Chondrosteidae is a family of extinct marine actinopterygian fishes, known from the Early Jurassic of Europe. They are closely related to modern sturgeons and paddlefish of the order Acipenseriformes, and are either placed as part of that order or the separate order Chondrosteiformes within the Chondrostei. Three genera are known, Chondrosteus, Gyrosteus, and Strongylosteus. Included species were of large size, with body lengths ranging from 2 m up to 7 m. Their skeleton was largely made up of bones (unlike living chondrosteans), but ossification was reduced compared to other ray-fins.