Ordovician conulariids of the Iberian Peninsula

Trabajo presentado en el International Geoscience Programme Project 653 Opening Meeting (2016), celebrado en Durham (Reino Unido), del 25 de septiembre al 1 de octubre de 2016Conulariids (class Scyphozoa, phylum Cnidaria) are relatively rare fossils which are widely distributed in Ordovician marine strata of North Gondwana and adjacent peri-Gondwanan terranes. However, Ordovician conulariids of the Iberian Peninsula (Spain plus Portugal), then part of the Gondwanan margin, have not yet been formally described or tabulated. Our examination of samples collected throughout the Iberian Massif revealed the presence of Archaeoconularia and Pseudoconularia. Pale yellowish-brown shales of Floian age in the Barrancos Formation (Ossa-Morena Zone) of Spain yield extremely rare, small attened specimens of Archaeoconularia sp. Darriwilian dark grey shales in six formations in the Central Iberian and Cantabrian zones collectively host rare specimens of at least two species of Archaeoconularia, one with ne nodes and the other with nodes that are coarse, and at least one species of Pseudoconularia. A third species of Archaeoconularia, characterized by very high apical angles, may also be present. A distinctive bed in Katian dark gray shales within the Cantera Formation yields at least one species of Archaeoconularia. Many specimens of Archaeoconularia from Darriwilian strata are in ated (uncompacted) and preserve the apertural region, which exhibits partial plicated closure of the oral end of the periderm. Plicated closure may have occurred in response to catastrophic burial of live conulariids. While taxonomically similar to Ordovician conulariid assemblages of other high latitude, Gondwanan and peri-Gondwanan localities, the Ordovician conulariid assemblages of Iberia di er from many of them, for example the Ordovician assemblages of Morocco and the Upper Ordovician assemblages of Bohemia, France and Jordan, in that they apparently do not exhibit monospeci c mass occurrences. Additionally, gigantic Archaeoconularia such as those present in Morocco have not been found in Iberia. In these respects the Iberian conulariids are perhaps most similar to those of Wales (Avalonian terrane), which likewise are rare, relatively small and occur in dark gray shales. These results extend the paleogeographical extent of a low diversity, cold-water, South polar Gondwanan/peri-Gondwanan conulariid realm, generally dominated by Archaeoconularia, which di ers markedly from the low to mid latitude, mid-late Ordovician Baltic and Laurentian realms, which were characterized by substantially higher taxonomic diversity at both the genus and species levels. Additional e ort should be extended to regions such as southwestern Libya, where collecting by one of us (JCG-M) in upper Katian rocks has produced fragmentary specimens of Archaeoconularia, Conularia Miller in Sowerby, 1821 and, possibly, Conulariella Bouček, 1939, previously known from Bohemia and Armorica.This is a contribution to the projects CGL2012-39471 and IGCP 653Peer reviewe