From the Scientific American article. |
But seriously... pretty much from the beginning of the theropod lineage (even before T-rex and velociraptors), they've been gradually getting smaller (some of them small enough to survive the K-T impact), until we had a chickadee in place of a man-eating colossus. They kept the feathers, discovering they were good for gliding and (eventually) powered flight, and lost the teeth (something had to give).
Here's the Scientific American blog's recap of the paper (pointed out by today's 10,000 Birds post), for those like me who don't have a subscription and aren't at a university any more.
(cross-posted)