An animal with vertebrae made from either cartilage or bone is a vertebrate. Vertebrates can be mammals, fish, birds, reptiles or amphibians.
Vertebrates all have a stiff vertebral column running down their bodies, and this column is made up of a series of discs and vertebrae to support the animal structurally and to lend it a certain amount of flexibility.
Scientists think that vertebrates first emerged during the Cambrian period, which was around 525 million years ago. The first known vertebrate is considered to be an animal known as Myllokunmingia, which had a skull and skeleton that was made up of cartilage.