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一、前言三角蛤科(TRIGONIIDAE)的化石,在世界各地中、新生代地层中广泛分布。它出现于中三迭世,到侏罗纪早期开始大量繁盛,以后几经兴衰,一直延续到现在。据统计,这
I. INTRODUCTION TRIGONIIDAE fossils are widely distributed in Mesozoic and Cenozoic strata all over the world. It appeared in the Middle Triassic and began to flourish in the early Jurassic. Afterwards, it rose and fell and has continued to the present day. According to statistics, this