Response to comments on "Narrow primary feather rachises in Confuciusornis and archaeopteryx suggest poor flight ability"

Paul and Zheng et al. challenge our conclusions regarding the flight of Confuciusornis and Archaeopteryx, which derive from our method of assessing flight ability from estimated feather strength. They suggest that our mass and rachis data for these fossil birds are incorrect. Neither comment, however, invalidates our method nor alters conclusions of poor flight ability based upon our original data. We encourage researchers to use our method before critiquing our conclusions regarding early bird flight.