Image: Mick Ellison/American Museum of Natural History

Paleontologists at the American Museum of Natural History in New York, where the fossil on loan from China has gone on display, believe the skeleton of a young dinosaur covered with primitive fluff is proof that the creatures developed feathers for warmth, not flight, and that birds evolved from dinosaurs. Mark Norell, chairman of the division of paleontology, said in a telephone interview that the fossil was about the size of a duck with a long tail. "It shows us that these creatures looked more like weird birds than giant lizards," he said. The 2.5 foot long fossil, described in the journal Nature, was found by farmers in layers of volcanic and sedimentary rock of the Yixian Formation in China's northeastern Liaoning Province.

It is a dromaeosaur - a small, fast-running carnivorous dinosaur with a sickle-like claw on its middle toe. The creature is related to the mighty Tyrannosaurus rex and belongs to a group of dinosaurs called theropods - two-legged predators with sharp teeth. Feathers have been found on dinosaurs which could not fly and which "pre-dated the origins of birds and avian flight," the article in Nature said. Norell said the most reasonable explanation for the feathers was not flight but warmth. "It's conceivable that smaller dinosaurs like this one and even the young of larger species like Tyrannosaurus rex may have needed feathers to keep warm," he said.

Until now most of the fossils of feathered dinosaurs, which were first discovered in 1995, have been incomplete. Scientists opposed to the theory that birds evolved from dinosaurs argued that the partial remains of the fluffy prehistoric creatures were not sufficient enough proof for the hypothesis. They believe birds evolved independently from a still undiscovered reptile. Ji Qiang, of the Chinese Academy of Geological Science which lent the fossil to the New York museum, said the discovery was particularly important because it showed the feathers were attached to the dinosaur's body.

"This is the specimen we've been waiting for. It makes it indisputable that a body covering similar to feathers was present in non-avian dinosaurs," he said in a statement. Theropod dinosaurs and birds share about 100 anatomical features, including a wishbone, swiveling wrists and three forward-pointing toes. Norell said dromaeosaurs were theropod dinosaurs thought to be most closely related to birds.

An exquisitely complete feathered dinosaur has emerged from the famed fossil beds of northeastern China's Liaoning Province. The new discovery, announced today in the journal Nature, gives further weight to the argument that birds evolved from dinosaurs and provides the strongest evidence yet that feathers pre-date the origin of flight.

Earlier finds from Liaoning had hinted at the presence of featherlike structures on several dinosaur specimens, but critics charged that the structures were instead fibers of the protein collagen or that the fossils represented not dinosaurs but flightless birds.

Opponents of the bird-dinosaur connection also noted that no feathers were known from dromeosaurs-a group of small- to medium-size theropod dinosaurs that exhibit numerous traits in common with birds and are therefore widely held to be their closest relatives.

The new fossil, however, appears to answer both of those arguments. Paleontologist Mark Norell of the American Museum of Natural History in New York City and his colleagues report that the 130-million-year-old specimen represents a dromeosaur covered with filamentous structures that exhibit a branching pattern unique to feathers.

The presence of featherlike structures on such a creature indicates that feathers must have evolved for some purpose other than flight-perhaps to help the animal keep warm. Indeed, for modern birds, which are warm-blooded, feathers provide critical insulation. Thus, Norell says, non-avian dinosaurs may have developed primitive feathers as they developed warm-bloodedness.

AMAZING NEW FEATHERED DINOSAUR FOUND IN CHINA

The Smallest Dinosaur Yet Discovered, It May Give Key Insights Into the Evolution of Flight

An interesting and notably tiny new species of dromaeosaurid dinosaur that may give insights into the evolution of flight has been discovered in the Liaoning Province of China, according to paleontologist Xing Xu.

The dinosaur, Microraptor zhaoianus, is also touted as the smallest non-avian dinosaur yet discovered, and may also give key clues to the relationships between dromaeosaurs, troodontids, and modern birds. It was officially named by Xu and two colleagues in the December 7th issue of the journal Nature.

Measuring in at 39 centimeters (nearly 16 inches) and possessing a tail of 24 centimeters, Microraptor was a bipedal dinosaur that may have been adapted to live in trees. A small section of intermentary fuzz, what scientists believe to be the precursor to feathers, was also found on the specimen. Although it lived some 20 million years after Archaeopteryx, the first known bird, Microraptor is being called one of the most-bird like dinosaurs known, and many paleontologists believe it may play a key role in proving once and for all that birds evolved from small meat-eating dinosaurs.

"(Microraptor) shows a number of modifications to the hips, tail and teeth which are in some ways intermediate between those of advanced meat-eating dinosaurs and birds. There also appears to have been feathers, adding more evidence to the view that feathers and feather-like structures predated the origin of birds," Dr. Paul Barrett, a professor at Oxford University said.

"It might represent the most bird-like dinosaur, " Xu told reporters.In addition to simply being birdlike, Microraptor possessed adaptations to its feet, including an extended toe, that may have allowed it to grasp onto the branches of trees. If this interpretation is correct, that would make Microraptor the first known arboreal, or tree dwelling, dinosaur.This tree-dwelling feature also may help prove that flight evolved from trees, rather from the ground."

The consensus has it that birds evolved from the 'ground-up' from fast running animals that gradually took to the air through becoming more efficient leapers, Barrett said. "(But), this (discovery) suggests that there might be some currency in an older, less fashionable idea that birds are descended from tree dwellers that evolved flight though a number of intermediate gliding phases."

This idea of flight originating from the trees has been suggested before, most notably by Texas Tech University paleontologist Sankar Chatterjee, but until now, as Barrett pointed out, there has been no solid anatomical proof.But, in order for flight to originate, many scientists say, the animal that takes to the sky has to be small, and until now each feathered dinosaur discovered by paleontologists has simply been too large to fly.

Microraptor is closing this size gap, many paleontologists say.The find "further shortens the morphological gaps between dinosaurs and birds," Xu said.University of Kansas paleontologist David Burnham, who named Bambiraptor, another bird-like dinosaur earlier this year, agreed with Xu, saying Microraptor helps to make the dinosaurs-to-bird theory more plausible because "it (Microraptor) is getting closer in size and age to the (first birds)."

``It does make the connection more likely than ever before,'' added Robert Reisz, a University of Toronto paleontologist and expert on vertebrate fossils.However, some scientists do disagree with the Xu's interpretation of this specimen, including Larry Martin, a University of Kansas paleontologist who is known for his refuting of the dinosaur-bird evolution theory.

"It (Microraptor) may still be a bit too big for the origination of flight," he said. Martin also pointed out that the extended toe and other adaptations of the foot do not clearly show that Microraptor was suited for an arboreal life.Although she believes that Microraptor does hold a key in understanding the origin of flight in birds, State University of New York paleontologist Cathy Forster is skeptical about the idea of the tree-dwelling hypothesis."I think they're kind of going out on a limb on that one (tree-dwelling)," she told New Scientist Magazine.

However, despite this disagreement, Microraptor is still considered a vital link in the evolution of avian flight. Surprising, to some, though, this small dinosaur was already a large part of the dinosaur-bird controversy before it was even named.In the autumn months of 1999, Canadian paleontologist Phil Currie and dinosaur sculptor Stephen Czerkas announced the discovery of an unbelievable new "missing link" between dinosaurs and birds in National Geographic magazine.

This specimen, which they named Archaeoraptor, was discovered to be a fake, composed of a long tail from one dinosaur and a body of another. Scientists pledged to name these two pieces individually, and now this is the case.

Microraptor was the tail of this specimen. Xu and his colleagues simply took the tail from this controversial chimera and matched it to the body of a different specimen. The result was Microraptor, which, unlike its earlier counterpart, is genuine and truly does hold importance in understanding the theory of dinosaur-bird evolution.