Quantitative Tools to Decipher Changes in Behaviour and Bioturbation using Trace Fossils Spanning the Ediacaran-Cambrian Transition
Date
2025-01-27
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
ORCID
0000-0002-0874-8879
Type
Thesis
Degree Level
Doctoral
Abstract
Trace fossils, the fossil evidence of animal behaviour, offer a key historical perspective into both (1) behavioural and sensory system innovations and (2) the impact of bioturbation on the biosphere (i.e.,, ecosystem engineering). 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 (Chapter 2). 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 a case study, this method was applied to late Cambrian specimens of the trace fossil Cruziana semiplicata and successfully identified statistically distinct morphotypes which may represent distinct behaviours (Chapter 3). Further analysis of Ediacaran and Cambrian horizontal trails (e.g., Helminthoidichnites, Parapsammichnites and Psammichnites) revealed, among other features, the presence of temporal autocorrelation in the early Cambrian (Chapter 4) and spatially heterogeneous behaviours (Chapter 5). This research highlights the immense potential of quantitative methods in ichnology and provides a groundwork for future research.
Description
Keywords
Ichnology, Quantitative, Ediacaran, Cambrian
Citation
Degree
Doctor of Philosophy (Ph.D.)
Department
Geological Sciences
Program
Geology