Abundant and diverse early Paleozoic infauna indicated by the stratigraphic record

Marine benthic animals have lived within the sediment since the late Precambrian. An abundant early Paleozoic infauna is indicated by bioturbated zones and diversity of deposit-feeder and suspension-feeder trace-fossil genera. Burrow depths extended tens of centimetres below the sediment-water interface. Trace-fossil evidence of an abundant early Paleozoic infauna conflicts with evidence from the shelled fauna, which lacks infauna. This requires reinterpretation of early Paleozoic community structure and raises new questions about interactions between early Paleozoic soft-bodied and skeletonized animals.