A regime shift in the reef ecosystem on the Yangtze Platform : clues to deciphering a great revolution of the Ordovician geobiota

早奥陶世发生了礁生态系统的更迭，对随后的礁演化产生了重大影响。本文研究了扬子地台礁组成及其构造方式的时间变化。本地区下奥陶统（Tremadocian）苔藓虫。Pelmatozoan礁石和demosponge。苔藓虫礁是世界上最古老的以骨骼为主导的苔藓虫礁。叠层石礁是政权转变前的遗迹。在生态系统的主要礁石建造者中，一个戏剧性的替换很可能与海洋地生物群的渐进革命密切相关，这种革命在奥陶纪辐射中达到高潮。

A regime shift in the reef ecosystem occurred in the Early Ordovician and influenced greatly the ensuing reef evolution. This study examines the temporal changes in reef constituents and their modes of construction on the Yangtze Platform. In this region, Lower Ordovician(Tremadocian) bryozoan. pelmatozoan reef and demosponge. bryozoan reef are the oldest skeletal-dominant, bryozoan reefs worldwide, whereas demosponge. stromatolite reef is a remnant of the period before the regime shift. A dramatic replacement in the main reef builders of the ecosystem is likely to have been closely related to the progressive revolution in the marine geobiota that culminated in the Ordovician radiation.