江西玉山上奥陶统凯迪阶三衢山组的丛花海绵(Corymbospongia)*

串管海绵在中–晚奥陶世经历了的首次辐射演化事件, 在北美、新南威尔士、哈萨克斯坦、西伯利亚和中国西北等地的上奥陶统地层中皆有报道, 但研究程度较低。本文系华南奥陶系串管海绵首次系统古生物学的报道, 详细描述江西玉山上奥陶统凯迪阶三衢山组的Corymbospongia (丛花海绵属)化石, 并基于C. amplia Rigby, Karl, Blodgett & Baichtal, 2005和C. mica Rigby & Potter, 1986的标本展示该属化石外壁的微孔等特征性结构, 这2个种具有跨板块的生物地理分布。综合串管海绵产出层的碳酸盐岩微相以及伴生钙藻和珊瑚化石等群落分子的指相参照, 识别C. amplia和C. mica均具有明显的生态专属性: C. amplia为造礁生物, 在小型微生物岩中出现; C. mica则代表适应于更浅水生境的平地群落代表。本研究将为从底栖生物群落角度开展扬子区生物地层学及古地理重建提供进一步的依据。

Corymbospongia Rigby & Potter, 1986 from the Sanqushan Formation (Ka-tian, Upper Ordovician) in Yushan, Jiangxi

Sphinctozoan is one of the less studied macrofossils from the Ordovician. During the Middle and Late Or-dovician, sphinctozoan sponges experienced their first radiation. Sphinctozoan occurrences are known from Alaska andCalifornia of the United States, New South Wales of southeastern Australia, Kazakhstan, Siberia of Russia and north-western China. Here we provide the first report of Corymbospongia from the Sanqushan Formation (Katian, Upper Ordovician) in Yushan, Jiangxi, China. Furthermore, the main characteristics of C. amplia and C. mica are described in this paper, which also reports the diagnostic features of the chambers for the first time. Combined with the results of microfacies, calcareous algae and corals, the two species show different ecological preferences: C. amplia is an active reef builder, which helps to create framework in small patch reefs; C. mica tends to occur in shallow water habitats and is the representative in level-bottom community. Our results provide further evidence for biostratigraphic and palaeo-geographic reconstruction of South China based on the distribution of benthic fauna.