In dense Chinese forests populated by dinosaurs 160 million years ago, two furry critters resembling flying squirrels glided from tree to tree, showing that even in such a perilous neighborhood early mammals had succeeded in going airborne.

Scientists on Wednesday announced the discovery of fossils of two Jurassic Period gliding mammals so well-preserved and complete that they show the wing-like skin membranes the creatures employed while gliding effortlessly between trees.

The two species, Maiopatagium furculiferum from Liaoning Province and Vilevolodon diplomylos unearthed about 40 miles (65 km) away in Hebei Province, come from an extinct early mammalian side branch.