Quantitative tools to decipher changes in behaviour and bioturbation using trace fossils spanning the Ediacaran-Cambrian transition

<p dir="ltr">Trace fossils, the fossil evidence of animal behaviour, offer a key historical perspective into both (1) behavioural innovations and (2) the impact of bioturbation on the biosphere. Here, quantitative methodologies to track these events via trace-fossil datasets are investigated. After a review of methods to evaluate bioturbation impact it was found that trace-fossil models are useful to characterize styles of bioturbation impact but do not reflect bioturbation intensity or how it may change across populations. A potential best-practice model is outlined that quantifies the intensity of historical bioturbation impact such that it can be compared through time (<b>Paper 1</b>). To examine behavioural innovation, modern movement ecology research was referenced and a method to discretize horizontal movement paths in the fossil record was developed. As proof of concept, this method was applied to the early Cambrian trace fossil <i>Cruziana semiplicata </i>and successfully identified statistically distinct morphotypes which may represent distinct behaviours (<b>Paper 2</b>). Further analysis of Ediacaran and Cambrian horizontal trails (e.g. <i>Helminthoidichnites, Parapsammichnites </i>and <i>Psammichnites</i>) revealed, among other features, the presence of temporal autocorrelation in the early Cambrian (<b>Paper 3</b>). This research highlights the immense potential of quantitative methods in ichnology and provides a freely available groundwork for future research.</p>