A new study suggests that all current snakes evolved from a few species that survived the impact of the giant asteroid that wiped out the dinosaurs and most living things at the end of the Cretaceous. The authors indicate that this devastating extinction event was a form of “creative destruction” that, like mammals, allowed snakes to diversify into new niches previously occupied by their competitors.
The research, published in Nature Communications , shows that snakes, which currently include nearly 4,000 living species, began to diversify the moment an extraterrestrial impact wiped out the dinosaurs and most other species that populated the planet.
The researchers analyzed genetic differences between modern snakes and samples from the fossil record to reconstruct the evolution of snakes. Their results show that all current snakes originated from a few species that survived the asteroid impact 66 million years ago, during the same extinction that wiped out the dinosaurs.
Survivors underground
The authors argue that the snakes’ ability to shelter underground and go long periods without food helped them survive the destructive effects of the impact. Following the extinction of their competitors, including Cretaceous snakes and dinosaurs themselves, survivors were able to move to new niches, habitats, and continents.
In this way, the snakes began to diversify and this was the origin of lineages such as snakes, cobras, snakes, pythons and boas, exploiting new habitats and new prey. The diversity of modern snakes, including arboreal snakes, sea snakes, venomous vipers and cobras, and huge constrictors like boas and pythons, emerged only after the extinction of the dinosaurs.
The fossils also show a change in the shape of the snake vertebrae as a consequence of the extinction of the Cretaceous lineages and the appearance of new groups, including giant sea snakes up to ten meters long.
“It is remarkable, because not only are they surviving an extinction that kills so many animals, but in a few million years they are innovating, using their habitats in new ways,” explains lead author and Catherine Klein, researcher at Friedrich-Alexander -Universität Erlangen-Nürnberg (FAU) in Germany.
The study also suggests that snakes began to spread around the world around this time. Although the ancestor of living snakes probably lived somewhere in the southern hemisphere, only after extinction would expansion into Asia occur.
The study also found evidence of a second major diversification event around the time the world went from hot to cold climates that saw the formation of polar ice caps and the onset of the Ice Age. The patterns observed in snakes point to the key role of catastrophes – severe, rapid and global environmental disturbances – as drivers of evolutionary change. “The destruction of biodiversity leaves room for new solutions to emerge and new land masses to settle. Ultimately, life becomes even more diverse than before, ”concludes Nick Longrich, study co-author and researcher at the University of Bath.
Text: University of Bath
