''Cymaceras'' is a genus within the oppeliid subfamily Ochetoceratinae from the
Kimmeridgian
In the geologic timescale, the Kimmeridgian is an age in the Late Jurassic Epoch and a stage in the Upper Jurassic Series. It spans the time between 157.3 ± 1.0 Ma and 152.1 ± 0.9 Ma (million years ago). The Kimmeridgian follows the Oxfordian ...
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
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