Fossil range: mid Early Cambrian to Recent
Northern bluefin tuna, Thunnus thynnus
|Classes and Clades|
Anatomy and morphologyCharacteristics of the subphylum are a muscular system that mostly consists of paired masses, as well as a central nervous system which is partly located inside the backbone (if one is present). The defining characteristic of a vertebrate is considered the backbone or spinal cord, a brain case, and an internal skeleton, but the latter do not hold true for lampreys, and the former is arguably present in some other chordates. Rather, all vertebrates are most easily distinguished from all other chordates by having an unequivocal head, that is, sensory organs - especially eyes are concentrated at the fore end of the body and there is pronounced cephalization. Compare the lancelets which have a mouth but no true head, and "see" with their entire back.
Ecology and life history
Evolutionary historyVertebrates started to evolve about 530 million years ago during the Cambrian explosion, which is part of the Cambrian period (first known vertebrate is Myllokunmingia). According to recent molecular analysis Myxini (hagfish) also belong to Vertebrates. Others consider them a sister group of Vertebrates in the common taxon of Craniata.
Taxonomy and classificationClassification after Janvier (1981, 1997), Shu et al. (2003), and Benton (2004).
- Subphylum Vertebrata
- (Unranked group) Hyperoartia (lampreys)
- Class †Conodonta
- Subclass †Pteraspidomorphi
- Class †Thelodonti
- Class †Anaspida
- Class †Galeaspida
- Class †Pituriaspida
- Class †Osteostraci
- Infraphylum Gnathostomata (jawed vertebrates)
- ::* Class †Placodermi (Paleozoic armoured forms)
- ::* Class Chondrichthyes (cartilaginous fish)
- ::* Class †Acanthodii (Paleozoic "spiny sharks")
- :* Superclass Osteichthyes (bony fish)
- ::* Class Actinopterygii (ray-finned fish)
- ::* Class Sarcopterygii (lobe-finned fish)
- :::* Subclass Dipnoi (lungfish)
- :::* Subclass Tetrapodomorpha (ancestral to tetrapods)
- :* Superclass Tetrapoda (four-limbed vertebrates)
- :::* Class Amphibia (amphibians)
- ::* Series Amniota (amniotic embryo)
- :::* Class Sauropsida (reptiles and birds)
- ::::* Class Aves (birds)
- :::* Class Synapsida (mammal-like reptiles)
- ::::* Class Mammalia (mammals)
EtymologyTheir name derives from the bones of the spinal column (or vertebral column), the vertebrae.
- Kardong, Kenneth V. (1998). Vertebrates: Comparative Anatomy, Function, Evolution, second edition, USA: McGraw-Hill, 747 pp.. ISBN 0-07-115356-X/0-697-28654-1.McGraw-Hill&rft.place=USA&rft.pages=747%20pp.&rft.isbn=0-07-115356-X/0-697-28654-1&rft_id=http%3A%2F%2Fwww.amazon.com%2FVertebrates-Comparative-Anatomy-Function-Evolution%2Fdp%2F0072909560">
- Vertebrata (TSN 331030). Integrated Taxonomic Information System. Accessed on 06 August 2007.
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