It all starts with the invertebrate, the group with  no bakbone.With no backbone the animals are usally small and  slower and is the ( outgroup).Next, it is the vertebral column the animals who has a backbone.The advantage of having a backbone is a well deveopled skeleton.The animal that is next that animal (fish) has the advantage of gills,fins, and jaws. Better than the animal before them.Next, is the Salamander the (four legs) it evolves over time so the next speices has legs so they can walk on land and reproduce better than before.The turtles are next  (Amphibian) . They lay eggs that are fluid-filled eggs with hard shells before the species before it so it evolved.Next, is the mammals they have hair. The mammalsw are the only type of group that can carry fur or where it. To come to a conclusion all these animals have something in common, but each one has something that is very unique that makes up them.