How are protacanthopterygian fishes related to modern teleost fishes?

The superorder Protacanthopterygii is classified as the most primitive group within the modern teleosts. As a diverse collection of relatively primitive orders—including Salmoniformes, Osmeriformes, and Esociformes—they represent an early stage in the evolutionary radiation of teleost fishes.12

These fishes are significant to the study of teleost evolution because they are considered to be closely related to the ancestors of more specialized groups. Specifically, several advanced superorders of modern teleosts, such as the Paracanthopterygii and Acanthopterygii, are believed to have arisen from early, protacanthopterygian-like ancestors. While modern teleosts as a whole are characterized by distinct functional advances—such as improved swimming ability, efficient feeding apparatuses, and the development of a true homocercal tail—the protacanthopterygians retain a more generalized morphology that provides insight into the evolutionary trends leading to the specialized forms seen in other modern bony fishes.23