Spiral trace fossils from the Permian Ecca Group of Zululand



The presence of spiral trace fossils is reported for the first time from six localities in strata of the Vryheid Formation of the Ecca Group (Lower Permian) in South Africa. These localities are all in the northeast part of the main Karoo basin of sedimentation. The fossils arc assigned to the ichnospecies Spirodesmos archimedeus, representing the spiral trail or burrow of a deposit-feeding organism. In contrast to other reports of spiral trace fossils, the Spirodesmos traces described here were formed in a shallow-water environment. This is established on both sedimentary and ichnofacies evidence. Associated trace fossils include Skolithos, Corophioides and Siphonichnus, all of which arc members of the Skolithos ichnofacies of Scilacher. The occurrence of Spirodesmos in this ichnofacies suggests that these strata were deposited in a marine basin.