Q. What are the six criteria used to build a complete evolutionary branch of vertebrates?
Dichotomy in each of the six following criteria builds the vertebrate evolutionary branch: absence of mandibles separates cyclostomes from others absence of limbs separates fishes from the remaining absence of osseous skeleton separates chondrichthian (cartilaginous) fishes from osteichthyes absence of impermeable skin separates amphibians from the terrestrial vertebrates absence of warm blood (homeothermic body) separates reptiles from birds and mammals absence of mammary glands and hair separates birds from mammals.