Osteichthyes

Osteichthyes Temporal range: Late Silurian–Present, 425–0 Ma[1] PreꞒ Ꞓ O S D C P T J K Pg N
Example of Osteichthyes: Queensland lungfish and West Indian Ocean coelacanth (two Sarcopterygii), iridescent shark and American black sturgeon (two Actinopterygii)
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Subphylum:	Vertebrata
Infraphylum:	Gnathostomata
Clade:	Eugnathostomata
Clade:	Teleostomi
Superclass:	Osteichthyes Huxley, 1880
Classes
†Ligulalepis †Dialipina †Andreolepis †Lophosteus ?†"Psarolepids" Guiyu Sparalepis Psarolepis Achoania Actinopterygii (ray-finned fish) Sarcopterygii (lobe-finned fish, including tetrapods)

Osteichthyes (/ˌɒstiːˈɪkθiːz/ ost-ee-IK-theez),^[2] also known as osteichthyans or commonly referred to as the bony fish, is a diverse superclass of vertebrate animals that have endoskeletons primarily composed of bone tissue. They can be contrasted with the Chondrichthyes (cartilaginous fish) and the extinct placoderms and acanthodians, which have endoskeletons primarily composed of cartilage. The vast majority of extant fish are members of Osteichthyes, being an extremely diverse and abundant group consisting of 45 orders, over 435 families and 28,000 species.^[3] It is the largest class of vertebrates in existence today, encompassing most aquatic vertebrates, as well as all semi-aquatic and terrestrial vertebrates.

The group is divided into two main clades, the ray-finned fish (Actinopterygii, which makes up the vast majority of extant fish) and the lobe-finned fish (Sarcopterygii, which gave rise to all land vertebrates, i.e. tetrapods). The oldest known fossils of bony fish are about 425 million years old from the late Silurian,^[1] which are also transitional fossils showing a tooth pattern that is in between the tooth rows of sharks and true bony fishes.^[4] Despite the name, these early basal bony fish had not yet evolved ossification and their skeletons were still mostly cartilaginous, and the main distinguishing feature that set them apart from other fish clades were the development of foregut pouches that eventually evolved into the swim bladders and lungs, respectively.

Osteichthyes can be compared to Euteleostomi. In paleontology the terms are synonymous. In ichthyology the difference is that Euteleostomi presents a cladistic view which includes the terrestrial tetrapods that evolved from lobe-finned fish. Until recently, the view of most ichthyologists has been that Osteichthyes were paraphyletic and include only fishes.^[5] However, since 2013 widely cited ichthyology papers have been published with phylogenetic trees that treat the Osteichthyes as a clade including tetrapods.^[6][7][8][5]