重庆合川地区中二叠世晚期腕足动物多样性演变

利用重庆合川地区茅口组地层中的腕足动物化石进行了物种多样性演变的统计分析，从分析的结果可以发现，本地区前乐平世事件发生在中二叠世晚期。根据腕足类物种多样性综合指数的变化规律，以及地层中腕足类属中的演变过程，可以看出前乐平世事件在本区由两期组成：第一期属、种灭绝率分别为42.9%和60%，第二期属、种灭绝率分别为42.9%和66.7%。在两次灭绝前，还出现了二次物种多样性辐射过程：第一次物种新现率为75%,第二次物种新现率为77.8%,无论是灭绝还是辐射，其规模均是第二次大于第一次。

Evolution of Brachiopod Diversity of the Late Middle Permian in the Hechuan Area of Chongqing

Analysis of the evolution of species diversity based on brachiopod fossils of the Maokou Formation strata in the Hechuan area in Chongqing city indicates that the Lopingian Epoch incident in this region occurrs in the Late Permian.According to the integrated index of brachiopod species diversity and the brachiopods evolutionary process,this paper concludes that the Lopingian Epoch incident in this region is composed of two phases.In the first phase,genus extinction rate was 42.9% and the species extinction rate was 60%.Rates of the second phase were 42.9% and 66.7% respectively.Before the both extinctions,two courses of expansion in species diversity occurred,and the coming probability of new species in the first course was 75%.Probability of new species in the second course was 77.8%.Whether the species were extinct or radiant,the rate of the second was higher than that of the first time.