Early animal evolution: emerging views from comparative biology and geology.

@article{Knoll1999EarlyAE,
  title={Early animal evolution: emerging views from comparative biology and geology.},
  author={Andrew H. Knoll and Sean B. Carroll},
  journal={Science},
  year={1999},
  volume={284 5423},
  pages={
          2129-37
        }
}
The Cambrian appearance of fossils representing diverse phyla has long inspired hypotheses about possible genetic or environmental catalysts of early animal evolution. Only recently, however, have data begun to emerge that can resolve the sequence of genetic and morphological innovations, environmental events, and ecological interactions that collectively shaped Cambrian evolution. Assembly of the modern genetic tool kit for development and the initial divergence of major animal clades occurred… 
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