Chordata

Gnathostomata - Philippe Janvier's article about the jawed vertebrates in the Tree of Life website.
http://ag.arizona.edu/ENTO/tree/eukaryotes/animals/chordata/gnathostomata.html

North American Wildlife - Includes photographs and information on a wide range of mammals and reptiles from Canada, the United States and Mexico. Includes fact sheets and distribution maps.
http://www.wildlifenorthamerica.com/

Phylum Hemichordata, Urochordata and Cephalochordata - Illustrated description of these three phyla, and the three classes within Urochordata. Also information on the larval stages, when they form part of the plankton. [PDF]
http://www.mba.ac.uk/nmbl/publications/occpub/guide/section17.pdf

Chordata - Overview of the taxonomy of Phylum Chordata, which includes the well-known vertebrates (fishes, amphibians, reptiles, birds, mammals), hagfishes, tunicates, and lancelets.
http://tolweb.org/tree?group=Chordata&contgroup=Animals

Vertebrata - Introduction to the vertebrates and their classification, including the Hyperoartia, or lampreys, and the Gnathostomata, or jawed vertebrates.
http://tolweb.org/tree?group=Vertebrata&contgroup=Craniata

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.
http://animaldiversity.ummz.umich.edu/chordata.html

Database of Vertebrates and Centres of Vertebrate Diversity in Mozambique - The Database includes almost 3500 vertebrate species, taxonomic information, English, Portuguese and vernacular names, conservation status and numerous maps illustrating biodiversity hotspots and locations of endemic species.
http://www.fzi.uni-freiburg.de/VertebratesMOC/

Subphylum Vertebrata - What makes a vertebrate a vertebrate? They have more in common than a backbone. Find out more from the Animal Diversity Web.
http://animaldiversity.ummz.umich.edu/vertebrata.html