Vertebrates animals

Anatomy and morphology
One characteristic of the subphylum are that all members have muscular systems that mostly consist of paired masses, as well as a central nervous system which is partly located inside the backbone (if one is present). The defining characteristic of a vertebrate is considered the backbone or spinal cord, a brain case, and an internal skeleton, but the latter do not hold true for lampreys, and the former is arguably present in some other chordates. Rather, all vertebrates are most easily distinguished from all other chordates by having a clearly identifiable head, that is, sensory organs – especially eyes are concentrated at the fore end of the body and there is pronounced cephalization. Compare the lancelets which have a mouth but not a well-developed head, and have light-sensitive areas along their entire back.

Evolutionary history
Vertebrates originated about 500 million years ago during the Cambrian explosion, which is part of the Cambrian period. The earliest known vertebrate is Myllokunmingia. According to recent molecular analysis Myxini (hagfish) also belong to Vertebrates. Others consider them a sister group of Vertebrates in the common taxon of Craniata

Here you can find some vertebrates animals, they're going to tell you about their Bone System