The Resilience of Xantusiid Night Lizards: Survivors of the Chicxulub Asteroid Collision
A yellow-spotted tropical night lizard (Lepidophyma flavimaculatum)
Dante Fenolio/SCIENCE PHOTO LIBRARY
A small, mysterious group of lizards known as xantusiid night lizards may have been the sole terrestrial vertebrates to survive in the aftermath of the catastrophic Chicxulub asteroid collision, which led to the extinction of the non-avian dinosaurs.
Research conducted by Chase Brownstein and his team at Yale University suggests that these ancient xantusiid night lizards have been around for tens of millions of years, with their lineage possibly originating during the Cretaceous Period, over 66 million years ago.
The Cretaceous Period ended abruptly with a massive asteroid impact near the Yucatán peninsula, causing widespread devastation and wiping out numerous species worldwide. Despite this cataclysmic event, xantusiid night lizards managed to survive and thrive in regions like Cuba, Central America, and the south-western United States.
By analyzing DNA sequences and skeletal anatomy of living and fossil xantusiid night lizards, Brownstein’s team determined that the common ancestor of these lizards emerged over 93 million years ago, deep within the Cretaceous Period. Their reproductive strategy of producing only one or two offspring per clutch may have contributed to their survival during the asteroid impact.
According to Brownstein, the distribution of xantusiid night lizards appears to encircle the impact site of the asteroid, suggesting that ancient populations may have been closer to the event than their modern descendants. Fossil evidence indicates that these lizards did not simply recolonize the region post-impact but were likely inhabitants of North America before and after the catastrophic event.
Many xantusiid night lizard species inhabit rock crevices and possess slow metabolisms akin to other survivors of mass extinctions, such as turtles and crocodiles. This may have enabled them to seek shelter during the impact and its aftermath, contributing to their resilience.
Nathan Lo of the University of Sydney commends the remarkable survival of these lizards in the vicinity of the asteroid impact, noting their ability to endure despite not fitting the typical profile of extinction survivors. While most survivors are small, fast-reproducing species with large geographic ranges, xantusiid night lizards defy these norms by reproducing slowly and having relatively restricted ranges.
