Trace fossils from the Lower Cambrian Mickwitzia sandstone, south-central Sweden

The Mickwitzia sandstone, south-central Sweden, consists of about 10 m of Lower Cambrian clastic sediments deposited in an epicontinental setting. An in formal, Iithologically based subdivision, A-E, is introduced. A thin basal conglomerate (interval A) is followed by thin-bedded sand and siltstone with clayey partings ( interval B and D ) and medium -grained sandstone (interval C), largely representing subtidal storm deposits. Interval E consists of thick-bedded shoreface deposits. Heterolithic intervals have well-preserved trace fossils, including Cruziana, Rusophycus, Gyrolithes, Treptichnus and Teichichnus. Beds with impure, often weakly cemented sandstone (interval C) have Rhizocorallium, Monocraterion and Skolithos. Trace fossils are dominated by infaunal feeding and feeding?-dwelling burrows; 40 ichnotaxa are recognized, representing the activity of but a few types of animals. The type material of Monocraterion tentaculatum ToreIl, 1870, is illustrated for the first time, and the relationship of Monocraterion to Skolithos and Rosselia is discussed. Previously poorly known taxa are described. Scotolithus mirabilis Linnarsson, 1871 , consists of a vertical shaft which in its lower part di verges into a wide broom-shaped arrangement. Spiroscolex spiralis (ToreIl, 1870) is a little-used name for burrows identical to Gyrolithes polonicus. Halopoa imbricata ToreIl, 1870, is a burrow related to Palaeophycus sulcatus, with a morphology dependant on sediment consistency: it is here assigned to Palaeophycus imbricatus. Fraena tenella Linnarsson, 1871, is assigned to Cruziana and considered a subjective senior synonym of Cruziana problematica. Phycodes pedum Seilaeher, 1955, should be assigned to Treptichnus.