The shape of penguins in four dimensions : assessing macroevolutionary shifts in a constructional morphology framework : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Zoology at Massey University, Albany Campus, New Zealand

Describing the morphology of a clade through deep time provides rich insight into the drivers that shaped modern diversity. It is in this context that Adolph Seilacher developed the constructional morphology concept, in order to describe which are the major pressures acting on an organism's morphological appearance. The three components or apices of constructional morphology are the evolutionary history of the organism, the constraints placed on the structure, and the opportunity provided by adaptation. The structure of this thesis is based on the constructional morphology concept with each chapter focusing on the impact of each of the three components of constructional morphology with the scope to provide a novel approach to quantify morphological macroevolution. After introducing concepts of constructional morphology, geometric morphometrics and Bayesian statistics in Chapter 1, Chapter 2 presents an analysis to estimate the historical apex: a phylogenetic analysis based on the synthesis of previous published matrices, as well as a description of the giant fossil penguin Kairuku waewaeroa. The resulting phylogenetic tree indicates that the penguin evolutionary history was characterised by many monophyletic large groups that challenges previous results and indicate that the body plan of extinct penguins could be more diverse than previously thought. Chapter 3 focused on the structural apex, aiming to provide a generalisable Bayesian approach to estimate the size of extinct giant penguins in the context. By measuring the total volume of the femur and the humeral articular facet of the coracoid it was possible to generate two sets of models that together provided novel evidence in favour of reduced body mass estimates for giant penguins when compared with prior published estimates. Moreover, although the two sets of estimates are derived from two distinct features, the body mass estimates from the two models tend to converge, providing confidence in the accuracy of t