Chordata: Overview of the taxonomy of Phylum Chordata, which includes the well-known vertebrates (fishes, amphibians, reptiles, birds, mammals), hagfishes, tunicates, and lancelets.
Gnathostomata: Philippe Janvier's article about the jawed vertebrates in the Tree of Life website.
Phylum Chordata: Brief introduction to the chordates, defined as organisms that possess a structure called a notochord, at least during some part of their development. Includes links to information about subgroups and representative animals.
Subphylum Vertebrata: What makes a vertebrate a vertebrate? They have more in common than a backbone. Find out more in this site from the Animal Diversity Web.
Vertebrata: Introduction to the vertebrates and their classification, including the Hyperoartia, or lampreys, and the Gnathostomata, or jawed vertebrates.