February 23, 2024
4 min read
Snakes saw a burst of adaptation about 128 million years ago that led to them exploding in diversity and evolving up to three times faster than lizards
An eyelash pit viper from the New Wold tropics.
Alejandro Arteaga/Khamai Foundation
When they first evolved from lizards more than 100 million years ago, snakes were ecological bit players slithering around the fringes of ecosystems dominated by dinosaurs. But today there are around 4,000 species of snakes, ranging in size from green anacondas that weigh more than adult gorillas to thread snakes that are lighter than a paperclip. They are some of Earth’s most effective and diverse predators. “Snakes are truly exceptional,” says Daniel Rabosky, an evolutionary biologist at the University of Michigan.
Out of roughly 25 groups of lizards that independently lost their legs, snakes became the only one to truly explode in diversity. A new study published this week in Science explains why: genomic data has revealed that snakes experienced a burst of adaptation around 125 million years ago—early on in their evolutionary history—that helped them exploit multiple ecological gaps. “The paper demonstrates that snakes are an evolutionary ‘singularity’ that has changed the face of the Earth,” says Michael Lee, an evolutionary biologist at Flinders University in Australia, who studies reptile evolution but wasn’t involved with the new research.
To determine what set snakes apart from groups of legless lizards, Rabosky and a team of researchers constructed an in-depth evolutionary tree. They shaped its branches by using genomic data from more than 1,000 species of squamates (the order of reptiles that includes snakes and lizards) to chart how these scaly critters changed over time. Finally, they bolstered this dataset with dietary information from nearly 70,000 individual lizards and snakes, primarily specimens preserved in alcohol in museum collections.
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