Shifts in stability and control effectiveness during evolution of Paraves support aerial maneuvering hypotheses for flight origin

Abstract

ABSTRACTThe capacity for aerial maneuvering was likely a major influence on the evolution of flying animals. Here we evaluate consequences of paravian morphology for aerial performance (Dudley and Yanoviak, 2011; Smith, 1952) by quantifying static stability and control effectiveness of physical models (Evangelista et al., 2014) for numerous taxa sampled from within the lineage leading to birds (Paraves, Xu et al., 2011; Gauthier and Padian, 1985). Results of aerodynamic testing are mapped phylogenetically (Maddison and Maddison, 2010; Zhou and Li, 2010; Li et al., 2010; O’Connor et al., 2011; Cracraft et al., 2004) to examine how maneuvering characteristics correlate with tail shortening, fore-and hindwing elaboration, and other morphological features. In the evolution of Paraves we observe shifts from static stability to inherently unstable aerial planforms; control effectiveness also migrated from tails to the forewings. These shifts suggest that some degree of aerodynamic control and and capacity for maneuvering preceded the evolution of strong power stroke. The timing of shifts also suggests features normally considered in light of development of a power stroke may play important roles in control.