Discophyllum, a common large eldonioid (problematic discoidal fossil) from sandstone strata bearing the Tafilalt Biota (Late Ordovician) of Morocco

Abstract The Tafilalt Biota of southern Morocco has been shedding valuable light into the biodiversity and palaeoecology of the Upper Ordovician. The fossil remains of lightly-sclerotised discoidal organisms (eldonioids) are a common component among the Tafilalt assemblages preserved in sandstone. In this region, these non-biomineralised stem-group deuterostomes are widely distributed in the Upper Tiouririne Formation of eastern Tafilalt and in a relatively small area of northwestern Maïder, at the top of the First Bani Group. Within this stratigraphic range (Sa1–Ka3), the record is virtually restricted to a single species, Discophyllum peltatum Hall, which was locally described as ‘ Eldonia berbera ’ Alessandrello & Bracchi, a junior synonym. Although D. peltatum is the most abundant “soft-bodied” organism of the Tafilalt Biota, the Moroccan material has not yet been the subject of a modern taxonomic revision. An important study on the African fossils, which formed part of a PhD Thesis submitted in 2012 at the University of Galway (Ireland), remains unpublished. Therefore, we deemed it necessary to revisit this topic and consolidate the knowledge of the Tafilalt Biota in the present study, while formalising the proposal of certain suprageneric taxa (Order Eldonida, nov., and Family Paropsonemidae, nov.) underpinning the classification of eldonioids.