Answer to Question #183847 in Evolution for Grace

Question

Alligators, dinosaurs, mammals, and birds are all more closely related to one another than any of these species are to turtles, according to the evidence. If we want taxonomic classes to represent ancestral relationships - with all members of a group sharing a shared ancestor and the group containing all descendants of that common ancestor - how do we revise vertebrate classification?

Answer 1

Vertebrates can be subdivided into five major groups: fishes, amphibians, reptiles, birds, and mammals. Amphibians, reptiles, birds, and mammals are ranked as classes. 

Amphibians, reptiles, mammals, and birds evolved after fish. According to the order of evolution, the first amphibians evolved from a lobe-finned fish ancestor about 365 million years ago. They were the first vertebrates to live on land, but they had to return to water to reproduce.

Close linkages to vertebrate evolution makes evolutionists classify organisms like the mammals, and birds, dinosaurs to their close linkages in evolution.