Abstract We examined the palaeogeographical distribution of selected Cambrian trace fossils. Astropolichnus hispanicus , Climactichnites , Syringomorpha nilssoni and early examples of Paleodictyon all have a restricted palaeogeographical distribution, probably representing that of their producers. A cosmopolitan distribution is seen in Didymaulichnus miettensis and in early examples of Rusophycus and Dactyloidites . Oldhamia shows a wide distribution in Lower Cambrian deep-sea sediments although that of Oldhamia geniculata is restricted.

Abstract Earliest Cambrian fine-grained sediments appear to have been firm close to the sediment-water interface. As a result there was a high preservational potential of shallow tiers. There is limited evidence for a mixed layer at this time; rather, most of the preserved trace fossils were open burrows. Later in the Cambrian, depth of sediment mixing increased but firmground conditions are still found relatively close to the sediment-water interface. The development of the mixed layer and properties of Cambrian muddy sediments have numerous stratigraphic and ichnological consequences. These include secular trends in the preservation of event beds and shallow-tier trace fossils including Rusophycus and Cruziana .