寒武纪宽川铺生物群中球状胚胎化石表面刺状结构及其意义*

以宽川铺生物群中获取的磷酸盐化立体保存的胚胎化石为研究材料,对胚胎化石表面超微结构和内部解剖结构进行观察并对比分析。结果显示,大部分胚胎化石表面被一单层光滑卵膜结构所包裹,卵膜之下胚胎形态多样;刺状结构位于卵膜之下,为原生质胚胎分泌而成的保护层,出现在不同大小和不同类型的胚胎中。结果表明:1)单一依靠胚胎大小或者表面结构不能作为胚胎的分类依据;2)与现生海葵等动物胚胎表面微绒毛相似,Olivooides表面刺状结构可能具有保护胚胎和生态扩散的功能;3)带刺Olivooides很可能发育成为动物演化早期最简单的带刺幼虫形式,是动物间接发育的证据。

THE STELLATE CUTICLE OF EMBRYO FOSSILS FROM LOWER CAMBRIAN KUANCHUANPU FORMATION

Embryos are preserved in 3D as phosphatized permineralizations with superficial structures,and interior anatomy revealed in partly decayed embryos.Different species share a similar naked egg membrane and stellate cuticle which indicate that:1)It is improper to judge affinity by size or superficial structure of embryos; 2) It is postulated that the stellate cuticle would provide physical protection and dispersal to suitable habitat.Such properties were also observed in extant sea anemone embryos;3) The stellate Olivooidesmay grow into a primitive larva,which could be the evidence of indirect development.