Neopterygii


Neopterygii are a subclass of ray-finned fish. Only a few changes occurred during their evolution from the earlier actinopterygians. They appeared sometime in the Late Permian, before the time of the dinosaurs. The Neopterygii were a very successful group of fish, because they could move more rapidly than their ancestors. Their scales and skeletons began to lighten during their evolution, and their jaws became more powerful and efficient. While electroreception and the ampullae of Lorenzini are present in all other groups of fish, with the exception of hagfish, Neopterygii have lost this sense, even if it has later been re-evolved within Gymnotiformes and catfishes, which possess nonhomologous teleost ampullae.
A very important step in the evolution of the actinopterygian fishes is the origin of the Neopterygii, with the acquisition of a better control of the movements of both dorsal and anal fins, resulting in an improvement in their swimming capabilities. They additionally acquired several modifications in the skull, which allowed the evolution of different feeding mechanisms and consequently the colonization of new ecological niches. All of these characters represented major improvements, so that the Neopterygii became the dominant group of fishes, and they also include the vast majority of the modern fishes, the teleosts.

Classification