Mutations in what cl of genes have probably been responsible for many of the changes .?

a Developmental genes- these regulate cell fate during embryogenesis and have enormous impact in the relative body proportions. Hox and other master regulatory genes control timing and placement of limbs and organs as they grow. This is why logy is so obvious in related organisms. By regulating when and where structural proteins are expressed and used the basic body can be reproportioned into a different body plan. Limbs can be wings or legs or fins.