Comment on "Narrow primary feather rachises in Confuciusornis and Archaeopteryx suggest poor flight ability".

Nudds and Dyke (Reports, 14 May 2010, p. 887) compared the rachis diameters of the primary feathers of Archaeopteryx and Confuciusornis to those of modern birds and found that the primary feathers of these two basal birds were too weak to support sustained flight. Our measurements of Confuciusornis specimens suggest that their conclusions need to be further evaluated.