全球早、中寒武世藻类生物地理分区初探

澄江生物群、凯里生物群、加拿大布尔吉斯生物群和西伯利亚藻群中均有丰富的藻类化石。根据前寒武纪宏观藻类的分布以及凯里生物群和布尔吉斯页岩生物群中藻类和后生动物的相似性，讨论了前寒武纪至中寒武世期间生物地理分区的控制因素。对几个生物群中的藻类化石和后生动物化石的对比研究发现,在相近的纬度范围内, 动植物化石组合特征非常相似; 而纬度明显差异时, 藻类生物群及后生动物群也具有明显的差异。由于后生生物在前寒武纪至中寒武世期间具有低的演化程度和分异能力，因此生物地理分布的主要控制因素是古纬度。而Schopf (1976)的生物地理分区模式不适合这一时期的生物地理分区。结合前寒武纪至中寒武世后生生物化石的分布情况，建立了前寒武纪-中寒武世时期的生物地理分区模式。这个模式较好地解释了分布在北美大陆和华南大陆上的寒武纪生物群相似的原因。

STUDY ON GLOBAL DISTRIBUTION OF ALGAE BIOGEOGRAPHIC BIOTA IN EARLY AND MIDDLE CAMBRIAN

Abundant and well preserved Cambrian macroalgal fossils occured in the Chengjiang Biota, Kaili Biota, Burgess Shale Biota and Siberian flora Based on the patterns of geographic distributions of the Precambrian macroalgae, and the similarities to both algae and Metazoan fossils in the Kaili Biota and the Burgess Shale, the factors controlling the biogeographic provincialization of the interval of the Precambrian Middle Cambrian are discussed Comparing algae and Metazoan of the Kaili biota with those of the Burgess Shale and the Siberian flora, we discover that the regions of the same palaeolatitude present the similar bioassemblage, while the regions of distinct different palaeolatitude present obviously different bioassemblage Because evolutional level of Metazoan is low in the Precambrian Middle Cambrian and biotic diversifying energy is low, the main factor controlling the provincialization of the Precambrian Middle Cambrian biogeography is palaeolatitude The Schopf's model of biogeographic region is not suitable for Metazoan on the basis of the patterns of geographic distribution of Metazoan in the Precambrian Cambrian A new model for dividing the Precambrian Middle Cambrian biogeographic regions is established in this paper The model could explain the similarities among the composition of the Chengjiang Biota, Kaili Biota and Burgess Shale Biota