What Actually Died Off at the Great Dying?

Whenever one reads about the mass extinction events, the high benchmark is always the Permian-Triassic extinction event, when supposedly over 90% of all speices died off. And I won’t doubt that that figure is accurate.

But one would think that that would mean that at least a reasonable proportion of higher taxa went extinct as well. And frankly, I’m not seeing that in the (textbook-level) literature.

Okay, brachiopods got reduced from a major component of the seafloor fauna to a very minor one. But they survived. Trilobites and acanthodians (‘spiny sharks’) died out during the Permian – but well before its end, and both were groups in decline – much as if the tuatara died out today: a whole order would die out with it, but outside New Zealand it would be noticeable only to people interested in such stuff, kind of a ‘celebrity death pool’ item. Several lineages of amphibians died out – but their relatives survived into and dominated the early Triassic.

So what actually died off in the Great Dying?

Lots, if you check with Wikipedia: http://en.wikipedia.org/wiki/Permian–Triassic_extinction_event#Extinction_patterns

Even among those families and orders that survived, large numbers of genera and species were wiped out. Snails, for example, had a 98% reduction in the number of genera (from the above link).

That’s a nice summary, Dervorin, and it brings together a lot of what I’d seen before. The point is that, by and large, it was “most of X, Y, and Z, died out, and the survivors re-radiated”. along with “M and N died out during the Permian but either (a) had been in decline, with only a couple genera surviving, or (b) may have died out before the P-Tr event, or © both.” The blastoids are a notable exception I hadn’t remembered – that’s a whole class of echinoderm that died out.

Thanks for the link, though.