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Fossil embryo
Fossil embryos are the preserved remains of organisms that have yet to hatch or be born. Many fossils of the Doushantuo formation have been interpreted as embryos; embryos are also common throughout the Cambrian fossil record.
==Preservation==
Taphonomic studies indicate that embryos are preserved for longest in reducing, anoxic conditions. These conditions can keep the embryos intact for long enough for bacteria to mineralise the cells and permit their preservation.〔 However, phosphatisation was very rapid in the Doushantuo, so it is possible that faster preservation allowed embryos in different regimes to be preserved.
Preservation is mediated by bacterial biofilms. The cells of the embryo break down within hours of their death, under the effect of its own enzymes. Bacteria invade the decaying embryo before its cells can collapse, and biofilms take on and preserve the three-dimensional structure of the cells. The activity of these bacteria promote mineralisation.〔
Currently, only fossils representing very early stages in embryonic development have been preserved - no embryos have been interpreted as having undergone a large number cleavage stages.〔
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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