广泛分布的寒武纪最早期(梅树村期)地层中,普遍发现以软舌螺为主的有壳生物及其它一些生物类群组成的动物群——梅树村动物群,这是具硬壳的节肢动物出现之前无三叶虫带中的特殊生物类群,也是地史中首次出现的带壳生物。以其最老组合出现作为寒武纪的开始,具有较重要的意义。 Among the widely distributed Cambrian early (Meishucun period) strata, the fauna of the Meishu village, the shellfish and other biota, are found predominantly in the genus Soft-shelled turtle Before the advent of shell arthropods there was no special group of organisms in the trilobite belt, but also for the first time in the history of shelled creatures. With its oldest combination as the beginning of the Cambrian, it is of more significance.