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''Heteroceras'' is a Lower Cretaceous heteromorph ammonite belonging to the ancyloceratacian family, Heteroceratidae, characterized by a helically coiled juvenile shell at the apex followed by slightly curved adult shaft, with a J-shaped section at the end of it. The shell is ribbed; ribs are concave and oblique on the helix, straight and transverse on the later stages. ''Heteroceras'' has been found in France, central Europe, the Caucasus, and Peru. Related genera are ''Hemibaculites'' and ''Cochidites''. The family, Heteroceratidae, is a derivative of the Ancyloceratidae. ==References== * Arkell, ''et al'' 1957. Mesozoic Ammonoidea. Treatise on Invertebrate Paleontology, Part L, Ammonoidea. Geological Society of America and Univ. Kansas Press. * (Heteroceraras- Paleodb ) * ''For illustrations see'' (Genre Heteroceras, Orbigny 1850 ) 抄文引用元・出典: フリー百科事典『 ウィキペディア(Wikipedia)』 ■ウィキペディアで「Heteroceras」の詳細全文を読む スポンサード リンク
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