Perleidus

Perleidus is an extinct genus of ray-finned fish from the Triassic period. Fossils have been found worldwide.

Description
Perleidus was a freshwater predatory fish, about 15 centimetres (5.9 in) in length. Its jaws hung vertically under the braincase, allowing them to open wide, a feature it shared with the earlier palaeonisciform fish, from which it may have been descended. Unlike those earlier fish, however, Perleidus and its relatives had highly flexible dorsal and anal fins, with a reduced number of fin rays. This would have made the fish more agile in the water.