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Euteleostomi is a successful clade that includes more than 90% of the living species of vertebrates. Euteleostomes are also known as "bony vertebrates". Both major subgroups are successful today: Actinopterygii includes the majority of extant fish species, and Sarcopterygii includes the tetrapods. Euteleostomi is synonymous with "Osteichthyes" as the term is used in paleontology (i.e., "bony vertebrates"). In ichthyology and Linnaean taxonomy Osteichthyes, literally "bony fish," refers to the paraphyletic group that excludes tetrapods. The name Euteleostomi, coined as a (monophyletic) alternative that unambiguously includes the living tetrapods, is more widely used in bioinformatics and related fields. The term Euteleostomi comes from ''Eu-teleostomi'', where "Eu-" comes from the Greek εὖ meaning ''well'' or ''good'', so the clade can be defined as the living teleostomes. Euteleostomes originally all had endochondral bone, fins with lepidotrichs (fin rays), jaws lined by maxillary, premaxillary, and dentary bones composed of dermal bone, and lungs. Many of these characters have since been lost by descendant groups, however, such as lepidotrichs lost in tetrapods, and bone lost among the chondrostean fishes. Lungs have been retained in dipnoi (lungfish), and many tetrapods (birds, mammals, reptiles, and some amphibians). In many ray-finned fishes lungs have evolved into swim bladders for regulating buoyancy, while in others they continue to be used as respiratory gas bladders. ==Classification== Euteleostomi contains the following subgroups: Actinopterygii *Actinopteri * *Chondrostei * *Neopterygii *Cladistia * *Polypteriformes Sarcopterygii *Actinistia * *Coelacanthiformes *Dipnoi * *Ceratodontimorpha *Tetrapodomorpha 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Euteleostomi」の詳細全文を読む スポンサード リンク
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