Biostratigraphy of the Unteres Flöz (Upper Aalenian, Murchisonae Zone, Haugi Subzone, sinon biohorizon) at the type locality of the Eisensandstein Formation (Braunjura Group) at Aalen (E Swabian Alb, SW Germany)

Abstract

The ammonite assemblage of the Unteres Flöz (= “lower seam”) at Aalen (SW Germany) represents the herein newly introduced sinon biohorizon of the uppermost Haugi Subzone (Murchisonae Zone, Upper Aalenian). The biohorizon is the type horizon of the ammonite taxa Ludwigia obtusa (Quenstedt) [= L. haugi (Douvillé) auct.], L. crassa Horn and Staufenia sinon (Bayle). Despite an enormous morphological variation within the representatives of these genera Ludwigia Bayle, 1878 and Staufenia Pompeckj, 1906 in the sinon biohorizon, we consider that they belong to a single chronospecies.