Ichnofacies: a mixture of taphofacies and biofacies

The environmental significance of individual ichnofacies has become a point of debate, and the Scoyenia ichnofacies is not clearly defined. Removal of the marine/non-marine boundary from ichnofacies definitions, as well as the bathymetry control, would render the Scoyenia ichnofacies unnecessary and would consolidate the definitions of the remaining ichnofacies. The constitution of the remainder is far from uniform. In some, the characteristic features are influenced by taphonomic bias more than by ecological factors, and thus these ichnofacies are in effect taphofacies (Skolithos, Cruziana and, especially, Zoophycos and Nereites). Others, on the other hand, have a primarily ecological definition and function as biofacies (Glossifungites, Trypanites, Teredolites and Psilonichnus), taphonomic bias playing a relatively minor role. Opportunistic occurrences of Skolithos in storm deposits do not fall within the Skolithos ichnofacies sensu stricto, and may be regarded as a separate Arenicolites ichnofacies, having an ecological character. □Trace fossils, ichnofacies, salinity.