Evolution of a Core Gene Network for Skeletogenesis in Chordates
Figure 2
Overview of the Runt gene evolution in chordates.
The stepwise evolution of cartilage and bone and the most likely time intervals of Runt gene duplications (Dup) are indicated. The position of tunicates is contentious [31] which is indicated by a dashed line. In this context it is of interest that pre-neural crest cells have been observed in tunicates [60].