Teleostomi

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Teleostomi
Temporal range: Latest Ordovician - Recent
Bluefin-big.jpg
The Atlantic bluefin tuna
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
(unranked): Teleostomi
C. L. Bonaparte, 1836
Classes and Clades

Acanthodii
Osteichthyes

Tetrapoda

Teleostomi is a clade of jawed vertebrates that includes the tetrapods, bony fish, and the wholly extinct acanthodian fish. Key characters of this group include an 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 chondrichthyans and the extinct class placodermi.

The clade Teleostomi should not be confused with the similar-sounding fish clade Teleostei.

Origins[edit]

The origins of the teleostomes are obscure, but their first known fossils are Acanthodians ("spiny sharks") from the Late Ordovician Period. 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[edit]

Teleostomes have two major adaptations that relate to aquatic respiration. First, the early teleostomes probably had some type of 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]

Acanthodians share with Actinopterygii the characteristic of three otoliths, 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.[1]

Taxonomy[edit]

Phylogeny[edit]

  Vertebrata  
  Gnathostomata  

  Placodermi  


  Eugnathostomata  

  Chondrichthyes  


  Teleostomi  

  Acanthodii  


  Osteichthyes  

  Actinopterygii  


  Tetrapodomorpha  
  Tetrapoda  

  Amphibia  


  Amniota  
  Sauropsida  

  Aves  




  Mammalia  










See also[edit]

References[edit]

  1. ^ Nelson, Joseph, S. (2006). Fishes of the World. John Wiley & Sons, Inc. ISBN 0-471-25031-7.