Chinese paleontologists say they have found the remains of a hitherto unknown type of tiny, feathered dinosaur that may have holed up in trees, a finding that may give valuable insights into how birds evolved.
The 124-million-year-old fossil was discovered in Chaoyang county, in western Liaoning, northeastern China, at a rock formation that has been a literal treasure trove, yielding more than a thousand specimens of early birds and feathered dinosaurs.
The creature has been dubbed Microraptor zhaoianus, named after Zhao Xijin, a Chinese dinosaur-hunter who was a father-figure to the leader of the team, Xing Xu, himself an eminent paleontologist.
The find, by a team from the Institute of Vertebrate Paleoanthropology at the Chinese Academy of Sciences, is reported in Thursday's issue of Nature, the British science weekly.
The fossil represents an adult creature about the size of a crow, with a feathery coverage and articulated feet with curved claws similar to those used by perching birds.
Even so, it is a dinosaur and the smallest non-flying member of the theropods -- biped, meat-eaters that strode the planet between 230 million and 66.4 million years ago.
It is classed as a a member of the Dromaeosauridae, or raptors. These were a subgroup of dinosaurs that were smart, small, fast and efficient killers closely related to birds.
Paleontologists are eager to find a link to prove that birds evolved from dinosaurs, an idea that was heatedly contested until the first feathered dinosaur remains were unearthed in Liaoning two years ago.
The earliest identified bird so far is Archaeopteryx, which lived from about 150 million years ago during the Jurassic period, when many dinosaurs lived.
The Xu team do not suggest that Microraptor is that link, but say that its claws suggest the little creature could climb trees.
This, they suggests, strengthens the theory that birds arose from evolutionary pressure.
According to this thinking, small dinosaurs took to the trees, where they were able to escape from predators and find an abundance of insect food.
Over millions of years, by the process of natural selection, they developed grasping feet and enlarged claws to hold on to swaying branches, as well as larger eyes and narrow snouts to provide better forward vision.
They developed internal controls over their temperature -- became warm-blooded -- as this would give them a speed advantage in hunting for insects.
Feathers developed from reptilian scales, possibly to provide insulation to prevent loss of heat or, more directly, to provide flight.
"The discovery of Microraptor provides the first evidence to suggest that some non-avian theropods had arboreal habits," say the team.
"The evidence for arboreality in non-avian therapods is an important discovery, as it could be used to test the 'tree-down' hypothesis for the origin of bird flight.
"The theropod ancestors of birds may have passed through an arboreal phase, although more evidence is needed to confirm this hypothesis" -- PARIS (AFP)
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