Arboreal Theory: The Origin Of Avian Flight

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ORIGIN OF FLIGHT *The origin of avian flight is a classic macroevolutionary transition with research spanning over a century( Simpson, 1944). *Traditionally, scholars have advanced two theories for how bird flight evolved. Arboreal theory – *The arboreal model hypothesizes that the proavis was a small early archosaur that leaped from branch to branch, or from a branch to a tree trunk, and that this behavior was key in the origin of the first flying archosaur (Heilmann, 1927). *According to this theory flight evolving from an arboreal gliding stage would seem to be relatively easy. *But this theory has little support from comparative biology as it requires the ability to climb trees and to glide.…show more content…
*Both the arboreal and the cursorial scenarios have explanatory gaps. *As far as tree dwellers go, of the hundreds of nonavian gliding vertebrates around today, not one flaps its appendages. *Why would natural selection have favored the development of little protowings in a theropod equipped with heavily muscled legs for running across the ground? Kenneth Dial (2003) explained origin of flight in birds. *He pointed out that the step-by-step adaptations that led to fully developed flight

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