1. Phosphatized polar lobe-forming embryos from the Precambrian of southwest China.
- Author
-
Chen JY, Bottjer DJ, Davidson EH, Dornbos SQ, Gao X, Yang YH, Li CW, Li G, Wang XQ, Xian DC, Wu HJ, Hwu YK, and Tafforeau P
- Subjects
- Animals, Annelida embryology, Biological Evolution, Blastomeres cytology, China, Embryo, Nonmammalian cytology, Geologic Sediments, Mollusca embryology, Phosphates, Platyhelminths embryology, Embryo, Nonmammalian anatomy & histology, Embryonic Development, Fossils, Invertebrates embryology
- Abstract
In developing embryos of some extant spiralian animals, polar lobe formation is one of the symmetry-breaking mechanisms for segregation of maternal cytoplasmic substances to certain blastomeres and not others. Polar lobe formation leads to unique early cleavage morphologies that include trilobed, J-shaped, and five-lobed structures. Fossil embryos similar to modern lobeforming embryos are recognized from the Precambrian Doushantuo Formation phosphates, Weng'an, Guizhou Province, China. These embryos are abundant and form a developmental sequence comparable to different developing stages observed in lobe-forming embryos of extant spiralians. These data imply that lobe formation is an evolutionarily ancient process of embryonic specification.
- Published
- 2006
- Full Text
- View/download PDF