Research Themes

I use biomechanical techniques to deduce function. Although fossils are long dead and their body parts either mineralised or degraded, ancient skeletons were still subject to the same physical rules that govern our own skeleton. Hence we can apply these principles to fossil organisms. My group and I employ a range of computational approaches such as computed tomography (CT) scanning, coupled with engineering analysis such as finite element analysis (FEA) to reconstruct stress and strain in the skeleton during function. More recently we have been employing empirical approaches such as strain gauge analysis, work-to-fracture material studies and quantitative microwear to substantiate and validate our computational approaches. We are also now working increasingly with morphospaces, firstly to quantify shape variation (disparity) and identify possible constraints (functional, historical) on form, but also to quantify functional diversity across taxa and through time.

Currently, most of the research that I and members of my group performs fits under the following broad themes:-

1. Form and function
Underpinning all the research we perform is the relationship between form and function. An age old question, the answer is not always straightforward. Some of the research we perform tackles this question in a hypothesis driven manner, asking why is the skeleton built in a particular way and how does a skeleton or a certain shape (form) then function (e.g. Rayfield et al. 2001; Rayfield 2004; Rayfield 2005a). We are also interested in whether organisms are optimal (probably not) and do they follow biomechanical predictions (e.g. Rayfield & Milner 2008). If they are not optimal, then why not? How do constraints influence the relationship between form and function? We ask if organisms with similar ecologies show morphological and functional convergence (e.g. Rayfield 2005b; Rayfield et al. 2007; Pierce et al. 2008, 2009). To date this work has focused on dinosaurs, crocodilians, dicynodont synapids and early mammals.

2. Functional and ecological diversity through time
A recent area that we are interested in is codifying functional diversity through time. What this means is using metrics of biomechanical performance, such as mechanical advantage of the jaws, second moments of area, stress/strain plots, tooth characters, etc., and tracking how these features change in different organisms and through time. Interesting questions to ask is whether functional diversity is linked to morphological and taxonomic diversity, and what possible impact extrinsic environmental factors impose on these patterns. If we track functional diversity through time, does this mirror morphological and taxonomic diversity? We can ask the same kind of questions as we would ask of morphological or taxonomic diversity, such as, is functional diversity affected my major environmental changes? Is diversity achieved rapidly after innovations or not? Do different organisms converge on similar functional solutions through time? If so, why so? See our papers on this topic in early jawed vertebrates (Anderson et al. 2011 Nature), early tetrapods (Neenan et al 2014 Proceedings B), archosaurs (Stubbs et al 2013 Proceedings B) and living and extinct crocodilians (Pierce et al. 2008; 2009).

3. Validation of computational methods
A substantial component of the research that I and my group perform involves computational analysis. One particular technique we are interested in is finite element analysis (FEA), first used by engineers and orthopaedic scientists to design-test cars and bridges, and femurs and hip implants. We use FEA to determine stress, strain and deformation in the skeletons of living and extinct animals during function (see Publications tab for a full list of references). This gives us an insight into why the skeleton is constructed in a particular way, and how the animal functioned. One of the key questions when undertaking this kind of computational analysis is how well do our results reflect reality? This is a major research program for our group, and we are undertaking this kind of FEA validation in the skulls of ostriches (Rayfield 2011) and pigs (Bright & Rayfield 2011a,b). We also use quantitative microwear as an alternative line of evidence for FE functional predictions (Purnell et al. 2013; Gill et al. 2014) We have also had success in matching the deformation of photoelastic gelatine to precise FE-models (Anderson et al. 2012) and are working on validating computational fluid dynamic models of flow around foraminifera with flow-tank settling experiments (Caromel et al 2014).