The seven kingdoms

The white rectangles indicate kingdoms that did leave modern descendants, while the grey frames are for extinct kingdoms. 

In order to have a less biased reconstruction of the early history of life, the data from molecular phylogenies must be integrated by theoretical considerations. Those data are absolutely necessary - no doubt about that - but we should not forget that they are not sufficient. The history of life on Earth does not coincide with the history of the molecules that have survived, as if extinct kingdoms never existed. Molecules, therefore, take us back in time but only to a certain point. Beyond that, only geology and our theories can make the journey. 

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Figure 6.3 Schematic evolution of the seven kingdoms of life in seven stages.

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