These Tiny Night Lizards Survived the Asteroid That Killed the Dinosaurs

When a 7.5-mile-wide asteroid slammed into Earth 66 million years ago, it wiped out nearly everything in its path, including about 75 percent of all species on the planet. But somehow, a group of tiny, slow-moving reptiles managed to survive the blast, despite living so close they could have seen it happen.

According to a new study published in Biology Letters, night lizards—members of the family Xantusiidae—were living right around the Gulf of Mexico at the time of the Chicxulub impact. The asteroid struck what’s now the Yucatán Peninsula, unleashing a wave of firestorms, darkness, and collapse. 

And yet, at least two night lizard lineages made it through. “They would have been all around the margin of the asteroid impact,” study author Chase Brownstein, an evolutionary biologist at Yale, told Live Science. “It’s almost as if xantusiid distribution sketches a circle around the impact site.”

That makes night lizards the only known land vertebrate family to have survived the extinction while living so close to ground zero—and still be found in the same region today. The researchers used DNA sequence data to trace the lizards’ evolutionary history and found their most recent common ancestor lived over 92 million years ago, long before the asteroid struck.

Fossil evidence supports the story. “The fossil record of xantusiids is pretty much fairly continuous on either side of the boundary layer marking the impact,” Brownstein told New Scientist.

Why they survived remains a mystery. Most species that bounce back after mass extinction events tend to reproduce rapidly and spread out. Night lizards don’t. They have slow metabolisms, tiny litter sizes, and small geographic ranges—traits that should’ve made them vulnerable.

“The problem is that [other animals] just aren’t there anymore,” Brownstein said. “What’s interesting is that xantusiids have persisted and have remained endemic to the region.”

The descendants of those survivors are still with us, scattered across the Americas, living much like they always have. They didn’t flee. They adapted.

Their survival complicates what we think we know about extinction. Sometimes, it’s not the fastest or the fiercest that make it; it’s the ones built to outlast.