Fossils Exihibition by Dalmasso Attilio

Vertebrates (/ˈvɜːrtəbrɪts, -ˌbreɪts/)^[3] comprise all animal taxa within the subphylum Vertebrata (/ˌvɜːrtəˈbreɪtə/)^[4] (chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with currently about 69,963 species described.^[5] Vertebrates comprise such groups as the following:

• jawless fish, which include hagfish and lampreys
• jawed vertebrates, which include:
  • cartilaginous fish (sharks, rays, and ratfish)
  • bony vertebrates, which include:
    • ray-fins (the majority of living bony fish)
    • lobe-fins, which include:
      • coelacanths and lungfish
      • tetrapods (limbed vertebrates)

Extant vertebrates range in size from the frog species Paedophryne amauensis, at as little as 7.7 mm (0.30 in), to the blue whale, at up to 33 m (108 ft). Vertebrates make up less than five percent of all described animal species; the rest are invertebrates, which lack vertebral columns.

The vertebrates traditionally include the hagfish, which do not have proper vertebrae due to their loss in evolution,^[6] though their closest living relatives, the lampreys, do.^[7] Hagfish do, however, possess a cranium. For this reason, the vertebrate subphylum is sometimes referred to as "Craniata" when discussing morphology. Molecular analysis since 1992 has suggested that hagfish are most closely related to lampreys,^[8] and so also are vertebrates in a monophyletic sense. Others consider them a sister group of vertebrates in the common taxon of craniata.^[9]