Body size correlates with discrete character morphological proxies

Principal coordinates analysis (PCoA) is a statistical ordination technique commonly applied to morphology-based cladistic matrices to study macroevolutionary patterns, morphospace occupation and disparity. However, PCoA-based morphospaces are dissociated from the original data; therefore, whether such morphospaces accurately reflect body plan disparity or extrinsic factors, such as body size, remains uncertain. We collated nine character-taxon matrices of dinosaurs together with body mass estimates for all taxa and tested for relationships between body size and both the principal ordinated axis of variation (PCo1) and the entire set of PCo scores. The possible effects of body size on macroevolutionary hypotheses derived from ordinated matrices were tested by re-evaluating evidence for the accelerated accumulation of avian-type traits indicated by a strong directional shift in PCo1 scores in hypothetical ancestors of modern birds. Body mass significantly accounted for, on average, appro...