The Giganteuston Member of Öschingen (Humphriesianum Zone, Lower Bajocian, Swabian Alb), with comments on the genera Dorsetensia Buckman, 1892 and Nannina Buckman, 1927

Abstract

A section in the Lower Bajocian Giganteuston Member is described from Oschingen (Middle Swabian Alb). The examined part of this member yielded a sonniniid fauna of the romani horizon (Humphriesianum Zone, Romani Subzone), followed by a stephanoceratid fauna in the mutabile horizon (Humphriesianum Subzone). Oschingen is the type locality of Dorsetensia romani (Oppel) and Nannina deltafalcata (Quenstedt); in addition D. complanata Buckman and D. liostraca Buckman are reported from there. To clarify the taxonomic affiliation of these sonniniids, chorotypes of D. edouardiana (d’Orbigny) (= type species of Dorsetensia Buckman, 1892), D. lennieri Brasil and D. tessoniana (d’Orbigny) were studied; as well as topotypes of D. pulchra Buckman, D. liostraca Buckman, D. complanata Buckman, and D. regrediens (Haug).