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

早奥陶世礁生态系统发生了一次体制转换，对随后的礁演化产生了重大影响。本文研究了扬子地台生物礁组分的时间变化及其建造模式。下奥陶统（Tremadocian）苔藓虫。pelmatozoic礁and demosponge海绵.苔藓虫珊瑚礁是世界上最古老的藻类占主导地位的苔藓虫珊瑚礁，而demosponge。叠层石礁是体制转换前时期的残留物。生态系统中主要造礁者的戏剧性更替很可能与奥陶纪辐射达到顶峰的海洋地质生物群的渐进革命密切相关。

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.