How a mass extinction resulted in the rise of the snakes

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The doom of the dinosaurs was good news for snakes. According to new researchSnake biodiversity began to increase shortly after the Cretaceous-Paleogene mass extinction—you know, brought about by a giant asteroid impact 66 million years ago. The asteroid caused the extinction of about 75 percent of all species and of all non-avian dinosaurs.

But the impact gave primitive snake species the opportunity and space to flourish, and they did. Currently, there are about 4,000 species of elongated, legless reptiles. To study this evolutionary change, a team of researchers examined the diets of extant snake species to get a glimpse into the past. “After the K-PG extinction, [snakes] “Just went through this massive ecological explosion,” Michael Grundler, one of the paper’s authors and a post-doctoral researcher at the University of California Los Angeles, told Ars.

rare fossils


As it turns out, snake fossils are hard to come by. It is rare to find any great snakes because their bodies are loosely articulated and can quickly become fragmented. “They’re really rare in the fossil record. And when we see them in the fossil record, it’s usually just a bit of a vertebrate, often not really a skull, so we can’t get a sense of their ecology.” are,” Grundler said. “It’s nothing like a large mammal or a large dinosaur that has four limbs and the bones are very strong. With snakes, you have all these delicate vertebrae … their skulls are also very loose.”

Because of this, the team behind the new research resorted to making comparisons between existing species. The researchers looked at dietary information from 882 living snake species—often kept in museum collections—and applied mathematical models to reconstruct the diets of their ancestors. This may make it difficult to learn anything about the ancestors of snakes millions of years ago, but Grundler said that, as long as we have good data on living species and their evolutionary relationships, it is possible to trace back their line of descent. .

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According to the researchers’ model, the most likely common ancestor for all extant snake species was an insectivore. Before the mass extinction, there were probably snakes that ate rodents and other animals. After the asteroid hit, however, whether those animals died out is still uncertain, Grundler said. “What we get from the model is the best guess,” he said.

(somewhere forward and backward also a common ancestor between snakes and other types of reptiles, but how it looked and behaved is still debated, he said.)

ancient history

After the extinction, the remaining snakes flourished and diversified into many different species. This is possible because in the wake of the impact, many places were left open. Similarly, there were even smaller vertebrate critters like birds to hunt. But with the diversification of snakes, the diversity of diet increased—sometimes they eat crazy big things. like an antelope. “Modern snakes have a huge, surprising variety of diets,” Grundler said. “They all evolved that diversity from a single ancestor.”

The research also shows that the increase in snake biodiversity slowed for most species of snakes as they settled into their new habitats. However, species arriving at new locations continued to adapt in different ways.

According to Grundler, this research could help us understand how lineages react to ecological opportunities. It also adds to the body of research surrounding the ecological history of snakes; another paper Published in September shows similar findings. “It also speaks to the importance of our natural history museums and to collecting data on animals in nature,” he said.

PLOS Biology, 2021. DOI: 10.1371/journal.pbio.3001414 (About DOI)

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