COMPUTATIONAL FLUID DYNAMICS: A POWERFUL TOOL FOR ELUCIDATING FUNCTION IN FOSSIL TAXA

Deciphering the relationship between form and function in fossil organisms is key to reconstructing their mode of life and evolutionary history, but is problematic where there is no clear modern analogue – as is the case for many extinct Palaeozoic groups. Computer models offer a potential solution to this problem, however, as they can often be used to explore fossil functional morphology without specifying an extant interpretive analogue. Computational fluid dynamics (CFD) is one such modelling technique. It generates quantitative data based on numerical simulations of fluid flow, which can be used to test functional hypotheses in fossil taxa; however, to date CFD has been applied only very rarely in palaeontology.

Here, we present a case study of the use of CFD for investigating the functional morphology of cinctans, a problematic group of Cambrian echinoderms. For this, we employed a mesh-free method called smoothed particle hydrodynamics, which uses GPU acceleration to dramatically improve computational efficiency. Flow was simulated past digital reconstructions of the Spanish cinctan Protocinctus in a range of positions relative to the on-flowing current and the sediment–water interface. Simulation results show that the shape of Protocinctus influenced flow structure in significantly different ways depending on the position of the animal, suggesting that it faced away from the current with part of the lower surface resting on top of the sediment to maximize feeding efficiency and stability.

This work highlights the great potential of CFD for informing functional analyses of Cambrian echinoderms and, indeed, any fossil group where the three-dimensional form is known. The recent development of high-resolution imaging techniques (e.g. X-ray micro-tomography), increasingly powerful computer hardware and freely available visualization and simulation software means this approach is now feasible for research purposes, opening up an exciting new avenue in palaeontological studies of functional morphology.