Ordovician-Silurian Mass Extinction
Death by Air
Published in The EarthSphere Blog
Prologue
The last two posts in the Forgotten Origins series looked at the Ordovician Period. But all good things come to an end, and the end of the Ordovician was a catastrophe.
A Lesson Worth Learning
The Ordovician Period was a great time for life on Earth until it wasn’t. The biosphere was reminded of a biblical adage as it applies to mother nature “she giveth and she taketh away.” The official end of the Ordovician clocks in at 443.8 million years ago, but the catastrophe started about a million years earlier. It lasted for 4 million years, extending into the beginning of the Silurian Period. In the beginning, the changes probably seemed like minor perturbations in the environmental status quo, but by the end, 85 percent of Ordovician species had disappeared into the void of extinction. Perhaps there is a lesson for Anthropocene climate change deniers and agnostics in this ancient event.
Four million years is a long time, and the progressing extinction came in pluses. The earliest casualties appeared as many of the graptolites, brachiopods, and trilobites faded away. Dropping seal levels signaled the onset of phase two as water drained from the shallow seas, destroying the…
