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

Abstract

The capacity for aerial maneuvering shaped the evolution of flying animals. Here we evaluate consequences of aviaian morphology for aerial performance (1,2) by quantifying static stability and control effectiveness of physical models (3) for numerous taxa sampled from within the lineage leading to birds (Paraves, 4). Results of aerodynamic testing are mapped phylogenetically (5-9) to examine how maneuvering characteristics correlate with tail shortening, fore- and hindwing elaboration, and other morphological features (10). In the evolution of the Avialae 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 some features normally considered in light of development of a power stroke may play important roles in control.Comment: 12 pages, 6 figures, 1 supplemental figures and 5 supplemental table