Remarkably preserved feathered dinosaur discovered in China reveals new secrets of flying predator evolution

A predatory bird-like dinosaur with four wings discovered in China adds evidence to the idea that flight evolved several times in different dinosaur groups.

The exceptionally well-preserved feathered dinosaur, which has been named Norellraptor barsboldi, was 3 years old when it died and measured just 21 inches (57 centimeters) long. It was found in the Early Cretaceous Jiufotang Formation in northeastern China, which dates to between 145 million and 100 million years ago.

N. barsboldi had the sharply curved predatory teeth and claws you'd expect of a little, generalist predator and was probably eating early mammals, lizards, amphibians and juvenile dinosaurs, said Scott Hartman, a vertebrate paleontologist at the University of Wisconsin-Madison who wasn't involved in the study. "It wouldn't have been attacking any large dinosaurs. That would be like mosquitoes attacking battleships," he told Live Science.

N. barsboldi was a microraptor. Microraptors were close relatives of birds but not their ancestors; birds belong to a neighboring clade called Avialae. Fossils show that both microraptors and early bird-winged animals in the Avialae clade ‪—‬ such as Archaeopteryx, which lived in the Late Jurassic, about 150 million years ago ‪—‬ had feathers. The puzzle has been whether flight originated in an ancestor of both of these groups or if feathers — and potentially flight — evolved more than once.

The description of N. barsboldi by Andrea Cau, a paleontologist at the OPHIS Paleontological Museum and Herpetological Center in Italy, and his colleagues adds evidence to the latter theory. The team's analysis found that around 30% of the 194 anatomical changes identified across microraptor evolution also evolved in the bird lineage. Aside from feathers, these changes included the fusion of bony projections to the ribs that created a rigid torso, forelimb bones that were relatively robust compared with the hind limbs, and an ulna (the primary weight-bearing bone for a wing) that was longer than the humerus.

However, the team's comparisons with other fossils revealed that the order in which these shared features evolved was different in the two groups. They reported the findings Tuesday (Sept. 29) in the journal Nature Communications.

"This demonstrates that microraptors acquired traits convergent with the early evolutionary stages of true birds, albeit through a distinct evolutionary pathway, supporting the hypothesis that flapping flight evolved independently in non-avialan dinosaurs and birds," said Rui Pei, a paleontologist at the Institute of Vertebrate Paleontology and Paleoanthropology at the Chinese Academy of Sciences who wasn't involved in the work.

"I'm very happy that they've come to the conclusion that there were probably independent origins of flight amongst various groups," Hartman said. "I strongly agree with them."

Even though microraptors had four wings, many of their features were similar to those of modern flying birds. Therefore, "it is reasonable to expect that these non-avialan theropods were capable of behaviors comparable to those of modern avian species," Pei told Live Science by email.

Hartman suggested that microraptors might have done a mix of gliding and flapping. "I doubt they could climb trees like a squirrel to gain height because their forelimbs don't have that range of motion," he said. However, they might have been able to take off after running down a slope, and rather than gliding down from trees, they might have leapt from hills or cliffs, Hartman added.

"There are a bunch of features, like a large well-ossified [bony] sternum or breastbone that could allow for larger pectoral muscles, so they probably have a pretty solid downstroke, which is what generates the thrust to keep it going forward," Hartman said.

The hind wings would have been held directly under the body for stabilizing flight, braking and allowing for rapid control of tight turns. "These are clearly little predatory buggers," he said. "If you're leaping onto things or dropping onto things, that kind of control would be pretty important. It's always best to surprise animals by landing where you planned to rather than somewhere you didn't plan to."

It's also possible that the wings had other purposes, such as demonstrating fitness to mates or warming eggs on a nest, he said.