摘要
Based on more exquisitely preserved specimens of Markuelia hunanensis recently recovered from Middle and Upper Cambrian in western Hunan and in the light of Synchrotron radiation X-ray tomo-graphic microscopy, the developmental sequence from cleavage through organogenesis to the pre-hatching of Cambrian embryo Markuelia, especially the developmental sequence during the pre-hatching stage, i.e. from the earliest period when the scalids and tail spines only took shape to the latest period (just about hatching), is established. This developmental sequence provides a pattern of embryonic development during the pre-hatching stage, which has not been established in the living scalidophorans (priapulids, loriciferans and kinorhynchs). Thus, it not only enriches our knowledge on the embryonic development of the extant descendants of Markuelia, but also opens a new window to the evolution and development of the animal.
Based on more exquisitely preserved specimens of Markuelia hunanensis recently recovered from Middle and Upper Cambrian in western Hunan and in the light of Synchrotron radiation X-ray tomographic microscopy, the developmental sequence from cleavage through organogenesis to the pre-hatching of Cambrian embryo Markuelia, especially the developmental sequence during the pre-hatching stage, i.e. from the earliest period when the scalids and tail spines only took shape to the latest period （just about hatching）, is established. This developmental sequence provides a pattern of embryonic development during the pre-hatching stage, which has not been established in the living scalidophorans （priapulids, Ioriciferans and kinorhynchs）. Thus, it not only enriches our knowledge on the embryonic development of the extant descendants of Markuelia, but also opens a new window to the evolution and development of the animal.
基金
Supported by the National Natural Science Foundation of China (Grant Nos. 40572003 and 40372001)
the Research Fund for Doctoral Program of High Educa-tion (Grant Nos. 20060001059 and 2000000127)
Laboratory of Paleobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences (Grant No. 023106)
