變化並準無窗貝

變化並準無窗貝是產於廣西壯族自治區來賓市象州縣中平鎮的泥盆紀(D)的化石。

基本介紹

• 中文名：變化並準無窗貝
• 外文名：Parathyrisina transitoria Chen et al., 1999
• 產地：來賓市象州縣中平鎮
• 形成時代：泥盆紀(D)

特性描述

this species displays the following features during its ontogeny:①the langer the shells,the greater convexity of the valves;②the finer the plications become;③the first pair of plications on both sides of fold or sulcus are much stronger than the plications on the lateral slope in small specimens,but become essentially equal to other plication on larger specimens;④most plications do not bifurcate of occasionally bifurcate anteriorly on small specimens (bifurcating about mid-length on large specimens).continuity of variation throughout the collection indicates that only a single but very variable species is involved.this species differs from the p.ganxiensis in its greater width;length nadio,its 5~7 plications on each flank.

化石產地

該化石產地為來賓市象州縣中平鎮。