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Arboreal Theory of Flight
Transcript of Arboreal Theory of Flight
Now extinct, this reptile had rudimentary wings to facilitate flight or gliding when descending from forest canopies. It is actually believed to be an intermediary between reptiles and birds, since it closely resembles domesticated fowl, such as the chicken (Red Junglefowl). Feathers cover the legs of the Archaeopteryx. These feathers exhibit features of flight feathers rather than contour feathers, including vane asymmetry, curved shafts, and self-stabilizing overlap pattern. These features facilitate lift generation in the wings and tails of birds, which means the hindlimbs acted as airfoils. The presence of the four winged platform in both the Archaeopteryx and basal Dromaeosauridae indicates that their common ancestor used both forelimbs and hindlimbs to generate lift. A four-winged dromaeosaur provides evidence for an arboreal-gliding origin. It has asymmetric flight feathers on the forelimb, AND on the hindlimb. Leg feathers are present in many fossil dromaeosaurs, early birds, and living raptors. A computer simulation of the flight performance of Microraptor suggests that its biplane wings were adapted for gliding between trees Modern research suggests that the Archaeopteryx scaled large trees and then, if convenient, would leap away and glide down slowly to the ground floor. This method proved to be a more efficient means of transportation than the bipedal locomotion ubiquitous of related reptilian species. Uncannily, the Archaeopteryx is comparable to the modern Flying Squirrel, a mammal with similar avian features. Chicken Flying Squirrel The presence of flight feathers on the hindlimbs in inconsistent with the cursorial hypothesis and the wing-assisted incline running hypothesis, BECAUSE, in both of those scenarios, flight feathers would serve no purpose and would impede locomotion. The evidence, therefore, supports an arboreal origin of avian flight.