A unique pericyclid from the Viséan of the eastern Anti-Atlas (Morocco) and other Helicocyclinae n. subfam. (Goniatitida)

Abstract

The Jebel Begaa region of the eastern Anti-Atlas in SE Morocco yielded a single, very well-preserved goniatite that is closely related to Helicocyclus divergens Riley, 1996 from the lower Viséan (Chadian) of northern England. Both are placed in a new genus, Tectocyclus n. gen., with the Moroccan T. herbigi n. sp. as the type species. Characteristic are its subtriangular suture elements, which distinguish it strongly from Helicocyclus gracillimus Schindewolf, 1951, which is revised based on the re-examination of its types. The type-species of Helicocyclus is characterized by wide, bell-shaped lateral lobes, unlike as in described helicocyclids from the upper Tournaisian and Viséan of North Africa, Russia, and Central Asia. These are assigned, partly with reservation, to Serpenticyclus n. gen., with the oldest species, Helicocyclus fuscus Korn, Bockwinkel, Ebbighausen, and Klug, 2003, as the type-species. All three genera form the Helicocyclinae n. subfam., which first appeared in North Africa, migrated at the end of the Tournaisian across the Variscan Sea to the southern shelf of Laurussia, to Central Asia, and to the Urals seaway, where it survived into Arundian levels of the Viséan.