埃迪卡拉纪至寒武纪苗岭世刺细胞动物化石研究现状与展望

A comprehensive review of cnidarian fossils during Ediacaran to Cambrian Miaolingian

刺细胞动物是一类具有刺细胞的水生无脊椎动物,分布在世界各地的海洋和淡水中。作为后生动物最早分化出的一支,刺细胞动物对研究后生动物的起源和早期演化具有极其重要的意义,也为研究后生动物系统发育、地层对比和古地理恢复等方面提供了重要的科研线索。本文简要介绍了刺细胞动物早期(埃迪卡拉纪至寒武纪苗岭世)的化石记录和研究现状,将刺细胞动物的早期演化分为四个时期,分别为前寒武纪、寒武纪纽芬兰世、寒武纪第二世和寒武纪苗岭世,并对上述四个时期的刺细胞动物进行论述。目前的研究表明:1)前寒武纪的刺细胞动物化石记录虽然比较丰富,但充满争议,目前尚未有比较确切的刺细胞动物记录;2)寒武纪纽芬兰世如宽川铺生物群中保存了较多的刺细胞动物胚胎及发育序列化石,是研究刺细胞动物演化的重要窗口;3)寒武纪第二世,以澄江生物群为代表的布尔吉斯页岩型化石保存了软躯体的刺细胞动物。与此同时,在第二世中已经出现了最早的珊瑚化石记录;4)寒武纪苗岭世刺细胞动物主要以布尔吉斯页岩型化石保存(如布尔吉斯页岩生物群和凯里生物群),同时期在美国犹他州发现的刺细胞动物印痕化石表明了这个时期几乎所有的刺细胞动物大类已经出现。本文根据上述时期的研究,对今后刺细胞动物化石的研究提供一些建议和讨论。

Cnidaria is an invertebrate clade characteristic of cnidocyte living in the sea and freshwater around the world.Cnidarians play a key role in the origin and evolution of metazoan because of its earliest derived from metazoans.They provide an important clue in early evolutionary,phylogeny,stratigraphic correlation and paleoenvironment of metazoans.This paper gives a brief comprehensive review in early cnidarians fossil records during the Ediaracan to Middle Cambrian(Miaolingian)and divides four periods of early cnidarian evolution:Precambrian,Cambrian Terreneuvian,Cambrian series 2,and Cambrian Miaolingian.We have discussed these four periods and the current research shows that:1)Although the Precambrian cnidarian fossil record is relatively abundant,most of them existing are full of controversy.There is no reliable fossil record of cnidarians;2)many cnidarian embryos and developmental sequences preserved in the Cambrian Terreneuvian,such as Kuanchuanpu biota,which is an important window to study the evolution of cnidarians;3)Burgess shale-type Lagerst?tte like Chengjiang Biota of the Cambrian series 2 exists soft-body characters of cnidarians.Meanwhile,the earliest coral fossil record appeared in this period;4)the Cambrian Miaolingian fossil records of cnidarians were mainly preserved as Burgess shale-type Lagerst?tte(such as the Burgess shale biota and Kaili biota).Another place in Utah,USA in this period found credible cnidarian impression fossil indicates that almost all cnidarian taxa have appeared during the Miaolingian.Based on the research in the above periods,we propose some suggestions and discussions on the further research of the early cnidarian fossils.