Editing Paleozoic (section)

==Footnotes==
{{notelist|notes=

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The list of the "big 5" [[mass extinctions]] only counts extinctions in the [[Phanerozoic Eon]], since up to [[Ediacaran|the end of]] the [[Proterozoic Eon]], life was [[Ediacaran biota|all soft-bodied]]. The meagre [[Ediacaran biota|fossil traces of earlier life]] make it essentially impossible to identify [[species]] or [[genus|genera]], and it is the disappearance of large proportions of existing genera from the fossil record that is the standard for comparing [[extinction event]]s of the Phanerozoic "big 5". The one known [[extinction event]] in the [[eon (geology)|eons]] before the Phanerozoic was the '''[[Oxygen Catastrophe]]''', or the '''[[Great Oxygenation Event]]''', when the previously [[Anoxic waters|anoxic]] seas  were poisoned with [[oxygen]] by [[Evolution of photosynthesis|newly photosynthesizing bacteria]]. By some estimates, that event killed almost all life on the Earth, and might qualify as the "greatest ever" mass extinction, if its consequences for soft-bodied genera could be measured. Further, there might have been ''other'' extinction events in the [[precambrian]] eons, whose traces in the [[geologic record]] (if any) are less obvious than the [[Great Oxygenation Event|Oxygenation Event]].
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