Birds, reptiles, amphibians, mammals and fish all have a notochord, a post anal tail, pharyngeal slits and a dorsal nerve cord at some point of development. They belong to subphylum vertebrata in phylum chordata.
This category of animals is the most highly evolved and most complex. They have bilateral symmetry and an internal skeleton of cartilage or bone. A nervous system at the back divides into the spinal cord and the brain, and most possess two pairs of limbs. In human beings, the limbs are the legs and the arms, while in birds, they are the legs and the wings.
All the animals ingest food through the mouth, are either cold blooded or warm blooded, take in oxygen and eliminate carbon (IV) oxide through gills or lungs and reproduce sexually. These groups of animals are either aquatic and live in water, or are terrestrial and live on land. Fish are fully aquatic and cannot survive outside water. Amphibians live on land but reproduce in water. Reptiles, birds and mammals can be aquatic or terrestrial.
In terms of evolutionary origin, fish evolved first, followed by amphibians, reptiles, birds and then mammals. The most advanced of these groups of animals are the mammals. Human beings, the most advanced organisms in the animal kingdom, are mammals.