Halecostomi
Halecostomi is the name of a group of neopterygian fish uniting the halecomorphs and the teleosts, the largest group of extant ray-finned fish.
The Halecostomi hypothesis and the Holostei hypothesis are two competing hypotheses explaining the evolutionary relationships of living ray-finned fish. The Holostei hypothesis is better supported, rendering the Halecostomi a paraphyletic group.
The Holostei hypothesis posits that Ginglymodi and Halecomorphi form a clade, called Holostei, and that the Holostei are the sister group to the Teleostei.