The sternum, or breast bone, anchors the muscles that allow you to forcefully bring your arms together in front of you.
In the evolution of birds, the sternum became larger.
Look at the cladogram for a rough comparison of sternum size relative to body size. (Paleontologists have never found a Coelophysis fossil with a sternum.)
When did the enlarged sternum appear in the dinosaur lineage?
Map it on the cladogram.
Click on the next trait to look at the evolution of the wrist bone.
Oops!
Look for the lineage before the common ancestor to Velociraptor and other Maniraptorans!
Try again.
