New answers tagged taxonomy
In my view, we simply don't have good enough data to answer this question. The fossil evidence is too sparse prior to the Cambrian and the evidence that we do have suggests that the phyla were already too separated. Meanwhile, the depth of time and the different lifecycles and circumstances of the species involved mean that any "genetic clocks" we might use ...
As far as I know there is no phylum which appeared after the Cambrian. Every discussion beyond that is close to speculation, as the divergence estimates of different studies vary significantly. You might want to look into one of the resources mentioned below: http://www.timetree.org/index.php http://www.onezoom.org/
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