Fig. (3) .

Two highly pruned phylogenetic trees showing four taxic homologies (gill arches, jaws, lungs, swimbladders) and two transformational relationships between taxic homologies. A. Phylogeny of Chordates, with two taxic homologies (gill arches and jaws) mapped. The hypothesized transformation of gill arches to jaws is shown by a red arrow. Evidence for this transformational hypothesis is from anatomy, histology, and gene expression. B. Phylogeny of bony vertebrates with two taxic homologies (lungs and swimbladder) mapped. The hypothesized transformation of lungs to swimbladder is shown by a red arrow. Evidence for this transformational hypothesis is from anatomy, histology, and gene expression.