Soft-bodied fossils from a Silurian volcaniclastic deposit

Abstract

FOSSIL deposits that preserve lightly sclerotized and soft-bodied organisms are fundamentally important to our understanding of the history of life on Earth. They provide a much more complete record of ancient communities than does the normal shelly fossil record. Conditions during the Cambrian may have favoured the preservation of soft-bodied organisms1. Burgess Shale-type2–5 and Orsten-type6 faunas are becoming increasingly known from this roughly 40-million-year-long period for which we have a growing body of data on the metazoan radiation. Soft-bodied organisms are much less well represented in the subsequent 100 million years. The discovery of a new Silurian soft-bodied biota therefore has the potential to fill an important gap in our knowledge. The relatively deep-water marine environment represented is dominated by previously undiscovered arthropods and polychaetes. Here we describe a group of soft-bodied fossils from carbonate concretions within a volcanic ash, identifying an important new source of soft-bodied taxa.