New rhombiferan blastozoans (Echinodermata) from the Late Ordovician of Morocco
Résumé
New Upper Ordovician Echinoderm–Lagerstätten from the Anti-Atlas of Morocco have provided large collections of blastozoan echinoderms. The echinosphaeritid Echinosphaerites dianae n. sp. preserves the oral region, stem and brachioles, characteristics absent in many species of the same genus. Homocystites adidiensis n. sp. is represented by almost 50 specimens that provide details on the growth in this taxon. This is the only species of Homocystites with granules in the external ridge of the outer proximal stem columnals. The genus Rhombifera is recognized for the first time in Morocco based on one partially preserved thecal plate. Assemblages are characterized by low diversity of rhombiferan blastozoan echinoderms that provide further palaeogeographical links at genus level with Gondwana, Baltica and Avalonia.