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Exceptional brain and ecological diversity in the earliest snakes
Tiago R Simões1, Gabriela Sobral2, Simone Macrì3
1Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, USA. simoes@princeton.edu.
Nature
|July 22, 2026
Summary
A new fossil snake, Tametara mirim, reveals early snake evolution involved significant neuroanatomical and ecological diversity. This discovery challenges previous assumptions about the ancestral snake condition and highlights early habitat shifts.
Area of Science:
- Paleontology
- Evolutionary Biology
- Comparative Anatomy
Background:
- The ecological origins and early evolution of snakes are poorly understood due to a sparse fossil record.
- Previous interpretations of fossil snake ecologies have been conflicting.
Purpose of the Study:
- To describe a new exceptionally preserved Cretaceous fossil snake, Tametara mirim, from Brazil.
- To reconstruct the neuroanatomy and infer the lifestyle of early stem snakes.
- To investigate early neuroanatomical and ecological diversity in snake evolution.
Main Methods:
- High-resolution micro-CT scanning of the fossil snake.
- Detailed reconstruction of cranial nerves, inner ear, and brain anatomy.
- Quantitative and qualitative endocast analyses.
- Analysis of telencephalon shape and bone microstructure.
Main Results:
- Tametara mirim represents one of the earliest-diverging stem snakes with unique brain morphology.
- Neuroanatomical analyses revealed substantial early disparity in snake evolution, suggesting diverse sensory functions.
- Evidence suggests Tametara had a fossorial (burrowing) lifestyle, contrasting with the non-fossorial lifestyle of Dinilysia.
- Major ecological transitions occurred early in snake evolution, with stem species not representing the ancestral crown snake condition.
Conclusions:
- Early snake evolution was characterized by complex shifts in habitat use and sensory ecology.
- The discovery of Tametara mirim indicates greater ecological and neuroanatomical diversity in early snakes than previously recognized.
- Known stem snake species do not reflect the ancestral state of modern snakes, underscoring the complexity of early snake diversification.
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