A Four-Winged Dinosaur from China Reveals How Evolution ‘Invented’ Flight Twice

Did birds and winged dinosaurs learn to fly from the same ancestor?

A newly discovered four-winged dinosaur from China suggests that dinosaur wings evolved twice independently in different dinosaur groups—using different routes to reach similar flight adaptations.

The dinosaur belongs to a group called microraptorines, small feathered predators that were close relatives of birds but followed a separate evolutionary path. Earlier fossils have shown that microraptorines and early birds developed several similar features linked to flight, but many aspects remained unclear.

“The evolutionary relationships between the flight apparatus of birds and the purported aerial adaptations of the microraptorines are controversial from both functional and phylogenetic perspectives,” the researchers note in their study.

The similarities between the two groups make it difficult to tell whether they (microraptorines and birds) inherited the beginnings of flight from the same ancestor or evolved similar flight adaptations independently. 

The new findings may reveal the answer to this question.

A four-winged dinosaur holds the clue

The fossil belongs to a newly described species called Norellraptor barsboldi, a small predatory dinosaur found in the Lower Cretaceous Jiufotang Formation in western Liaoning, China. Its nearly complete skeleton measures 57 centimeters (21 inches), and traces of feathers remain around its forelimbs, hindlimbs, and tail.

Several microraptorines had long feathers on both their forelimbs and hindlimbs, giving them four wings and raising the possibility that they were capable of some form of aerial locomotion.

The exceptional preservation of Norellraptor gave the researchers an unusually detailed look at a microraptorine. They also examined the microscopic structure of its left radius, one of the two long bones in its forearm, to determine its developmental stage.

The bone evidence, together with the fusion and surface features of other limb bones, indicates that Norellraptor was at least three years old when it died and had passed the juvenile stage. 

×

Get smarter every day...

Stay ahead with ZME Science and subscribe.

Daily Newsletter
The science you need to know, every weekday.

Weekly Newsletter
A week in science, all in one place. Sends every Sunday.
No spam, ever. Unsubscribe anytime. Review our Privacy Policy.

Thank you! One more thing...

Please check your inbox and confirm your subscription.

This is an important detail because growth can change the appearance of bones, complicating comparisons between immature and mature dinosaurs.

The researchers then used an evolutionary analysis to compare Norellraptor with other microraptorines, birds, and related dinosaurs to reconstruct how their flight-related features evolved. 

Across the microraptorine lineage, they identified 194 evolutionary changes, and about 30 percent of the traits that characterized microraptorines also evolved independently along the bird lineage.

RelatedPosts

Puffins in trouble as numbers dwindle
Ancient wasps used to grow inside rotting dinosaur eggs
The Two Million Years Rain Crisis That Helped the Dinosaurs Take Over
Women Rate Women’s Looks Higher Than Even Men

The similarities included increasingly robust forelimbs, changes involving the ribs and sternum, a relatively long ulna compared with the humerus, and the appearance of alular feathers—small feathers on the thumb that are also found in modern birds.

At first, this could seem like evidence for a common flight blueprint. If two groups evolved many of the same features, perhaps their common ancestor already possessed the beginnings of that system.

However, when the researchers reconstructed the sequence in which these flight-related changes appeared, they found something more revealing.

Same destination, different evolutionary route

The features did not emerge in the same order in microraptorines and birds. For example, microraptorines first evolved shorter finger bones, a change that may have reduced the hand’s grasping function. 

Later, they evolved other flight-related changes, including a more elongated sternum and fused wrist-and-hand bones. In early birds, the order was reversed. Those latter changes appeared earlier, before the shortening of the finger bones.

“Despite several flight-related adaptations shared by Avialae and Microraptorine, the evolutionary sequences reconstructing the acquisition of those features among the two clades did not follow a common pattern, and thus could not be considered the expression of a shared developmental regime,” the study authors said.

Imagine two engineers independently building similar aircraft. Finding that both machines eventually have the same wing shape and other aerodynamic features would not necessarily mean they copied the same design. 

If they added those components in different sequences, it would strengthen the case that each engineer solved the same problem independently. The researchers argue that something similar happened in these dinosaurs.

“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,” Rui Pei, an expert in paleontology from the Chinese Academy of Sciences who wasn’t involved in the study, told Live Science. 

Flight may have been assembled more than once

The study adds evidence to a provocative possibility that evolution may have fostered the dinosaur wing twice. This doesn’t mean scientists now know exactly how microraptorines flew, or that the fossil proves they possessed the same powered flight used by modern birds.

Their four-wing arrangement was fundamentally different, and researchers still debate whether they mainly glided, flapped, or combined both forms of movement. If they were truly capable of powered flight, their hind wings could have helped microraptorines stay stable in the air, slow down, and make sharp turns.

The animals’ large, well-developed breastbone could also have supported relatively large flight muscles, potentially helping produce a strong downward wing stroke and generate thrust.

The authors conclude that their findings “dismiss a shared developmental pattern driving the evolution of the flying dinosaurs and support multiple and independent selective regimes at the origin of the winged taxa in Paraves.”

Still, Norellraptor represents one branch of a much larger evolutionary experiment. More fossils and additional evidence from bone growth will be needed to determine whether this pattern of independently assembled flight-related adaptations was widespread among bird-like dinosaurs.

If other paravian groups show the same pattern, it would strengthen the idea that flight was not a single biological innovation passed down through the dinosaur family tree. Instead, evolution may have repeatedly tackled the same problem—and arrived at similar flight adaptations through different pathways.

The study is published in the journal Nature Communications.