A recent study confirms that the remains of two new prehistoric mammal species have been found in China. Paleontologists say the two newly discovered species that lived 160 million years ago were the ancestors of modern mammals, and lived in treetops and underground burrows when dinosaurs were roaming across the land.

Ancient Shrew-Like Mammals Outlived Dinosaurs: Study

Agilodocodon scansorius and Docofossor brachydactylus were described in two papers published in the academic journal Science on Friday. The papers note that these remains represent the earliest known examples of arboreal and subterranean mammals. Both species were small, shrew-sized creatures between three and four inches long.

The study highlighted that each species features unique adaptations for their specific, secluded habitats, which helped them survive in the age of the dinosaurs.

Statement from study coauthor

“It’s amazing that these arboreal adaptions occurred so early in the history of mammals and shows that at least some extinct mammalian relatives exploited evolutionarily significant herbivorous niches, long before true mammals,” commented University of Chicago graduate student David Grossnickle, a co-author of the study on Agilodocodon, in a statement Friday.

More on the mammals that outlived dinosaurs

Agilodocodon was a tree-dwelling mammal that had curved horny claws to help it climb and broad front teeth perfect for gnawing bark. Its limb and joints are quite similar to those of modern animals that live in trees or bushes, and its teeth resemble those of modern sap-eating monkeys.

Docofossor lived underground. A short creature with stumpy legs and wide, shovel-like fingers, it was perfectly adapted for digging and life underground. It was physically very similar to the modern African golden mole (a small fluffy creature with a pink nose and stumpy legs), noted Zhe-Xi Luo, a University of Chicago professor and co-author of both studies. Of note, the shared traits between the two species are so similar that researchers think the same genes may be responsible, despite Docofossor and the golden mole emerging from different branches of the mammal family tree.