Fig. 5
Chondrification sequence of 23 chondrocranial elements in all ten birds and their reconstructed consensus line (Neornithes). The chondrocranial characters are ordered chronologically for Neornithes. The Y-axis shows the relative timing of chondrification in which “0” represents the appearance of the first cartilage in the chondrocranium and “1” the appearance of the last one. Some chondrification events have not been described for certain species, resulting in gaps in the sequences shown