Saurophaganax

Saurophaganax ("lizard-eating master") is a genus of allosaurid dinosaur from the Morrison Formation of Jurassic North America. Some paleontologists consider it to be a species of Allosaurus (A. maximus). Saurophaganax represents a very large (10.9 meters (36 ft) long) Morrison allosaurid characterized by horizontal laminae at the bases of the dorsal neural spines above the transverse processes, and "meat-chopper" chevrons.

Much material previously referred to Saurophagus maximus is actually referable to Saurophaganax maximus. The new genus is needed because the original type specimen of Saurophagus maximus is not diagnostic, whereas the material described by Dan Chure is. Note that the type species Saurophaganax maximus is not to be considered conspecific with Saurophagus maximus (which is a nomen dubium), so Saurophaganax is not a renaming of Saurophagus.

Saurophaganax is the official state fossil of Oklahoma, and a large skeleton of Saurophaganax can be seen in the Jurassic hall in the Sam Noble Oklahoma Museum of Natural History. Although the best known Saurophaganax material was found in the panhandle of Oklahoma, possible Saurophaganax material, including a femur, several tail vertebrae, and a hip bone, have been found in northern New Mexico.

Ecology
Saurophaganax was the largest carnivore of Late Jurassic North America. The fossils known of Saurophaganax (both the possible New Mexican material and the Oklahoma material) are known from the latest part of the Morrison formation, suggesting that they were either always uncommon or appeared rather late in the fossil record. Saurophaganax was large for an allosaurid, and bigger than both its contemporaries Torvosaurus tanneri and Allosaurus fragilis. Being much rarer than its contemporaries, making up one percent or less of the Morrison theropod fauna, not much about its behavior is known.

Allosaurus vs. Saurophaganax
The identification of Saurophaganax is a matter of dispute. It has been described as its own genus, or as a species of Allosaurus (A. maximus). The most recent review of basal tetanurans accepted Saurophaganx as a distinct genus. New possible Saurophaganax material from New Mexico may clear up the status of Saurophaganax.