Ichthyodectiformes

Ichthyodectiformes is an extinct order of marine stem-teleost ray-finned fish. They were most diverse throughout the Cretaceous period. You can see their "bulldog" appearance, which is why they are also called sea bulldogs. Ichthyodectiforms are usually considered to be called like that because of their unique appearance. There is evidence that at least one species, "Xiphactinus audax", may have been endothermic ("warm-blooded").