From Wikipedia, the free encyclopedia

This article does not cite any references or sources. (May 2007) Please help improve this article by adding citations to reliable sources. Unverifiable material may be challenged and removed.

Vertebrates Fossil range: mid Early Cambrian to Recent
Northern bluefin tuna, Thunnus thynnus
Scientific classification
Kingdom: Animalia Phylum: Chordata (unranked) Craniata Subphylum: Vertebrata Cuvier, 1812
Classes and Clades
See below

Vertebrates are members of the subphylum Vertebrata (within the phylum Chordata), specifically, those chordates with backbones or spinal columns. About 57,739 species of vertebrates have been described^{[citation needed]}. Vertebrata is the largest subphylum of chordates, and contains many familiar groups of large land animals. Fish (including lampreys, but traditionally not hagfish, though this is now disputed), amphibians, reptiles, birds, and mammals (including humans) are vertebrates.

Characteristics 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.^{[citation needed]}

This short section requires expansion.

This short section requires expansion.

Vertebrates started to evolve about 530 million years ago during the Cambrian explosion, which is part of the Cambrian period (first known vertebrate is Myllokunmingia).^{[citation needed]} 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.^{[citation needed]}

Classification after Janvier (1981, 1997), Shu et al. (2003), and Benton (2004).^[1]

• 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 Coelacanthimorpha (coelacanths)
• 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)

Their name derives from the bones of the spinal column (or vertebral column), the vertebrae.^{[citation needed]}

• Invertebrate

• Tree of Life
• Tunicates and not cephalochordates are the closest living relatives of vertebrates

Wikispecies has information related to:

Vertebrata

The subject of this article has been identified by the Missing Encyclopedic Articles project as being a high priority for expansion.