Salamander Offers Two Evolutionary Quandaries: Non-Homologous Development and an ORFan

Salamanders have their own way of doing things. For most animals, if an important body part, such as a limb, is lost, it is gone for good. But for salamanders, they just grow a new one. Also, salamanders use different embryonic development patterns. For example, their digits (fingers and toes for us humans) form in the wrong order -- going, essentially, in the wrong direction.

You can see this from a figure in a paper by Neil Shubin's group. In the figure, the numbers across the top show the...