About 120 million years ago in what is now northwestern China, many kinds of birds flocked to a lakeside ecosystem. This dense avian population would have offered a smorgasbord for a small and opportunistic carnivorous dinosaur. Researchers have now discovered fossils of a dinosaur that seems to fit the bill.
Scientists said they unearthed bones of a Cretaceous Period dinosaur about the size of a barn owl that was closely related to Velociraptor. The dinosaur, named Jian changmaensis, probably was covered with feathers, lived on the ground and in trees, and may have been able to glide like a flying squirrel in ambush attacks against prey, they said.
"Jian would look like a small Velociraptor - the real Velociraptor, not the scaly thing in 'Jurassic Park' - but with long feathers on both the forelimbs and hindlimbs instead of just the former," said paleontologist Matt Lamanna of Carnegie Museum of Natural History in Pittsburgh, one of the leaders of the study published in the journal Annals of Carnegie Museum.
"I often describe Jian as a Velociraptor trying to be a flying squirrel - except, of course, that Jian was predatory and flying squirrels aren't," Lamanna said.
Jian's bones were found at a fossil locality in China's Gansu Province known for its wealth of nicely preserved bird remains. Some of these fossils were broken bones crushed into pellets that resemble those coughed up by present-day owls after they have eaten prey like mice. The researchers suspect that Jian did something similar after eating birds.
"Jian is of the correct size and suspected ecology to have been the 'pellet maker,'" Lamanna said.
Jian, named after a flying creature in Chinese mythology, is known from five shoulder and arm bones that are sufficiently different from Microraptor, a close relative that lived in China at roughly the same time, to show they were distinct species.
While the remains of Jian are too incomplete to show its broader anatomy, the researchers believe it resembled Microraptor, which had feather-covered arms and legs that gave the appearance of four wings.
All meat-eating dinosaurs belong to a group called theropods. Not all were enormous like Tyrannosaurus or Spinosaurus. There were many smaller ones that may have filled the same type of ecological niche as a weasel or wolverine today.
Birds evolved from small feathered dinosaurs during the Jurassic Period. The earliest-known bird, Archaeopteryx, dates to about 150 million years ago.
There would have been plenty of birds around to keep Jian well fed, including the pigeon-sized semi-aquatic Gansus, which likely had webbed feet and, like Archaeopteryx, possessed a mouthful of teeth. Some of the other birds known from this ecosystem are Feitianius, Changmaornis, Avimaia, Novavis and Meemannavis.
"Jian was probably an ambush predator, stalking and pouncing on distracted birds that were working on finding their own meals," said paleontologist Jingmai O'Connor of the Field Museum in Chicago, also one of the study leaders.
"We know Microraptor was an opportunistic predator that fed on birds as well as lizards, mammals and even fish. Jian was likely the same, eating whatever it could catch. Dense bird populations may also have been seasonal, forcing Jian to have a diverse diet," O'Connor said.
Velociraptor was about the size of a large turkey - much smaller than portrayed in films like "Jurassic Park." It lived in Asia about 45 million years after Jian. Velociraptor, Jian and Microraptor are part of a larger group called dromaeosaurs, informally called raptors, with bodies adapted for speed and tenacity.
Perhaps the largest of the raptors was Utahraptor, which lived in North America about 15 million years before Jian appeared in China, and reached up to about 23 feet (7 meters) long. Jian would have been a bit more than 3 feet (1 meter) long, including its tail.
Referring to a lineage within the raptors that includes Jian and Microraptor, Lamanna said, "They're extraordinarily closely related to the earliest birds such as Archaeopteryx - really, just about as close as you can be to being a bird without actually being a bird yourself."
