View source for Teleostomi

{{Short description|Clade of jawed vertebrates}}{{Distinguish|Teleost}}{{Automatic taxobox
| name = Teleostomes
| fossil_range = {{fossil range|445|0}}[[Ordovician]] – [[Holocene|Present]]
| image = Acanthodes BW.jpg
| image_upright = 1.25
| image_caption = an [[acanthodian]]<!-- (''[[Acanthodes bronni]]'') -->
| image2 = Osteichthyes.jpg
| image2_caption = Four species of [[bony fish]]<!-- [[Queensland lungfish]] (top-left), [[iridescent shark]] (top-right), [[West Indian Ocean coelacanth]] (bottom-left) and [[Acipenser oxyrinchus|American black sturgeon]] (bottom-right) -->
| classification_status = obsolete as paraphyletic
| taxon = Teleostomi
| authority = [[Charles Lucien Bonaparte|C. L. Bonaparte]], 1836
| subdivision_ranks = Subgroups
| subdivision = * {{extinct}}[[Acanthodii]]
* [[Euteleostomi]] ("[[Osteichthyes]]")
** [[Actinopterygii]] (majority of all fish)
** [[Sarcopterygii]] (includes [[tetrapods]])
}}
{{more citations needed|talk=Obsolete/invalid?|date=May 2025}}
'''Teleostomi''' (from [[Greek language|Greek]] τελεος, complete + Greek στόμα, mouth) is an [[List of obsolete taxa|obsolete taxon]]<ref name="pmid24067611" /> of [[Gnathostomata|jawed vertebrates]] that supposedly includes the [[tetrapod]]s, [[osteichthyes|bony fish]], and the wholly extinct [[Acanthodii|acanthodian]] fish. Key characters of this group include an [[operculum (fish)|operculum]] and a single pair of respiratory openings, features which were lost or modified in some later representatives. The teleostomes include all jawed vertebrates except the [[chondrichthyes|chondrichthyans]] and the [[Extinction (biology)|extinct]] [[Class (biology)|class]] [[Placodermi]].

Recent studies indicate that [[Osteichthyes]] evolved from [[placoderms]] like ''[[Entelognathus]]'', while acanthodians are more closely related to modern chondrichthyes. Teleostomi, therefore, is not a valid, natural clade, but a [[paraphyletic]] group of  species.<ref name="pmid24067611">{{cite journal | vauthors = Zhu M, Yu X, Ahlberg PE, Choo B, Lu J, Qiao T, Qu Q, Zhao W, Jia L, Blom H, Zhu Y | title = A Silurian placoderm with osteichthyan-like marginal jaw bones | journal = Nature | volume = 502 | issue = 7470 | pages = 188–93 | date = October 2013 | pmid = 24067611 | doi = 10.1038/nature12617 | bibcode = 2013Natur.502..188Z | s2cid = 4462506 }}</ref>

== Origins ==
The origins of the teleostomes are obscure. They are traditionally assumed to be descendants of the [[acanthodian]]s ("spiny sharks") from the [[Llandovery epoch|Early Silurian]] Period; however, more recent discoveries show that the "spiny sharks" are actually a paraphyletic assemblage leading to [[Chondrichthyes]], and that placoderms like ''[[Entelognathus]]'' are more closely related to true bony fish.<ref name="pmid24067611"/>  Living teleostomes constitute the clade [[Euteleostomi]], which includes all osteichthyans and tetrapods.  Even after the acanthodians perished at the end of the [[Permian]], their euteleostome relatives flourished such that today they comprise 99% of living vertebrate species.

== Physical characteristics ==
Teleostomes have two major adaptations that relate to [[aquatic respiration]]. First, the early teleostomes probably had some type of [[operculum (fish)|operculum]]; however, it was not the one-piece affair of living [[fish]]. The development of a single respiratory opening seems to have been an important step. The second adaptation, the teleostomes also developed a primitive lung with the ability to use some atmospheric [[oxygen]].  This developed, in later species, into the lung and (later) the swim bladder, used to keep the fish at neutral buoyancy.{{Citation needed|date=June 2007}}

Acanthodians share with [[actinopterygians]] the characteristic of three [[otolith]]s, the sagitta in the sacculus, the asteriscus in the lagena, and the lapillus in the utriculus. In dipnoans there are only two otoliths and in ''Latimeria'' there is only one.<ref name="Nelson">{{cite book | title = Fishes of the World | last = Nelson | first = Joseph, S. | publisher = John Wiley & Sons, Inc. | year = 2006 | isbn = 0-471-25031-7}}</ref>

However, most of the above synapomorphies can ultimately be found in several chondrichthyan groups.<ref name = ozarcus>{{cite journal | vauthors = Pradel A, Maisey JG, Tafforeau P, Mapes RH, Mallatt J | title = A Palaeozoic shark with osteichthyan-like branchial arches | journal = Nature | volume = 509 | issue = 7502 | pages = 608–11 | date = May 2014 | pmid = 24739974 | doi = 10.1038/nature13195 | bibcode = 2014Natur.509..608P | s2cid = 3504437 }}</ref>

== Relationships ==
{{Barlabel |size=5 |at=4 |label='''Teleostomi''' |bar=green
|cladogram={{clade
  |label1=[[Gnathostomata]]
  |1={{clade |state1=double
    |1=&thinsp;†[[Placodermi]] ([[paraphyletic]])
    |label2=[[Eugnathostomata]]
    |2={{clade
      |label1=[[Chondrichthyes]]&ensp; |sublabel1=([[total group]])
      |1={{clade |state2=double
        |1=&thinsp;[[Chondrichthyes]] ([[crown group]])
        |2=&thinsp;†[[Acanthodii]] ([[paraphyletic]]) |barbegin2=green
         }}
      |label2=[[Osteichthyes]]
      |2={{clade
        |1=&thinsp;[[Actinopterygii]] |bar1=green
        |2=&thinsp;[[Sarcopterygii]] (includes [[tetrapod]]s)&ensp; |barend2=green
}} }} }} }} }}

== References ==
{{Reflist}}

{{Taxonbar|from=Q134681}}
{{Portal bar|Fish}}

[[Category:Gnathostomata]]
[[Category:Late Ordovician first appearances]]
[[Category:Extant Ordovician first appearances]]
[[Category:Taxa named by Charles Lucien Bonaparte]]
[[Category:Taxa described in 1836]]
[[Category:Paraphyletic groups]]
[[Category:Obsolete vertebrate taxa]]