BATH, England — All living snakes evolved from a few survivors of the giant asteroid impact that wiped out the dinosaurs, according to a new study. Researchers say that the devastating impact that killed off most of life on Earth was a form of “creative destruction” that allowed snakes to thrive and diversify into new niches previously filled by their competitors.
The findings suggest that snakes — including almost 4,000 living species today — started to diversify around the time of the asteroid strike.
Scientists at the University of Bath used fossils and analyzed genetic differences between modern snakes to reconstruct snake evolution. The analyses helped to pinpoint the time that modern snakes evolved. They conclude that all living snakes trace back to just a handful of species that survived the asteroid impact 66 million years ago.
“Our research suggests that extinction acted as a form of ‘creative destruction’ — by wiping out old species, it allowed survivors to exploit the gaps in the ecosystem, experimenting with new lifestyles and habitats,” says study corresponding author Dr. Nick Longrich of the University of Bath, in a statement. “This seems to be a general feature of evolution — it’s the periods immediately after major extinctions where we see evolution at its most wildly experimental and innovative. The destruction of biodiversity makes room for new things to emerge and colonize new landmasses. Ultimately life becomes even more diverse than before.”
The research team argues that the ability of snakes to shelter underground and go for long periods without food helped them survive the destructive effects of the impact. In the aftermath, the extinction of their competitors — including Cretaceous snakes and the dinosaurs themselves — allowed snakes to move into new niches, new habitats, and new continents. The team says snakes then began to diversify, producing lineages such as vipers, cobras, garter snakes, pythons, and boas, exploiting new habitats, and new prey.
Modern snake diversity — including tree snakes, sea snakes, venomous vipers and cobras, and huge constrictors such as pythons and boas — emerged only after the dinosaur extinction. Fossil evidence also shows a change in the shape of snake vertebrae in the aftermath, resulting from the extinction of Cretaceous lineages and the appearance of new groups, including giant sea snakes up to 10 meters (32.8 feet) long.
“It’s remarkable, because not only are they surviving an extinction that wipes out so many other animals, but within a few million years they are innovating, using their habitats in new ways,” notes study lead author Dr. Catherine, a recent Bath graduate who now works at Friedrich Alexander University in Germany. She adds that the study also suggests that snakes began to spread around the globe around that time. “Although the ancestor of living snakes probably lived somewhere in the Southern Hemisphere, snakes first appear to have spread to Asia after the extinction,” she says.
The study also shows evidence for a second major diversification event around the time that the world shifted from a warm “greenhouse Earth” into a cold “icehouse” climate, which saw the formation of polar ice caps and the start of the Ice Ages. “The patterns seen in snakes hint at a key role for catastrophes — severe, rapid, and global environmental disruptions — in driving evolutionary change,” said Dr. Klein.
The study is published in the journal Nature Communications.
South West News Service writer Stephen Beech contributed to this report.