By JEFF DONN .c The Associated Press

(Dec. 7) - Researchers have unearthed what could be the smallest fossil
ever of an adult dinosaur: a crow-size creature that could help prove the
theory that birds evolved from little dinosaurs.

The 125 million-year-old dinosaur, called Microraptor zhaoianus, appeared
to have feathers and perch in trees, the researchers said. There is no
evidence that it flew, though.

It lived about 20 million years after the first known bird, the
Archaeopteryx. The Chinese researchers who made the latest discovery
believe the two creatures had a common ancestor.

Like the hulking Tyrannosaurus, little Microraptor belongs to a group of
dinosaurs known as theropods, meat eaters that walked on two legs. Many
paleontologists believe birds evolved from theropod dinosaurs. But
previous theropod fossils are bigger than typical birds, weakening the
theory.

Paleontologist Xing Xu, who led the research at the Chinese Academy of
Sciences in Beijing, said the newly discovered creature ''eliminates the
size disparity.'' Small size is viewed as necessary for flight in birds.

The researchers, who reported their discovery in Thursday's issue of the
journal Nature, said it came from a rich fossil field in the Liaoning
region of northeastern China.

The fossil stretches about 15 inches from head to tail. It shows some
birdlike characteristics in its teeth and bones, including an extended toe
that may have been used to grasp tree limbs, the researchers said.

They said its feet in some ways resemble those of Archaeopteryx and
Confuciusornis, another early bird. But some aspects of its skeleton, the
arrangement of its teeth and its long tail are clearly those of a
dinosaur, like the birdlike, 3-foot-long Bambiraptor reported earlier this
year, researchers said.

The researchers said the new fossil may ultimately help prove the theory
that flight evolved in tree dwellers, rather than in ground animals.

Paleontologist David Burnham at the University of Kansas said Microraptor
fleshes out the dinosaurs-to-birds theory because it is a birdlike
dinosaur that 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.

However, some researchers said it is hard to tell if the fossil really
represents a full-grown adult. Even if it does, ''it may still be a bit
too big for the origination of flight,'' said another University of Kansas
paleontologist, Larry Martin.

He also said Microraptor's feet do not clearly show a grasping, birdlike
toe.

Martin, a specialist in bird fossils, believes birds probably evolved from
archosaurs, ancient reptiles that he views as a parallel line of evolution
to the dinosaurs.

  AP-NY-12-06-00 1401EST

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