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''Ussuria'' is a Lower Triassic ammonite with a smooth, involute discoidal shell with submonophyllic sutures, belonging to the ceratitid family Ussuriidae. ''Ussuria'' has been found in Russia in Siberia (original discovery), China, Oman, and Idaho in the United States. ==Description== The shell of ''Ussuria'' is laterally compressed and involute. Whorls are deeply embracing, increasing rapidly in height. Umbilicus is narrow and deep with rounded shoulders. Sides gently convex, converging on a narrow rounded venter. Sutures are ammonitic, with digitate lobes and submonophyllic saddles. The external,(or ventral), lobe is divided by a broad digitate siphonal saddle with each side of the lobe deeply trifid. The two or three principal lateral lobes on either side that are wide and deeply digitate, followed dorsally by another three or more smaller, also digitate, auxiliary lobes. The first lateral saddle is typically indented only on the ventral (rim) side and the second lateral saddle only of the dorsal side. ''Ussuria'' somewhat resembles ''Sturia'', commonly placed in the Ptychitidae. The early growth stages of ''Ussuria'' are like ''Dimorphoceras'', the intermediate growth stage like ''Thalassoceras''. 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「Ussuria」の詳細全文を読む スポンサード リンク
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