Fossil reveals bizarre gliding creature that hunted birds 120 million years ago

BEIJING — A 120 million-year-old fossil found in what's now northwestern China is changing how scientists think about an unusual group of predatory dinosaurs known as microraptors.

The location where the fossil was unearthed adds to the known geographical range of the smaller, gliding cousin of the sickle-clawed velociraptor. The bones also represent the most recent definitive microraptor specimen in the fossil record, expanding the timeline for how long the feathered dinosaurs existed.

A new analysis of the intact shoulder and forelimb bones, first mentioned in a study abstract in 2010, showed the fossil belonged to a previously unknown microraptor species. The research team has named the dinosaur Jian changmaensis, according to the study published Thursday in the journal Annals of Carnegie Museum.

Jian references a one-winged bird in Chinese mythology as a nod to the dinosaur's birdlike characteristics. The species name was also a nod to the Changma Basin in Gansu province, where the fossil was uncovered — and so far, it's the only microraptor specimen to be found outside northeastern China.

"Jian changmaensis reveals that non-avian dinosaurs lived in what is now the Changma Basin, an area famous for its fossil birds," said study coauthor Dr. Matt Lamanna, senior dinosaur researcher and Mary R. Dawson Curator of Vertebrate Paleontology at the Carnegie Museum of Natural History in Pittsburgh, in a statement.

"Our team has recovered more than one hundred bird fossils at Changma, but only this single non-avian dinosaur specimen. Jian provides critical new information on the biological history of the Changma region and the ecological context of the ancestors of today's birds."

The well-preserved fossil could help researchers understand better how microraptors used their wings to move between trees — offering new clues about the origins of avian flight, according to Lamanna.

A gliding predator

At first glance, artist reconstructions of microraptors look like a depiction of birds.

"If you saw that thing sitting in a tree, you wouldn't think velociraptor from 'Jurassic Park,'" Lamanna told CNN. "This is an extraordinarily birdlike dinosaur that could take to the air to some degree."

Feathers covered a microraptor's body — perhaps even more feathers than a bird's because, in addition to their arms or "wings," the dinosaurs also had long feathers on their hind legs, giving the appearance of four wings.

"That's led many paleontologists to suggest that these things probably lived on the ground some but probably could climb and glided from tree to tree, almost like a modern flying squirrel," Lamanna said.

The smallest microraptors were similar in size to modern crows. Jian changmaensis was likely the size of a barn owl. Other fossils that might belong to the microraptor genus hint that these creatures could have reached larger sizes, which suggests that Jian changmaensis was somewhere in the middle.

Velociraptors and microraptors were not birds, but they were closely related to ancestors of the earliest birds, such as Archaeopteryx. The line separating dinosaurs and early birds becomes blurrier as more discoveries are made, Lamanna said, especially as fossils show characteristics of birdlike dinosaurs, or dinosaur-like birds. Modern birds remain the closest living relatives of the dinosaurs, which went extinct about 66 million years ago after a massive asteroid struck Earth.

"They're all dinosaurs in an evolutionary sense, but it really depends on which side of Archaeopteryx you fall," Lamanna said.

For Jian changmaensis's fossil, the dead giveaway that the wing belonged to a microraptor rather than an ancient bird, like so many others at the Changma Basin, was a distinctive feature in the coracoid, a component of the shoulder structure.

The supracoracoid fenestra is a large hole that nearly bisects the shoulder bone. The feature is something all microraptors possess but almost no other creature has, Lamanna said.

The purpose of this hole remains an open question for researchers; Lamanna said he believes it might be related to flight. Like modern birds, microraptors had long shoulder bones. Jian changmaensis has an exceptionally long one.

"It could have something to do with gliding or something about animals that are on the line to birds changing their shoulder structure to become more suited to flight effectively," Lamanna said.

The fossil is only made up of a few bones, but the length indicates that the dinosaur was likely a flier, said Steve Brusatte, a professor of paleontology and evolution at Scotland's University of Edinburgh.

Brusatte was not involved in the study.

"This is neat, a new fossil of those dinosaurs that were basically on the cusp of becoming true birds," Brusatte said.

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