Archaeoptryx

SCIENTIFIC CLASSIFICATION: Aves

TIME PERIOD: Jurrasic

HABITAT: Coastal regions

DESCRIPTION:

Flight:

Two models of the evolution of flight have been proposed: The 'tree's down' model and the 'ground up'. In the former, birds evolved from ancestors that lived in trees and could glide down much like today's flying squirrel. In the "ground-up" model, the primitive birds might have lived on the ground and made long leaps. The flight stroke may have developed as an extension of the grabbing forearm motion that smaller, agile theropods such as Deinonychus might have used to grab and hang on to prey or trees for support.Till recently, it was believed that the ground up model would'nt have worked due to the large amount of thrust needed to get it air-borne. But now, scientists believe that the ground-upmodel might work. They say that the Archaeopteryx could run with it's legs, while flapping with the hands. Thus the wing shape, along with it's flapping, gave enough thrust to the bird. All living birds that are not flightless have a keeled sternum to which the large, powerful flightmuscles attach. Archaeopteryx, on the other hand, had a comparatively flat sternum. Although it is currently believed that Archaeopteryx could sustain powered flight, it was mostly not a strong flier.

ITS PART IN EVOLUTION TABLE: The Archaeopteryx was the intermediate step between reptiles and birds.