Late Ordovician solutan echinoderms from the Western Tafilalt, Morocco

In the western Tafilalt area, eastern Anti-Atlas (Morocco), solutan echinoderms are a major faunal element of most echinoderm Lagerstätten occurring within the Lower Ktaoua Formation (late Sandbian–early Katian). For the first time, members of the class Soluta are formally described from Morocco and Africa. All solutans from the Lower Ktaoua Formation are identified as Dendrocystites aff. sedgwicki. Three size-related morphotypes, probably corresponding to successive growth stages (‘juvenile’, ‘adult’ and ‘gerontic’), could be distinguished within the abundant and well-preserved material from Morocco. The occurrence of the genus Dendrocystites in the western Tafilalt confirms the strong faunal affinities between Morocco and other regions of the Mediterranean Province (Czech Republic and Spain) in Late Ordovician times. In high palaeolatitude (peri-)Gondwanan areas, Dendrocystites was a gregarious solutan living in shallow, siliciclastic settings at or above the storm-wave base.