Bat-winged dinosaur bemuses paleontologists

We thought we were pretty clear on how dinosaurs gradually evolved into birds, developing longer fingers, stronger feathers, and all the rest of that. Now, as Smithsonian Magazine reports, some Chinese fossils are throwing that picture into a little bit of disarray, preserving the remains of dinosaurs with membranous, fuzzy wings like bats:

The first of these dinosaurs, given the adorable moniker Yi qi, was described by paleontologist Xing Xu and colleagues in 2015. While the small dinosaur had a coating of fuzz, its wings were primarily made up of a membrane stretched between the fingers and body. The dinosaur’s wings were more like those of bats, which wouldn’t evolve for more than 100 million years, or like the leathery wings of contemporary flying reptiles called pterosaurs.

Chinese Academy of Sciences paleontologist Min Wang and colleagues have just named a second bat-like dinosaur related to Yi in the journal Nature: Ambopteryx longibrachium.

Ambopteryx differs from its relative in skeletal features, having a longer forelimb than hindlimb and fused vertebrae at the end of the tail that likely supported long feathers, but both represent a family of bat-like dinosaurs that was previously unknown to experts.

“It’s great to see another example of pterosaur-like wings in a scansoriopterygid,” says Washington University paleontologist Ashley Morhardt. The finding not only reinforces the case that such dinosaurs existed, but “paleontologists can now draw stronger biomechanical parallels between the wings of these dinosaurs and those of pterosaurs.”

Paleontologists are not sure exactly what these little dinosaurs were doing with their wings, however. “Ambopteryx and Yi were less likely to be capable of flapping flight,” Wang says. The dinosaurs may have been gliders, similar to flying squirrels of modern forests.

Additional studies could help reveal how these dinosaurs moved and any similarities to the flapping of early birds, Morhardt says. The brain anatomies of airborne dinosaurs, for example, can show specific functions related to flying, but unfortunately the little bat-like dinosaur specimens have been somewhat smooshed over geologic time. “Sadly, like many similar fossils, the skulls of Yi and Ambopteryx appear to be flattened like pancakes due to the pressure and time,” Morhardt says, making it impossible to get a good look at their brains.

Pictures aplenty at the link. (They were cute little guys.)