Английская Википедия:Distichoceras
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Distichoceras is a member of the Haploceratacean family, Oppeliidae, and type genus for the subfamily Distichoceratinae, found in upper Middle and lower Upper Jurassic sediments in Europe,[1] Algeria, India, and Madagascar. The shell is essentially evolute and compressed with the outer flanks converging on a narrow, keeled venter; inner flanks which may be feebly ribbed, are separated from outer by a shallow spiral groove or band. Ribs on outer flanks end on or are looped to tall clavi (elongate tubercles or nodes) that line the venter, standing above the keel.
References
- Arkell et al., 1957. Mesozoic Ammonoidea, Treatise on Invertebrate Paleontology Part L. Geological Soc. of America and Univ Kansas Press. p. L279.
