I've being reading in the New Scientist about the (rather romantically named) Opposite Birds. These evolved from dinosaurs at about the same time as the ancestors of modern birds and coexisted with them for millions of years. They had feathers and must have been good fliers.

Then came the mass extinction of 65 mya. Of all the dinosaurs only modern birds survived. You might have thought that being so similar the Opposite Birds would have lived on too. Mysteriously they didn't and it's quite hard to understand why.

Here's a rather nice reconstruction of an opposite bird. If you look closely you'll see it has teeth.

https://commons.wikimedia.org/wiki/File:Shanweiniao_cooperorum.jpg