Response to Serrano and Chiappe

Abstract

In the recent study in Current Biology by Pei and colleagues1, we used two proxies — wing loading and specific lift — to reconstruct powered flight potential across the vaned feathered fossil pennaraptorans. The results recovered multiple origins of powered flight. We respectfully disagree with the criticism raised by Serrano and Chiappe2 that wing loading and specific lift, used in sequence, fail to discriminate between powered flight and gliding. We will explain this in reference to our original conservative approach.