Ochetoceratinae
The Ochetoceratinae is a subfamily within the Oppeliidae from the Upper Jurassic, shells of which are typically oxycones with a tricarinate venter and falcoid ribbing, commonly divided by a median lateral groove or fillet. The median (middle) keel is the tallest. The Ochetoceratinae may be polyphyletic, derived from both the Oppeliidae and Hecticoceratinae Hecticoceratinae is a subfamily of oppeliids from the Middle and Upper Jurassic typically with strong falcoid or falcate ribbing that covers whorl sides completely. Venters are usually keeled and may be tricarinate.Treatise on Invertebrate Paleo ... as suggested by differences in the included genera. Description The median lateral groove is well developed in ''Ochetoceras'' and ''Fehlmanites'', less discernible in ''Cymaceras'', but missing or difficult to make out in the other four. References *W.J. Arkell, et al. 1957 Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L. Geological Society of America ...
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Cymaceras
''Cymaceras'' is a genus within the oppeliid subfamily Ochetoceratinae from the Kimmeridgian stage, around the middle of the Upper Jurassic. ''Cymaceras'' is rather unusual in its wavy keel that leans alternatingly to one side then the other. Shells are involute, compressed, with a narrow venter and distinct inner and outer ribs, both sets of which are curved in a concave forward fashion. References

;Notes ;Bibliography W.J. Arkell, et al., 1957. Mesozoic Ammonoidea, Treatise on Invertebrate Paleongology, Part L. Geological Society of America and University of Kansas Press. Ammonitida Late Jurassic ammonites {{ammonite-stub ...
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