八臂仙母虫(Eoandromeda octobrachiata)与早期动物演化

独特的八辐射动物化石——八臂仙母虫(Eoandromeda octobrachiata)新记录被推断为原始的栉水母动物,在华南震旦系陡山沱组和南澳大利亚伊迪卡拉生物群产地均有发现,不仅为相关地层的国际对比架起了桥梁,而且将栉水母动物的最早化石记录推前了大约30Ma,并可能重塑动物系统树,原始的性状特征(如:栉板、栉板带、管状辐射臂、中央环带和八辐射螺旋对称性等)可以把栉水母动物定位在动物系统树更为原始的位置上,使我国后生动物起源和早期演化研究再次获得突破性进展,为破解早期动物演化之谜提供了化石方面的新证据,也与分子生物学研究的最新成果基本吻合。

Eoandromeda Octobrachiata and the Evolution of Early Animals

Recent records of the eight-armed Ediacaran fossil Eoandromeda octobrachiata, preserved in contrasting taphonomic windows from the southern China and Australia, have led to its interpretation as an early ctenophore (comb jelly). These early macrofossil records have not only presented a link between the Sinian Doushantuo Fomation and the relevant strata of the classic Ediacara biota in Australia, but also extended the appearance date of Ctenophora backwards by approximately thirty millions years. Moreover, newly discoveries would reorder the earliest branches in the animal tree. The diagnostic features (i.e.: ctenes/comb plates, comb rows, tubular arms, central ring and spiral octoradial symmetry, etc.) suggest that Eoandromeda belongs to the stem lineage of the clade that includes modern ocean dwellers known as comb jellies. The recent paleontological study is consistent with a recently published molecular phylogenomic hypothesis. It advances the research of metazoan origin and early evolution, and helps solve the puzzle of early animal evolution by using the new fossil evidence.