Which fossil fish group gave rise to later chondrosteans and holosteans?

The fossil fish group that served as the basal stock from which all other chondrosteans and holosteans evolved is the order Palaeonisciformes.12

These ancient ray-finned fishes first appeared in the fossil record at the end of the Silurian Period and were the most common fishes of their time. While the order itself is considered a series of families with poorly understood interrelationships rather than a single natural group, they provided the evolutionary foundation for more advanced actinopterygians. During the Permian and Triassic periods, advanced palaeoniscids—sometimes referred to as subholosteans—emerged, bridging the gap toward the holostean level of anatomical organization.12