THE DEVELOPMENT OF FLIGHT
The first birds that developed came in an immense variety of shapes and sizes. The unique designs of their skulls, wings, feet, and teeth are all indicative that even at this early stage of evolutionary history, birds were specializing. They were settling in to very specific ecological niches like sap-eaters, seed-feeders, insectivores, fish-eaters, and carnivores. Competition for dinosaurs at this time was fierce and when the battle for resources on the ground became too much, the dinosaurs (early birds) took to the trees and developed an arboreal lifestyle. This coincided with the use of their wings and feathers for gliding and eventually flight. Soon after Archaeopteryx, the features of the bones and muscles of the wings and rib-cages of these bird-like dinosaurs began to give rise to the powered flight of birds that we have come to know today.