Don’t forget pandas and raccoons—they have hands of a sort
Pandas, at least the giant variety, would be unlikely to survive a mass extinction. Their diet is so restricted and calorically limited, and their reproduction is so slow and inefficient, that they'd have died out long ago if they hadn't found themselves a cushy environment with abundant food and few threats. They're basically hothouse flowers, which is why they've been so critically endangered by the loss of much of their environment.
But then, land megafauna like elephants would be unlikely to survive a mass extinction either. As I said, it's the small, light-eating, quick-breeding species that bounce back best from drastic environmental change, which is why the birds and puny mammals came through the K-T extinction while the larger, non-avian dinosaurs died out.
Meanwhile, in the oceans, we've got octopus and squid, which seem to have highly sophisticated brains that may equal or surpass ours in some ways, but also have very short lifespans so that they don't have time to learn much or expand their capabilities much. Imagine a race of geniuses that all died before they could reach kindergarten -- all that wasted potential. It's kind of sad. But if they ever mutate in a way that lets them live longer, watch out. They not only have sharp, adaptable brains, but manipulative capability that makes our much-vaunted hands seem clumsy in comparison.
On the other hand, they're very different from intelligent vertebrates in that they aren't social by nature, so they might not be inclined to form any kind of civilization. But on the, err, third tentacle, they might be smart and pragmatic enough to see the mutual benefit of cooperation. Whether they'd have any empathy for the other species they shared the planet with, like us, would remain to be seen.
