Ethology of the trace fossil Chondrites: form, function and environment

The behaviour of the iconic ichnogenus Chondrites is re-evaluated based on review of existing literature and analysis of novel data (macroscopic, thin section and ESEM-EDX observations; CT-scans and resin peels of modern analogues; computer-controlled serial grinding; morphometric analysis and theoretical morphology). The bedding plane expression of Chondrites is well-constrained by morphometry: (1) the angle of dichotomy formed by a pair of adjacent branches is typically between 30° and 56° (interquartile range; mean: 47°); (2) branching order is between 1 and 9; (3) branches are, on average, nine times longer than wide. In the third dimension, downward branching is dominant but bundled shafts and upward branching may be present.