blood runs cold whenever we encounter these strangely undulating, scaly tubes of muscle slithering through the leaf litter.
The loss of an arm or leg poses a challenge. Yet snakes do perfectly well without all four of them. This makes them suspect. It also leaves us unable to fathom how this radical transition produced one of the most successful vertebrate body plans.
More than 4,000 species of snakes are alive today, on every continent except Antarctica, from thread-thin burrowers to massive pythons, on land and in the sea. We have studied them since antiquity, and still the oldest question about them has no answer: what turned snakes into snakes?
We have long suspected their peculiar, limbless body plan is explained by how the earliest snakes lived. In a new study, published today in Nature, my colleagues and I describe a small, exquisitely preserved fossil that brings us closer to an answer than ever before.
By Roy Ebel
Research Officer Herpetology, Museums Victoria Research Institute, Australia
The Conversation - July 23, 2026
Snakes lost their limbs millions of years ago to become undulating, scaly tubes of muscles. Scientists are finally figuring out why.
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Fig. 1: Holotype (MPM 420) of T. mirim.
a, Photograph of the whole specimen with the articulated skull and postcranium in dorsal view. Ant, anterior; Bl, block number; Ce.V., cervical vertebrae; Do.V., dorsal vertebrae; Post, posterior; Sk, skull. b,c, Photographs of the skull in lateral (b) and dorsal (c) view. CB, compound bone; F, frontal; Oto, otoccipital; P, parietal; PFr, postfrontal; Pro, prootic; Ptg, pterygoid; Q, quadrate; Soc, supraoccipital; St, supratemporal. d–g, 3D renderings of an anterior precloacal (‘cervical’) vertebra in lateral (d) and anterolateral (e) views, and mid-precloacal (‘dorsal’) vertebra in dorsal (f) and left lateral (g) views. h–j, 3D renderings of the skull in the right lateral view (h) and with exposed brain endocasts in the right lateral (i) and dorsal (j) views. Mes., mesencephalon; Rho., rhombencephalon; Tel., telencephalon. Scale bars, 100 mm (a), 5 mm (b,c,h–j) and 1 mm (d–g). Specimen photos were taken by A.S.H.
Exceptional brain and ecological diversity in the earliest snakes
Understanding the ecological origin of snakes has remained a century-old challenge, hindered by an extremely sparse early fossil record and conflicting interpretations of fossil ecologies.
Here we describe an exceptionally preserved Cretaceous fossil snake, Tametara mirim gen. et sp. nov., from Brazil, representing one of the earliest-diverging stem snakes. High-resolution micro-CT scans reveal unprecedented details of cranial nerves, inner ear and brain anatomy, enabling the most integrated reconstruction of stem snake neuroanatomy to date. Quantitative and qualitative endocast analyses demonstrate that Tametara had a brain morphology distinct from both other stem and extant snakes, revealing substantial early neuroanatomical disparity — and probably sensory functions — in snake evolution. Independent evidence from telencephalon shape and bone microstructure converges on a fossorial lifestyle for Tametara and non-fossorial for another stem snake: Dinilysia.
These results indicate that major ecological transitions occurred early in snake evolution, and that known stem species do not represent the ancestral condition of crown snakes. Early snake evolution thus involved complex shifts in habitat use and sensory ecology, revealing greater ecological and neuroanatomical diversity than previously thought.
By Tiago R. Simões, Gabriela Sobral, Simone Macri, Roy Ebel, Thiago S. Fachini, Augustin G. Martinelli, William R. Nava, Giovanna M. X. Paixão, Luis M. Chiappe, Nicolas Di-Poï & Annie S. Hsiou
Nature - 22 July 2026
A well-preserved fossil snake from the Late Cretaceous of Brazil shows early ecological and brain shape disparity in the group.
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