Article: Two new Bajocian microconch otoitid ammonites and their significance

Two new Bajocian (Middle Jurassic), microconch species belonging to the ammonite family Otoitidae, Trilobiticeras (Trilobiticeras) cricki nov. and Emileia (Otoites) douviltei nov., are described, and are paired with their probable macroconch partners, T. (Emileites) malenotatus (Buckman) and E. (E.) subcadiconica Buckman respectively. The stratigraphic distribution of the main members of the subfamily Otoitinae in southern England shows that the two new species fill an important gap in our knowledge of this subfamily. In particular T. (T.) cricki is of fundamental importance, as it is the undoubted ancestor to both Emileia and Frogdenites and possibly also Pseudotoites. With their restricted stratigraphic range and wide geographic distribution, these new species are valuable stratigraphic indices for delimiting the base of the ovalis Subzone of the laeviuscula Zone. The most important exposures of the ovalis Subzone are discussed and the famous fauna described from the south of France by Douville is revised.