How Tiny Night Lizards Witnessed the Asteroid Strike That Ended the Dinosaurs—and Survived!

A fascinating new study reveals that night lizards, tiny reptiles from the Xantusiidae family, were around during the catastrophic asteroid impact that wiped out the dinosaurs 66 million years ago. Surprisingly, they still inhabit parts of the Gulf of Mexico region today.

Researchers led by Chase Brownstein from Yale University confirmed that these lizards survived the devastating event, which resulted in the loss of about 75% of Earth’s species during the Cretaceous-Paleogene (K-Pg) mass extinction event. The asteroid, estimated to be 7.5 miles wide, struck what is now Mexico’s Yucatán Peninsula, creating a chaotic environment.

So, how did these lizards manage to weather such destruction? While the exact reasons remain a mystery, their slow metabolism might have given them an edge. They wouldn’t need to eat as frequently as other animals, which could explain their survival. In fact, the study suggests that night lizards were likely close enough to witness the impact.

Published in *Biology Letters*, the findings highlight the unique lineage of night lizards. Brownstein and his team did a deep dive into their ancestry, using a method called molecular clock dating. This technique estimates the age of species based on genetic mutations. They found that the most recent common ancestor of modern night lizards appeared around 90 million years ago, long before the asteroid hit.

Interestingly, two main lineages of night lizards weathered the asteroid strike. One lineage evolved into *Xantusia*, which can be found from the southwestern United States into Mexico, and another lineage led to *Cricosaura*, known for the Cuban night lizard (*Cricosaura typica*). Unlike many other species that perished, night lizards have remained tied to North and Central America.

This resilience sets them apart as the only terrestrial vertebrates known to have survived near the impact location. In comparison, other survivors of the K-Pg event included birds, fish, and a few mammals, but they are not endemic to that particular region. Some researchers believe that other reptiles, like certain turtles, might have also survived similarly, yet those lineages eventually vanished.

Brownstein notes the uniqueness of xantusiids: “The problem is that they just aren’t there anymore.” This persistence raises questions about how certain species adapt and survive over millions of years, especially in the face of global catastrophes.

As we reflect on these ancient creatures, it’s essential to consider modern conservation efforts. Species today face their own survival challenges due to climate change, habitat destruction, and pollution. The night lizard’s story reminds us of the resilience of life and the importance of preserving diverse ecosystems for future generations.

For an in-depth look at the study, you can read the full article in *Biology Letters* here.

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