Quantifying navigational capacity in trace fossils using spectral bandwidths: Applications for animal movement ecology through the Ediacaran–Cambrian transition

Small- to meso-scale movement patterns in invertebrate animals reflect anatomy, ethology, sensation, perception, and interactions with immediate environments. Trace fossils provide exceptional windows into these movements in deep time, yet quantitative metrics for assessing organismal navigational capacity at such scales remain limited. Here, we advance methodological approaches in ichnology by integrating modern and fossil datasets and, for the first time, introducing the concepts of bandwidths and sum of bandpasses to quantify the range of spatial frequencies expressed in locomotory trajectories. We demonstrate that locomotory modes including creeping, appendicular motion, and muscular waves exert strong control on bandwidths and bandpasses, with appendicular locomotion achieving the highest navigational performance. Mechanical resistance (e.g., drag force), reduced sensory range associated with deeper burrowing, and mismatches between the characteristic scales of the trace-maker perception and environmental information landscapes may reduce bandwidths; however, the resulting values remain constrained within the upper bounds imposed by locomotory modes. When the organismal sensory range matches the characteristic scale of landscape heterogeneity, the navigational capacity expressed by these two metrics peaks. Fossil evidence indicates that creeping emerged first, followed closely by coordinated muscular modes during the Ediacaran–Cambrian transition. These early muscular animals acted as pioneering ecosystem engineers, whose burrowing reshaped benthic community by altering microbial mats and ecological dynamics. The bandwidth framework exemplifies the growing trend in quantitative ichnology, offering robust tools to assess movement ecology and trace fossil behaviour, and providing new insights into the coevolution of animals and their environments.

Type

Journal Article

Item Description

NHM Repository

ISSN

0031-0182