PYCNODONTIFORMES

order of extinct fishes of the class Actinopterygii, containing the genus Pycnodus, common in the Jurassic seas of 208 to 144 million years ago. Pycnodus is typical of pycnodonts, which were characterized by deep, narrow bodies that were very circular in outline in side view. The pycnodonts had a downturned beak and small mouth with an abundance of teeth. It is probable that they were adapted to feeding on coralline animals in the warm Jurassic seas.