Narrow Primary Feather Rachises in Confuciusornis and Archaeopteryx Suggest Poor Flight Ability

Abstract

Poor Flight of the Ancients In order to fly, the feathers of birds must be strong enough to support the bird's weight without breaking or bending. The main part of a feather providing structural support is its central shaft, which stiffens the feather along its length. In modern birds, this is hollow to reduce weight. Nudds and Dyke (p. 887 ) show that the cross-section of the shaft of the Mesozoic birds Archaeopteryx and Confuciusornis was much smaller than that of modern birds. Calculations imply that even if it was solid, it would have been too weak to support powered flight and barely strong enough to allow gliding. Thus, powered flight probably arose later in the evolution of birds and these early birds were poor fliers.