FLUID DYNAMICS OF THE ENIGMATIC EDIACARAN ORGANISM PTERIDINIUM

The Ediacara biota represent the first major radiation of macroscopic eukaryotes, and so are key to understanding the origins of the modern, animal-dominated biosphere. However, many Ediacaran organisms possessed highly unusual morphologies, that have no parallels among extant animal groups. Although paleontologists have struggled to understand the biology and ecology of these organisms, 3D modeling and fluid physics analyses offer a powerful way to test different hypotheses surrounding movement, feeding, and reproduction.

Here, we used the 3D Computer Aided Design (CAD) software Rhinoceros 3D to construct the Ediacaran taxon Pteridinium. We scaled our models to a range of sizes based off field measurements and published specimens. There is some debate surrounding the morphology of the taxon, thus we varied the overall body shape and number of veins to test different morphological reconstructions that have previously been proposed. We then placed the 3D models in simulated flow to gain an initial sense for how their unusual morphologies interact with moving fluids. We combine these fluid dynamics simulations with physical experiments performed in a flume tank, both for ground-truthing and to look for small-scale flow features not captured in virtual experiments.

These experiments provide a basis for formulating hypotheses, which we will test between competing feeding modes of these organisms, as well as their effect on current flow through entire Ediacaran benthic communities.