Lethaia Review Names for trace fossils 2.0: theory and practice in ichnotaxonomy

A uniform approach to ichnotaxonomy has been for the most part positively received by the scientific community. We carry it further here, presenting a revised treatment of trace fossil groups. These should include cololites and regurgitalites as well as root traces. Signs of human technology may be seen as traces; however, they should not be named following the principles of zoological taxonomy and rules of zoological nomenclature. Microbially induced sedimentary structures are not considered as traces and neither are structures resulting from bioclaustration. The latter, also known as galls and embedment structures, may be named as cecidotaxa (cecidofamilies, -genera, -species; briefly cfam., cgen., csp.) and, as such, they are governed by the International Code of Zoological Nomenclature. Cecidotaxa do not compete for synonymy with ichnotaxa, other parataxa or biotaxa. A revised list of ichnotaxobases includes the arrangement of subunits as well as (in a restricted way) size and bioglyphs. The principal type of substrate may serve as an ichnotaxobase, especially in bioerosion traces, but its sole use should be avoided, unless informed by knowledge about the behaviour of specialist producers. For the purpose of the nomenclatural code, we further propose to define ‘fossil’ as ‘not demonstrably postdating the beginning of the Holocene’ and provide a revised definition of ‘ichnotaxon’.