When we took the fin of Tiktaalik apart, we found something truly remarkable: all the joint surfaces were extremely well preserved. Tiktaalik has a shoulder, elbow, and wrist composed of the same bones as an upper arm, forearm, and wrist in a human. When we study the structure of these joints to assess how one bone moves against another, we see that Tiktaalik was specialized for a rather extraordinary function: it was capable of doing push-ups.
