Meeting Abstract

36.3  Jan. 5  Structure and function of hind limb feathers in Archaeopteryx lithographica LONGRICH, Nicholas; University of Calgary longrich@ucalgary.ca

A restudy of the Berlin Archaeopteryx was undertaken to understand the morphology and function of the hind limb feathers. Feathers cover the legs of the Berlin specimen, extending from the cranial margin of the tibia and the caudal margins of the tibia and femur. These feathers exhibit features of flight feathers rather than contour feathers, including asymmetrical vanes, curved shafts, and a self-stabilizing overlap pattern. These features are thought to facilitate lift generation in the wings and tails of extant birds, suggesting that the hindlimbs acted as airfoils. A new reconstruction of Archaeopteryx is presented, in which the hindlimbs form approximately 12% of the total airfoil area. Depending upon their orientation, the hindlimbs could have reduced stall speed by up to 6% and turning radius by 12%. Presence of a “four-winged” planform in both Archaeopteryx and Dromaeosauridae suggests that their common ancestor used both the fore- and hindlimbs to generate lift. This finding in turn suggests that arboreal parachuting and gliding may have preceded the evolution of avian flight.