Pachycormiformes
Pachycormiformes is an extinct order of marine ray-finned fish. They lived in the  the early Jurassic period to the end of the Cretaceous. It only includes a single family, the Pachycormidae. They were characterized by having serrated pectoral fins (though more recent studies demonstrated that fin shape diversity in this group was high), reduced pelvic fins and a bony rostrum.