Which two types of organisms both survived the mass extinction that occurred at the end of the Permian Period?

It is traditionally assumed that last of the dinosaurs became extinct 65.5 million years ago in the K-T Extinction Event.

Birds and birds alone are the direct decedents of dinosaurs. Other species commonly associated with dinosaurs such as the crocodilians evolved from more ancient ancestors of dinosaurs the archosaurs. Dinosaurs evolved after the crocodilians had already split of onto another branch of the evolutionary tree.

There is however growing support based on the fossil record that birds not only directly evolved from dinosaurs but are so similar in morphology that they are in fact dinosaurs in their own right.