A monophyletic grade of craniates comprising Acanthodii, Actinopterygii (ray-finned fishes), and Sarcopterygii (coelacanths, lungfishes, and tetrapods). (Monophyletic refers to any form evolved from a single interbreeding population. Craniates are vertebrates distinguished by a cranium.) The Acanthodii (all fossil species) is the sister group to the actinopterygians and sarcopterygians, a relationship based on otoliths and certain details of the vertebral column and associated elements. The term Teleostomi, coined by C. L. Bonaparte in 1836, has changed in meaning, as have Acanthodii and Actinopterygii, which originated with E. D. Cope in 1871. The term Osteichthyes, first used by T. H. Huxley in 1880, is not used by J. S. Nelson in a formal taxonomic sense; however, the term is conveniently used for the vast number of fishes with a bony skeleton. The term Sarcopterygii was used by A. S. Romer to include the lobed-finned fishes, that is, crossopterygians and dipnoans; however, E. O. Wiley, and D. E. Rosen and collaborators include the tetrapods in Sarcopterygii to form a monophyletic group. The grade Teleostomi contains about 53,633 extant valid species, of which 26,891 are actinopterygians and 26,742 are sarcopterygians.