ChordaTa

Classification

The traditional classification of vertebrates is a mess, with a wide variety of paraphyletic groups that have either been abandoned or extended (here marked B). Unfortunately, no particularly standard system has settled in to replace it; the problem is there have been too many adaptive radiations. For now, here is a minimal tree of living forms including most traditionally class-sized groups:

Urochordata

Cephalochordata

Craniata

Myxini (hagfish)

Vertebrata

Petromyzontiformes (lampreys)

Gnathostoma

Chondrichthyes (cartiligenous fish)

Osteichthyes B

Actinopterygii (ray-finned fish)

Sarcopterygii B

Coelocanthamorpha

Dipnoi (lungfish)

Tetrapoda

Lissamphibia (frogs, toads, salamanders)

Amniota

Mammalia

Chelonia (turtles)

Squamata (lizards, snakes)

Sphenodontida (tuataras)

Crocodylomorpha (crocodiles, alligators)

Aves (birds)

Information on characteristics of each group and a more detailed classification thereof should probably go under its headline - eg details of skeletal system and listing of jawless fishes under Vertebrata.