Neopterygii

Neopterygii is a group of fish. 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, because they can move more rapidly than their ancestors. Their scales and skeletons began to lighten during their evolution, and their jaws became more powerful and efficient.
The following diagram explains their relationship to the teleosts. Almost all modern fish are teleosts.