Chordata

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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)
Dinosauria: 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.


Subphylum Urochordata (Tunicata)
    Class Ascidiacea
    Class Thaliacea
    Class Appendicularia or Larvacea
Subphylum Cephalochordata
    Class Cephalochordata or Acraniata or Leptocardia (Lancets)
Subphylum Vertebrata
  Superclass Agnatha ("Without jaws")
    Class Ostracodermi
    Class Cyclostomata
    Class Myxini
    Class Cephalaspidomorpha
  Superclass Gnathostomata ("Jawed mouth")
    Class Placodermi (an extinct fish)
    Class Chondrichthyes (cartilaginous fishes)
    Class Osteichthyes (bony fishes)
    Class Amphibia or Anamnia (amphibians)
    Class Reptilia (reptiles)
    Class Aves or Sauropsida (birds)
    Class Mammalia (mammals)