TL;DR: In this article, the lower Cretaceous successions of the Risan Aneiza, El Tourkumanyia and Manzour areas (Northern Sinai, Egypt) were studied for biostratigraphic purposes.
TL;DR: Forty seven species (among them fourteen new that are listed below) of the following ammonite genera of the families Deshayesitidae Stoyanow, Oppeliidae Douville, Desmoceratidae Zittel, and Silesitidae Hyatt are described.
Abstract: Forty seven species (among them fourteen new that are listed below) of the following ammonite genera of the families Deshayesitidae Stoyanow, Oppeliidae Douville, Desmoceratidae Zittel, and Silesitidae Hyatt are described Neodeshayesites includes the new species N buergli, N striatus, N biplicatus, N longicostatus, N multicostatus, N euglyphoides and N tuberculatus Dufrenoyia includes the new species D renzi Pseudohaploceras includes the new species P gerhardti, P yucaense, P? yeseraense and P simile Melchiorites includes the new species M colombianus Zuercherella includes the new species Z etayosernai Other species belong to the genera Juandurhamiceras, Aconeceras, Pseudosaynella, Valdedorsella, Puzosia, Carloscaceresiceras, Kennicottia and Miyakoceras
TL;DR: The ammonite fauna of the Todai Formation can be divided into one horizon and two ammonite biostratigraphic zones (Aconeceras (A.) sp. Horizon, Epicheloniceras cf. claudii Zone and Diadochoceras nodosocostatiforme Zone, in ascending order), which are defined as discussed by the authors.