Figure 1.

The history of the diversity of the marine animal families over the past 600 million years. The solid line connects 77 data points, each showing the total number of well-skeletonized families known from a particular geological epoch (each of whose duration is indicated by the width along the × -xis). The numbered arrows indicate the five recognized episodes of 'mass extinction'; the one labeled 3 is that which separates the Paleozoic from the Mesozoic, and the one labeled 5 is the one that ended the dinosaurs and ushered in our own era.

May BMC Biology 2012 10:106   doi:10.1186/1741-7007-10-106
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