Editing Osteichthyes (section)

==Classification==
{{see also|Evolution of fish|List of prehistoric bony fish genera}}
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| quote = ...it is increasingly widely accepted that tetrapods, including ourselves, are simply modified bony fishes, and so we are comfortable with using the taxon Osteichthyes as a clade, which now includes all tetrapods...
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Traditionally, Osteichthyes was considered a [[Class (biology)|class]], recognised on the presence of a [[swim bladder]], only three pairs of [[gill arch]]es hidden behind a bony [[operculum (fish)|operculum]], and a predominantly bony skeleton.<ref name="Romer & Parson">{{cite book |last=Parsons |first=Thomas S. |author2=Romer, Alfred Sherwood |author2-link=Alfred Sherwood Romer |title=The vertebrate body|year=1986|publisher=Saunders College Pub.|location=Philadelphia|isbn=978-0-03-910754-3|edition=6th}}</ref> Under this classification system, Osteichthyes was considered [[paraphyletic]] with regard to [[tetrapoda|land vertebrates]], as the common ancestor of all osteichthyans includes [[tetrapod]]s amongst its descendants. While the largest subclass, Actinopterygii (ray-finned fish), is monophyletic, with the inclusion of the smaller subclass Sarcopterygii, Osteichthyes was regarded as paraphyletic.

This has led to the current [[Cladistics|cladistic]] classification which splits the Osteichthyes into several clades. Under this scheme Osteichthyes is monophyletic, as it includes the tetrapods making it a synonym of the clade [[Euteleostomi]]. Most bony fish belong to the ray-finned fish (Actinopterygii).

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! [[Actinopterygii]]
| [[File:Carassius carassius.jpg|140px]]{{center|<br />ray-finned fish}}
| valign=top | [[Actinopterygii]], members of which are known as '''ray-finned fishes''', is a [[Class (biology)|class]] of the bony fishes. The ray-finned fishes are so called because they possess [[lepidotrichia]] or "fin rays", their fins being webs of skin supported by bony or horny spines ("rays"), as opposed to the fleshy, lobed fins that characterize the clade [[Sarcopterygii]] which also possess lepidotrichia. These actinopterygian fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the link or connection between these fins and the internal skeleton (e.g., pelvic and pectoral girdles). In terms of numbers, actinopterygians are the dominant class of [[vertebrate]]s, comprising nearly 99% of the over 30,000 species of fish (Davis, Brian 2010). They are ubiquitous throughout [[freshwater]] and [[ocean|marine]] environments from the deep sea to the highest mountain streams. Extant species can range in size from ''[[Paedocypris]]'', at {{convert|8|mm|in|1|abbr=on}}, to the massive [[ocean sunfish]], at {{convert|2300|kg|lb|-1|abbr=on}}, and the long-bodied [[oarfish]], to at least {{convert|11|m|ft|0|abbr=on}}.
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! [[Sarcopterygii]]
| [[File:Coelacanth-bgiu.png|140px]]{{center|<br />lobe-finned fish and tetrapods}}
| [[Sarcopterygii]] ''(fleshy fin)'', members of which are known as '''lobe-finned fish''', is an unranked [[clade]] of the bony fishes. Traditionally, it is a [[class (biology)|class]] or subclass that excludes [[Tetrapoda]], a group of typically terrestrial vertebrates that descends from lobe-finned fish. However, under modern [[cladistic]] classification schemes, Sarcopterygii is a [[clade]] that includes the tetrapods. The living sarcopterygians are the [[coelacanth]]s, [[lungfish]], and tetrapods. Early lobe-finned fishes had fleshy, lobed, paired fins, joined to the body by a single bone.<ref>Clack, J. A. (2002) ''Gaining Ground''. Indiana University</ref> Their fins differ from those of all other fish in that each is borne on a fleshy, lobelike, scaly stalk extending from the body. Pectoral and pelvic fins have articulations resembling those of tetrapod limbs. These fins evolved into legs of the first tetrapod land vertebrates, [[amphibian]]s. They also possess two [[dorsal fin]]s with separate bases, as opposed to the single dorsal fin of [[Actinopterygii|actinopterygian]]s (ray-finned fish). The braincase of sarcoptergygians primitively has a hinge line, but this is lost in tetrapods and lungfish. Many early lobe-finned fishes have a symmetrical tail. All lobe-finned fishes possess teeth covered with true [[tooth enamel|enamel]].
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