Euteleostomi is a successful clade

Clade

A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

 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 tetrapod

Tetrapod

Tetrapods are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent. The earliest tetrapods evolved from the lobe-finned fishes in the Devonian...

s. This clade is sometimes called "Osteichthyes

Osteichthyes

Osteichthyes , also called bony fish, are a taxonomic group of fish that have bony, as opposed to cartilaginous, skeletons. The vast majority of fish are osteichthyes, which is an extremely diverse and abundant group consisting of over 29,000 species...

", but since that name literally means "bony fish" and traditionally is a paraphyletic group that excludes tetrapods, the name Euteleostomi was coined as a substitute.

Euteleostomes originally all had endochondral bone, fins with lepidotrichs, and jaws lined by maxillary, premaxillary, and dentary bones. Many of these characters have since been lost by descendant groups, however, such as lepidotrichs lost in tetrapod

Tetrapod

Tetrapods are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent. The earliest tetrapods evolved from the lobe-finned fishes in the Devonian...

s, and bone lost among the chondrostean

Chondrostei

Chondrostei are primarily cartilaginous fish showing some ossification. There are 52 species divided among two orders, the Acipenseriformes and the Polypteriformes ....

 fishes.

Classification

Euteleostomi contains the following subgroups:

Actinopterygii

Actinopterygii

The Actinopterygii or ray-finned fishes constitute a class or sub-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 , as opposed to the fleshy, lobed fins that characterize...

• Actinopteri
  Actinopteri
  Actinopteri is the sister group of Cladistia. Dating back to the Permian period, the Actinopteri are comprise the Chondrostei and the Neopterygii . Modern actinopterygians generally feed using a suction mechanism, with the mouth parts forming a tube. Prey are drawn in, and then masticated for...
  
  
  • Chondrostei
    Chondrostei
    Chondrostei are primarily cartilaginous fish showing some ossification. There are 52 species divided among two orders, the Acipenseriformes and the Polypteriformes ....
    
    
  • Neopterygii
    Neopterygii
    Neopterygii is a group of Actinopteri animals. Neopterygii means "new fins". There are only few changes during their evolution from the earlier actinopterygians. They appeared somewhere in the Late Permian, before the time of the dinosaurs. The Neopterygii is a very successful group of fishes,...
    
    
• Polypteriformes
  • Polypteridae

Sarcopterygii

Sarcopterygii

The Sarcopterygii or lobe-finned fishes – sometimes considered synonymous with Crossopterygii constitute a clade of the bony fishes, though a strict classification would include the terrestrial vertebrates...

• Coelacanthimorpha
  • Coelacanthiformes
• Dipnoi
  • Ceratodontimorpha
• Tetrapodomorpha
  Tetrapodomorpha
  Tetrapodomorpha is a clade of vertebrates, consisting of tetrapods and their closest sarcopterygian relatives that are more closely related to living tetrapods than to living lungfish...
  
  
  • Tetrapoda
    • Amniota
    • Amphibia