A NEW ORDOVICIAN EDRIOASTEROID FAUNA SHOWS STRONG CONNECTION BETWEEN MOROCCO AND NORTH AMERICA

Edrioasteroid echinoderms are poorly documented from Gondwana with the majority of their fossil record being recovered from North America and Europe. Although edrioasteroids were previously described from the Ordovician of Morocco by Chauvel (1971, 1978), these poorly preserved specimens are undiagnosable. New collections from the Arenig, Upper Fezouata Formation near Marrakech and another two localities from the El Caïd Rami area, 1. Caradoc, Izegguirene Formation near Zagora and 2. Asghill, Upper Tiouririne Formation in Tarhia, include six new edrioasteroid species placed into six genera, two of which are new. All specimens are preserved as molds in siliciclastic rocks that were studied from latex casts. The Arenig material includes two taxa. The first is a rather typical early pyrgocystid tentatively assigned to Pyrgocystis. Casts of the thecal interiors document hood plates as suggested by Guensburg and Sprinkle (1994). The other taxon is an unusual form that appears to be an edrioasterid, but has ambulacra and a peristome similar to isorophinids. The Caradoc-Asghill material from El Caïd Rami area includes four genera and species, three of which (Isorophus, Streptaster, and Belochthus) have North American counterparts. The other species is a new genus that has strong affinities to “Hemicystites” bohemicus and related taxa from Perigondwanan basins in Europe. This group of taxa is unrelated to North American Hemicystites and is characterized by extremely high cover plates born on narrow ambulacra and very wide peripheral rims. The presence of this species is not surprising given the close proximity of Perigondwanan Europe and North Africa during the Ordovician. However, the presence of Four North American taxa in North Africa (one Arenig, two Caradoc, and one Asghill) suggests close affinities of these faunas despite their wide geographic separation. It is predicted that with greater sampling from Gondwanan continents, edrioasteroids will be shown to be more common globally.