The tornoceratid ammonoids from the Roteisenstein Formation of Dillenburg (Cephalopoda, Ammonoidea) Author Korn, Dieter 304FF76E-83FB-478C-AAA9-BD5769C80918 Museum für Naturkunde, Leibniz-Institut für Evolutions- und Biodiversitätsforschung, Invalidenstrasse 43, D- 10115 Berlin, Germany. dieter.korn@mfn.berlin Author Bockwinkel, Jürgen 1F1EDD42-B1CE-425C-9CBD-D19658A6C453 Dechant-Fein-Strasse 22, D- 51375 Leverkusen, Germany. jbockwinkel@t-online.de text European Journal of Taxonomy 2022 2022-03-21 806 32 51 http://zoobank.org/a2b2a310-8c8c-41b0-b934-1666129b7d90 journal article 20137 10.5852/ejt.2022.806.1699 ee706a5b-3456-4097-b44d-2ebfd40a0824 2118-9773 6373961 A2B2A310-8C8C-41B0-B934-1666129B7D90 Genus Lentitornoceras gen. nov. urn:lsid:zoobank.org:act: 99D306D3-03BA-4D2A-BBF6-9F47653F5907 Type species Lentitornoceras materni gen. et sp. nov. Diagnosis Genus of the subfamily Tornoceratinae with strongly compressed conch, umbilicus closed in the adult stage. Without ventrolateral grooves. Ornament with biconvex growth lines, without ribs. Sutural formula E A L I; adventive lobe broadly rounded, asymmetric with steep dorsal flank; ventrolateral saddle narrow. Etymology After the Latin nomen ‘ lens ’ = ‘lentil’, because of the conch shape, and the reference to the genus Tornoceras . Included species Only the type species. Remarks Lentitornoceras gen. nov. is easily distinguished from all other tornoceratids by its extremely discoidal conch shape. Furthermore, the course of the growth lines shows differences to other genera; in Lentitornoceras a clear dorsolateral projection is developed, which is only very indistinct in the other genera.