My running theory is the End Permian happened because the trilobites were simply too powerful. They needed to be stoped and only the worst extinction event ever with endless lava flows... the Earth split like an open wound, hyper-canes crawling the surface like the red spot of Jupiter... only all that was enough to stop those remarkable arthropods.
We, on the other hand? We may well be flicked off of the Earth like a flea. By our own petard. Whatever a petard is.