Ancient Alligator Relative Lived Right After Dinosaur-Killing Asteroid

Paleontologists have identified a new species of extinct alligatorid that lived in what is now Colorado just a few hundred thousand years after the asteroid impact that wiped out the non-avian dinosaurs.

The skull of Mandrasuchus milleri , a species of alligatorid that lived nearly 65.4 million years ago in what is now Colorado, the United States. Image credit: Lessner et al ., doi: 10.1080/02724634.2026.2712566.

The newly identified species lived during the earliest Paleocene, between roughly 200,000 and 350,000 years after the end-Cretaceous mass extinction.

Named Mandrasuchus milleri , it is the earliest confirmed member of Alligatorinae, the subfamily that includes modern alligators.

“Among crocodyliforms, Alligatoroidea is the only group to increase in diversity immediately following the Cretaceous-Paleogene mass extinction event,” said first author Dr. Emily Lessner from Bureau of Land Management and her colleagues.