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Archaeopteryx leg feathers in new Paleobiology

From: Ben Creisler bh480@scn.org

In case this paper has not been mentioned yet:

Longrich, Nick, 2006. Structure and function of hindlimb 
feathers in Archaeopteryx lithographica
Paleobiology 32(3):. 417?431
This study examines the morphology and function of 
hindlimb plumage in Archaeopteryx lithographica. Feathers 
cover the legs of the Berlin specimen, extending from the 
cranial surface of the tibia and the caudal margins of 
both tibia and femur. These feathers exhibit features of 
flight feathers rather than contour feathers, including 
vane asymmetry, curved shafts, and a self-stabilizing 
overlap pattern. Many of these features facilitate lift 
generation in the wings and tail of birds, suggesting that 
the hindlimbs acted as airfoils. A new reconstruction of 
Archaeopteryx is presented, in which the hindlimbs form 
approximately 12% of total airfoil area. Depending upon 
their orientation, the hindlimbs could have reduced stall 
speed by up to 6% and turning radius by up to 12%. 
Presence of the ?four-winged? planform in both 
Archaeopteryx and basal Dromaeosauridae indicates that 
their common ancestor used fore- and hindlimbs to generate 
lift. This finding suggests that arboreal parachuting and 
gliding preceded the evolution of avian flight.