Washington: In what could alter the textbooks, researchers have declassified dinosaurs as being the great-great-grandparents of birds.
After re-examining a sparrow-sized fossil from China, they discovered that birds did not evolve from ground-dwelling dinosaurs.
"The birdlike fossil is actually not a dinosaur, as previously thought, but much rather the remains of a tiny tree-climbing animal that could glide," explained researchers Stephen Czerkas from Dinosaur Museum in Blanding, Utah, and Alan Feduccia from University of North Carolina.
The fossil of the scansoriopteryx (`climbing wing`) was found in Inner Mongolia, China.
It was previously classified as a theropod dinosaur from which many experts believe flying dinosaurs and later birds evolved.
In the study, researchers used advanced methods to reveal structures not clearly visible before.
These techniques made it possible to interpret the natural contours of the bones.
"Scansoriopteryx unequivocally lacks the fundamental structural skeletal features to classify it as a dinosaur," Czerkas added.
They also believe that dinosaurs are not the primitive ancestors of birds.
The Scansoriopteryx should rather be seen as an early bird whose ancestors are to be found among tree-climbing archosaurs that lived in a time well before dinosaurs.
"Scansoriopteryx is a basal or ancestral form of early birds that had mastered the basic aerodynamic maneuvers of parachuting or gliding from trees," the duo maintained.
"Instead of regarding birds as deriving from dinosaurs, scansoriopteryx reinstates the validity of regarding them as a separate class uniquely avian and non-dinosaurian," Feduccia contended in the study appeared in Springer`s Journal of Ornithology.