Life’s “Second Big Bang”

The moderately scientific literate amongst my readership (which is probably most of you) have heard of the “Cambrian Explosion”, the massive diversity and proliferation of life 540 million years ago. I first came across the idea 25 years ago, thanks to the late Carl Sagan.
Did you know that, 489 million years ago, after a die off of a lot of that diversity, there was a second proliferation, an Ordovician flowering?
“By the end of the Ordovician, biodiversity had reached a level that would not be surpassed for another 200 million years. Look along the shoreline today and chances are you will find creatures that first appeared in the Ordovician, including starfish, sea urchins, oysters and scallops.”