Also See:
Class Actinopterigii Fish Fossils

Class Actinopterygii comprise the ray-finned fish, the dominant group of vertebrates, containing more than 27,000 extant species in fresh and salt water environments. The taxonomy below goes to the level of order. Interestingly, the Perciformes (meaning perch-like), at the table bottom, encompass about 40% of all fish and are the largest order of vertebrates with some 7000 species, with varying shapes and sizes, found in almost all aquatic environments. Perciformes first appeared and diversified in the Late Cretaceous.