Euteleostomes

Euteleostomes are a clade that includes the most successful group of vertebrates ever to exist, consisting of more than 90% of extant species. They are also informally called "bony vertebrates". They divide in two groups, that respectivelly include the modern ray-finned bony fish and the tetrapods. Euteleostomi is, monophyletically, synonymous with Osteichthyes, the group that includes bony fish, but excludes tetrapods, so Osteichthyes is a form of paraphyletic classification. Euteleostomi englobes the tetrapods and the bony fish in one single monophyletic clade. The typical chracteristic of euteleostomes is their bony skeleton, which is however absent in chondrostean fish. The first euteleostomes had a form of lungs, that evolved into a swim bladder in ray-finned fishes, and maintained themselves in the group that includes tetrapods.