定日葉蛤

定日葉蛤（Tancredia? dingriensis (Wen)）是採集於藏南地區崗巴群的岩石標本。

基本介紹

• 中文名：定日葉蛤
• 外文名：Tancredia? dingriensis (Wen)
• 產地：藏南地區崗巴群
• 保存單位： 中國科學院南京地質古生物研究所

特徵描述

shell medium to slightly large, horizontally subelliptical, equivalve, inequilateral, weakly convex. umbo pointed, prosoclinic, placed at about 2/5 of shell length behind anterior extremity. posterior umbonal carina rounded, extending from umbo to upper part of posterior margin. escutcheon narrow, long, forming a right angle with main surface. cardinal formula as 3a 3b/2 4b; 2 large, triangular, high prominent, bending upward at extremity; 4b small, low, laminal backward oblique; 3a and 3b all laminal, separately forward and backward oblique. one anterior lateral on each valve; posterior lateral poorly developed, only one cast seen on a right internal mold. opisthodetic, ligamental area somewhat broad, behind 4b. anterior adductor scar vertically ovate, smaller than circular posterior one; they separately placed near extremities. pallial sinus rounded, moderately deep.

主要用途

地層劃分與對比。