1. one of the grand divisions of the animal kingdom, comprising all animals that have a backbone composed of bony or cartilaginous vertebræ, together with Amphioxus in which the backbone is represented by a simple undivided notochord. the vertebrata always have a dorsal, or neural, cavity above the notochord or backbone, and a ventral, or visceral, cavity below it. the subdivisions or classes of vertebrata are mammalia, aves, reptilia, Amphibia, pisces, Marsipobranchia, and Leptocardia.

1. A phylum or prime division of the animal kingdom, containing all those animals which have a backbone or its equivalent; the vertebrates, formerly contrasted with all other animals (invertebrata), now ranked as one of seven or eight phyla which are severally contrasted with one another.

1. fishes; amphibians; reptiles; birds; mammals