通过对贵州瓮安新元古代陡山沱组瓮安微型球状化石SEM的观察，发现代表未分裂卵，和2、4、8、16不同分裂阶段的胚胎。这些未分裂的卵和处于不同发育阶段的胚胎化石不仅大小和卵壳表面装饰相同，而且它们均具明显的围卵腔和球形卵裂等特征，清楚表明这些卵和胚胎均为同一物种的产物。由于这些卵的表面装饰与现生某些甲壳类休眠卵极其相似，曾被解释为动物的休眠卵；当前不同卵裂阶段胚胎的发现表明它们不是休眠卵，而是处于发育过程的卵。围卵腔不仅是现生两侧对称动物早期胚胎的常见构造，而且具围卵腔构造的未分裂卵和不同卵裂阶段的胚胎化石在瓮安动物群也十分常见。除了以上具表面装饰胚胎化石的大量发现外，文中还报道围卵腔构造在表面光滑胚胎化石中的发现。这些具围卵腔结构的胚胎化石主要为两侧对称动物的胚胎。

Here we report the finding of eggs in 2 cell, 4 cell, 8 cell and 16 cell cleavage stages from Precambrian Doushantuo Formation, Weng'an, central Guizhou (Southern China). These eggs bearing a number of shared features suggest that they were derived from early animal belonging to the same species. These features include:same size; egg shell ornamented with identical structure; presence of perivitelline space; and equally holoblastic cleavage with spherical early cleavage cells. The identical eggs have been described as animal resting eggs by some authors and the presence of different cleavage stages indicates that they were developing eggs. Therefore, the resemblance with the resting eggs of some modern crustaceous forms in egg shell ornamentation can not be taken as a sign for their affinity. The perivitelline space mainly occurs in the eggs of modern bilaterians. The occurrence of the perivitelline space from 580 million years old eggs indicates that bilaterians might have evolved in a deeper time before Cambrian explosion.

Q915.6

国家自然科学基金 (No .40 13 2 0 10 )资助课题