The orbit is one of several skull openings in the archosauromorph skull. Intuitively, it could be assumed that orbit shape would closely approximate the shape and size of the eyeball resulting in a predominantly circular morphology. However, a quantification of orbit shape across Archosauromorpha using a geometric morphometric approach demonstrates a large morphological diversity despite the fact that the majority of species retained a circular orbit. This morphological diversity is nearly exclusively driven by large (skull length > 1000 mm) and carnivorous species in all studied archosauromorph groups, but particularly prominently in theropod dinosaurs. While circular orbit shapes are retained in most herbivores and smaller species, as well as in juveniles and early ontogenetic stages, large carnivores adopted elliptical and keyhole-shaped orbits. Biomechanical modelling using finite element analysis reveals that these morphologies are beneficial in mitigating and dissipating feeding-induced stresses without additional reinforcement of the bony structure of the skull.
Bibliographical noteFunding Information:
Donald Cerio (Johns Hopkins University School of Medicine) and Emma Dunne (University of Birmingham) are thanked for discussion and helpful suggestions which substantially improved this study. Jordi Marcé Nogué (Universitat Rovira i Virgili, Tarragona) and two anonymous reviewers are thanked for constructive feedback on earlier version of the manuscript.
© 2022, The Author(s).
- Body Size
- Dinosaurs/anatomy & histology
- Orbit/anatomy & histology
ASJC Scopus subject areas
- Agricultural and Biological Sciences(all)
- Biochemistry, Genetics and Molecular Biology(all)
- Medicine (miscellaneous)