Development, Diversity And Evolution Of Reptilian Skull Shape

What factors determine animal shape, both during the life of an individual and during evolution? Identifying the forces shaping organismal form and biodiversity is recognised as one of the great scientific challenges of the 21st century. Addressing this challenge demands a large-scale, interdisciplinary approach capable of disentangling the numerous and complex factors known to influence animal form.

Vertebrate skulls are enormously diverse, and are shaped by predetermined developmental programmes and evolutionary history, as well as by various functional demands - housing and protecting the brain and sense organs, feeding, interactions with other organisms (communication, combat), and even the external environment. All of these factors work together to control shape; however, it is unclear to what extent each contributes to final adult form or how they act during the evolution of a lineage. My ambitious proposal will bring together large datasets, cutting-edge methods, and world-class expertise to precisely identify the determinants of skull shape at two very different timescales: during the development and growth of an individual, and through evolutionary time.

Reptiles (both living and fossil forms) are an ideal model system for investigating the impact of multiple factors on skull shape: they occupy diverse terrestrial, aquatic, marine and aerial habitats; consume a wide range of foods; exhibit enormous differences in body size; and feature an excellent fossil record stretching back over 300 million years. In order to document changes in reptilian skull shape and pinpoint the forces driving these changes, I will apply a holistic approach involving: advanced 3D imaging and visualization of the skull and (for living reptiles) soft tissues of the head; contemporary morphometrics analyses to quantify form; and state-of-the-art biomechanical modelling techniques - including musculoskeletal modelling and finite element analysis - to rigorously determine skull performance, such as bite forces, jaw closing speed, and skull strength. These models will be refined and validated using new information on muscle architecture and biological material properties collected during the project. The proposed research is particularly timely as it will draw on a wealth of data - anatomical, experimental, phylogenetic and developmental - from my own previous work and from ongoing collaborations. Integrating these disparate strands of information will allow me to determine how different factors interact to shape reptilian skulls.

This work will bring us closer than ever to understanding one of the most important and fundamental questions in evolutionary biology: precisely how do complex forces interact with each other to drive organismal change and biodiversity? I will set new standards for performing truly multidisciplinary, comprehensive studies in functional morphology that can be applied to other organismal groups and body systems. The project will establish new and solidify existing UK and overseas collaborations, and provide vital training for two early career scientists. Workers across diverse fields - evolutionary and developmental biologists, palaeontologists, engineers, and ecologists and conservation scientists - will benefit from vast new data sets, and new workflows and methodological advances, sparking many future studies. Finally, the visual and technological aspects of this work, as well as its focus on charismatic living and fossil animals, will appeal to the general public, generating engagement opportunities and media interest. Project results will be incorporated into teaching and a museum exhibit at UCL's Grant Museum, and 3D digital models will be made freely accessible, leading to greater appreciation of how organisms develop and evolve, and the importance of researchers across different fields working together to address big questions.