More than 4,000 snake species live today, but all evolved from heavily modified lizard ancestors. Scientists still do not fully understand how snakes developed their elongated, limbless bodies. Because early snake fossils are rare, identifying the environments and behaviors that influenced snake evolution has remained challenging.
For decades, researchers debated whether snakes first evolved their long, limbless bodies underground or in aquatic environments. New research published in Nature suggests that early snake evolution followed neither a single habitat nor one straightforward path. Instead, ancient snakes occupied diverse environments and developed different sensory and anatomical adaptations.
“Our findings show that early snakes had already achieved remarkable ecological and morphological diversity by the Late Cretaceous, around 80 million years ago,” says lead author Tiago Simões, Assistant Professor at Princeton University.
Exceptionally Preserved Fossil Snake Sheds Light on Evolution
The researchers studied a newly identified snake species from Late Cretaceous deposits in southeastern Brazil. Dating to approximately 80 million years ago, Tametara mirim is represented by one of the most complete fossil snake skeletons ever discovered.
Using computed tomography and cinematic 3D rendering, the research team produced a detailed digital reconstruction of the fossil. The scans revealed important features of the skull, vertebrae and brain endocast that would have been difficult to examine from the exposed bones alone.
Postdoctoral researcher Simone Macrì and Research Director Nicolas Di-Poï, both affiliated with the University of Helsinki’s HiLIFE Helsinki Institute of Life Science, led the reconstruction and comparative analysis of the fossil’s brain anatomy. Their work linked the neuroanatomy of early snakes to their sensory abilities, habitats and evolutionary history.
Fossil Brain Structures Reveal Different Snake Lifestyles
The team compared Tametara mirim with Dinilysia patagonica, another fossil snake discovered in Argentina. The comparison revealed major differences in brain structure, indicating that the two species were adapted to very different lifestyles.
“The two had strikingly different brain shapes, both from each other and from most other snakes studied. Brain shape and bone microstructure pointed to the same conclusion: Tametara was adapted to burrowing, Dinilysia to life on the ground. Together with evidence from marine sediments, the findings reveal several shifts between burrowing, terrestrial and marine lifestyles in early snake evolution. Different lineages explored different habitats much earlier than previously thought,” concludes Research Director Nicolas Di-Poï.
The findings suggest that early snake evolution involved repeated transitions between underground, terrestrial and marine environments. Rather than gradually developing toward one standard body shape or sensory system, separate snake lineages evolved specialized adaptations for different ecological conditions.
“The brain tells a much richer story than the skeleton alone. By combining computed tomography-based brain reconstructions with data from living snakes, we could show that early snakes were not simply progressing toward one modern condition but experimenting with different sensory and ecological strategies. This means that early snakes did not follow a single evolutionary pathway,” says Researcher Simone Macrì.
New Insights Into the Evolution of Snakes
The study was 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, alongside an international team of collaborators. The research provides new evidence that snake evolution was more diverse and adaptable than previously recognized.
Source: www.sciencedaily.com