Of Birds and Thumbs
Limusaurus sheds light on one particularly contentious matter about the origin of birds: how the fingers in a dinosaur hand got transformed into the end of a wing. A bird wing starts out as a limb bud, inside of which tiny clusters of cartilage cells start to form. Eventually, these clusters stretch out into wrist and finger bones, which later fuse together to provide a bendable spar that can support flight feathers.
Read the whole article (has pictures and diagrams, too!)
Found by TapwaterJ, purveyor of useless neat stuff