Vertebrate is any animal with a backbone. In this example, vertebrates are classified based on series of visible characteristics. If it has fur then it is classified as mammal else they are grouped based on feathers. If it has feathers then it is classified as bird else they are grouped based on dry skin. If it has dry skin then it is classified as Reptile else divide the group based on scales. If it has scales it is classified under fishes else classified under Amphibians.