This Tiny Creature Survived a World of Dinosaurs and Changed What Came Next

Scientists identified a new hamster-sized Late Cretaceous mammal from Baja California, naming it Cimolodon desosai.

The fossil is unusually complete, including teeth, skull, jaws, and limb bones, which let researchers reconstruct its anatomy and ecology.

As a multituberculate, the species likely had a small body size and an omnivorous diet that may have aided survival through the dinosaur-killing extinction.

The find provides rare skeletal evidence for a mammal lineage that outlasted the end-Cretaceous mass extinction and informs early mammal evolution.