If you don’t mind doing a bit of reading, download the following pdf which has more info about the general area and a few more maps:
http://www.santos.com/library/aridzone.pdf
Here is a wonderful link with over 500 graphs, illustrations, photos, etc. of extinction events, asteroids, fossils, extinct creatures restored, etc. If you look at the first line, there is a great graph in blue which shows that while there have been about 5 or 6 major extinction events since the Cambrian, several had clusters of ongoing events both before and after.
The Devonian event at 360 mya, or the Ordovician-Silurian event of 400 mya, might fit the bill. I hope they can date them more closely soon. I can’t wait to go back and study those charts some more.