Based on the stratigraphically well sorted material from Japan and southern Sakhalin, the ammonoid species belonging to the genus
Desmoceras are classified as follows in ascending order:
D. latidorsatum (Michelin) (Middle to mid-Upper Albian),
D. dawsoni shikokuense (Yabe and Shimizu) (Upper Albian),
D. kossmati Matsumoto (uppermost Albian-Lower Cenomanian),
D. japonicum Yabe (uppermost Albian-Cenomanian), and
D. ezoanum Matsumoto (mid-Upper Cenomanian-mid-Lower Turonian).
D. japonicum can be subdivided into the earlier and later subspecies.
D. poronaicum Yabe is a junior synonym of
D. japonicum. Despite the scarcely ornamented shell, each taxon can be defined by its own characters.
(Contributed by Tatsuro MATSUMOTO, M.J.A.)
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