Scientists have identified two new species of ancient gliding mammals that lived about 160 million years ago, when dinosaurs roamed the Earth. The very well-preserved fossils provide important clues about how diverse prehistoric mammals were. The gliding critters, which resembled today’s flying squirrels, had taken to the sky to possibly escape predatory dinos on the ground.

The new species, described in two papers published today in Nature, belong to an extinct branch of mammals. They’re not the first mammalian gliders known to have lived alongside dinosaurs, but they’re incredibly well preserved, featuring peculiar body characteristics. One species, called Maiopatagium furculiferum, had fossilized a wing membrane and fused wishbones reminiscent of birds, but shoulder girdles that looked like those of platypuses. Its teeth also suggest the animal fed on soft plant parts. The other species, called Vilevolodon diplomylos, had similar molars to modern seed-eating squirrels, suggesting a more seed-based diet.

The first mammals evolved roughly 210 million years ago, according to Reuters, and they were incredibly diverse: ancient mammals were tree climbers, swimmers, burrowers, and gliders. That means the animals covered different ecological niches, just like modern mammals, even if dinosaurs still dominated the landscape. The new species described today add to our knowledge of what some mammal ancestors looked like.

The two new species were unearthed in China, and lived more than 100 million years before bats — today’s only flying mammals — appeared. They probably evolved into gliders to avoid being eaten by ground-roaming predators like large dinosaurs, or to access food high in the trees.

They also show us how much we have left to discover about our planet’s past. “I expect we’re going to keep finding more strange things,” Guillermo Rougier, a paleontologist at the University of Louisville, told The New York Times.