Well, actually, no.
I’m assuming “proceeded” was intended to be “preceded.”
The point Jimpy was making, IMHO, was that in the couple of geological epochs prior to a mass extinction event, the number of species declined. I.e., a bunch of dinosaurs trucking along at, say, 90 species (these numbers are artificial, because I don’t have my references) through most of the Cretaceous, along comes the Belly River stage and they drop to 84, then the Lance and they drop off to 75. Then comes the K-T event, and all the remaining 75 die off.
Same thing happened at the Permian-Triassic boundary for sure, and best evidence is that it did before the other, less dramatic mass extinction events too.
Put that way, does it become a more sensible, less apparently tautological statement?