2021 Progressive Palaeontology 2021 Abstract Booklet

We also find links between the high global temperatures of the early Eocene and increased evolutionary rates of wing morphological evolution and a reduction in flight ability with the cooling of the Earth through the Cenozoic. [...] These changes to the moment arms and overall lines of action of the pectoral musculature appear to result from disparate changes to the shape of the scapulocoracoid and humerus between the different quadrupedal ornithischian groups, each of which may have consequently developed distinct locomotor styles. [...] All the biramous trunk limbs have the same morphology, and the only evidence of differentiation consists of the presence of progressively smaller posterior appendage pairs and some variability in the proportions of the proximal region that affect food mastication. [...] The expansion of the coronoid process, reduction of the post dentary bones, and appearance of a dual jaw joint, in eucynodonts is associated with increasing functional optimisation of the mandible, suggesting that functional optimisation was an important driver of the evolution of the mammalian mandible. [...] The results indicate that the simplified cross-sections were incapable of accurately capturing the strength of the whole organisms, however, do demonstrate that the robustness of the organism varies between morphological groups.