The End Ordovician Extinction seems weird to paleontologists. There’s a lot of agreement on the earth cooling at the end of the Ordovician, right up to evidence of major glaciation and a harsh ice age, but there are serious suggestions that will boggle your mind.
Some of these serious suggestions are of extra-terrestrial origin:
- A nearby gamma ray burst. Preprints of source articles here, here, and here might be more fun.
- An asteroid break-up.
Either of these events could cause glaciation, but by different mechanisms. The L-chondritic parent body break-up and resulting increase in dust in fall to the earth definitely happened. The gamma ray burst is more speculative.
I’m tickled that meteor impact isn’t the only astronomical event that could have had a large effect on the earth’s biosphere.
The Palaeocast episode on the Great Ordovician Biodiversity Event is definitely worth listening to, even if it only touches on the end-Ordocician extinction, and does not speculate on causes.