Vestigichnus annulus Radtke, Hook, Campbell et Golubic, 2024

Key feature (diagnosis): V. annulus or the ring-shaped morphs up to 150 mm diameter, are similar to V. discus plaque morphs and can be smaller or larger than the typical diskshaped etch-fields. They consist of a depressed ring with a central area that remains elevated (not shown), or which is occupied by a different structure, e.g. a sporangial neck or similar contact of traces to the substrate surface (Fig. 4b). Vestigichnustype etch fields have been observed associated with euendoliths contacting or exiting the substrate. The selected example shows a well-developed tubular euendolith Orthogonum tubulare RADTKE, 1991, that penetrated the substrate, parallel to its surface and generated two connections that exited the substrate, both surrounded by a halo of V. annularis etchings (Fig. 4b; 18f, arrows). The etching seems to have occurred over time.