Deep in the Changma Basin of China's Gansu province, paleontologists have uncovered a dinosaur that may explain a decades-long mystery at one of the world's most remarkable fossil sites. The new species, Jian changmaensis, was a four-winged feathered predator roughly the size of a barn owl that likely hunted ancient birds some 110 million years ago, according to a study published in the Annals of Carnegie Museum.
For years, researchers at the site had found clusters of shattered bird bones compressed into pellet-like masses — resembling those produced by modern owls — but they could never identify what predator had left them behind. "Scientists have found these weird, broken-up clusters of bird bones at this site, and we didn't know what made them," said Jingmai O'Connor, associate curator of fossil reptiles at Chicago's Field Museum and senior author of the study. "This new microraptor dinosaur, Jian changmaensis, is our best guess. It's the only dinosaur found at this site that wasn't a bird, it was a carnivore, and it was much bigger than everything else that we've found there."
Jian belonged to a subgroup of dromaeosaurs — the feathered relatives of Velociraptor — known as microraptors. Most microraptors were crow-sized, but Jian was an exception. "Jian is one of the biggest microraptor specimens that has ever been found," O'Connor noted. The fragment of upper arm bone recovered measures about four inches long, suggesting an animal with roughly a four-foot wingspan. Like other microraptors, Jian likely sported long feathers on both its arms and legs, creating the appearance of four wings.
Rather than flying, these dinosaurs probably glided between trees, much like a flying squirrel. "Jian and the other microraptors probably weren't capable of true, powered flight, but they could probably glide like a flying squirrel," O'Connor explained.
The discovery fills a crucial gap in scientists' understanding of the ancient Changma ecosystem, which has yielded more than a hundred bird fossils but until now only a single non-avian dinosaur specimen. "Jian changmaensis reveals that non-avian dinosaurs lived in what is now the Changma Basin, an area famous for its fossil birds," said Matt Lamanna, corresponding author and senior dinosaur researcher at Carnegie Museum of Natural History. "Jian provides critical new insight into the biological history of the Changma region and the ecological context of the ancestors of today's birds."
Beyond solving a paleontological puzzle, the researchers say Jian helps illuminate why birds — the only surviving dinosaurs — thrived while their close relatives went extinct 66 million years ago. "You cannot understand life on the planet today without looking at its origins," O'Connor said. "Birds are arguably the most successful group of land-dwelling vertebrate animals on Earth today. Learning about early birds and their close non-bird dinosaur relatives gives us a better understanding of what made the group of birds that survived so special."
The study was co-authored by researchers from the Gansu Geological Museum, University of Nebraska State Museum, University of California Museum of Paleontology, Gansu Agricultural University, and the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing.