鄂西地区下奥陶统分乡组生物群按其生态特征划分为３个生态组合，１０个化石群落或埋藏群：（１）壳相组合：Ｔｒｉｔｏｅｃｈｉａ－Ｐｅｌｍａｔｏｚａｎ群落、Ｔｒｉｔｏｅｃｈｉａ－Ｐｏｍａｔｏｔｒｅｍａ群落；（２）礁相组合：Ａｒｃｈａｅｏｓｃｙａｈｉａ群落、Ａｒ－ｃｈａｅｏｓｃｙｐｈｉａ－Ｃａｌａｔｈｉｕｍ群落、Ｂａｔｏｓｔｏｍａ－ｐｅｌｍａｔｏｘｏａｎ群落、Ｂａｔｏｓｔｏｍａ群落、Ｃａｌａｔｈｉｕｍ－蓝绿藻群落；（３）静水相组合：Ａｃａｎｔｈｏｇｒａｐｔｕｓ－Ｄｅｎｄｒｏｇｒａｐｔｕｓ群落、Ｎａｎｏｒｔｈｉｓ－Ｐｓｉｌｏｃｅｐｈａｌｉｎａ埋藏群、Ｙｉｃｈａｎｇｏｐｏｒａ？群落。它们之间随环境变化显示出由壳相组合→礁相组合→静水相组合→壳相、礁相组合的演化序列，造礁生物之间也存在着一定的演替和取代。群落演化特征反映了研究区分乡期至红花园期沉积环境演变过程是一个海水不断加深复又变浅的海侵—海退旋回，这与早奥陶世特马豆克晚期至阿伦尼格早期世界性海平面升降过程是完全一致的 According to their ecological characteristics, the Lower Ordovician biome in Western Hubei is divided into three ecological groups and 10 fossil communities or buried groups: (1) shell-and-shell assemblages: Tritoechia-Pelmatozan community, Tritoechia-Pomatotrema community; (2) ) Reef assemblages: Archaeoscyahia community, Ar-chaeoscyphia-Calathium community, Batostoma-pelmatoxoan community, Batostoma community and Calathium-blue-green algae community; (3) Sediment assemblages: Acanthograptus-Dendrograptus community, Nanorthis-Psilocephalina community, Community. Their evolutional relationships with the environment show that there are also some successions and displacements in the reef-building organisms from shell-facies assemblage → reef-facies assemblage → hydrostatic facies assemblage → shell-facies and reef-facies assemblages. The evolutionary characteristics of the community reflect that the evolution of the sedimentary environment from the period of the Loess Plateau to that of the Red Garden is a transgression-regressive cycle of seawater deepening and deepening, which is similar to that of Late Aztec Temasek to Alengnig Early world sea level rise and fall process is exactly the same