Research Article| December 29, 2022 DEEP TIME BIOGEOMORPHOLOGY 2: ANIMALS AS ANCIENT ECOSYSTEM ENGINEERS ANTHONY P. SHILLITO; SHILLITO 1Department of Geological Sciences, University Saskatchewan, 114 Science Place, Campus Drive, Saskatoon SK S7N 5E2, Canada Search for other works by this author on: GSW Google Scholar NEIL S. DAVIES; DAVIES 2Department Earth Cambridge, Downing Street, Cambridge ...

1. Introduction. In their interesting paper Davies and Gather draw our attention to what they call the " small print " in definitions of breakdown. Working from a formal group structure and a notion of equivariance, they show by a number of examples that a definition of breakdown may be void if not accompanied by a reasonable and precise group structure. This leads them to what we would label t...