Saurophaganax

***Saurophaganax*** ("lizard-eating master") is a genus of allosaurid theropod from the Morrison Formation, from Late Jurassic Oklahoma (late Kimmeridgian age, about 151 million years ago). Some paleontologists consider it to be a species of Allosaurus (*A. maximus*). *Saurophaganax* represents a very large Morrison allosaurid characterized by horizontal laminae at the bases of the dorsal neural spines above the transverse processes, and "meat-chopper" chevrons. Saurophaganax is the largest Jurassic theropod, with a length of 12 to 13 meters (1), making it larger than most known *Allosaurus and likely at the same size or possibly even larger than* *Tyrannosaurus rex*, making it one of the longest & largest terrestrial carnivore species of all time.

## Discovery and naming

In 1931 and 1932 John Willis Stovall uncovered remains of a large theropod near Kenton in Cimarron County, Oklahoma in layers of the late Kimmeridgian. In 1941 these were named *Saurophagus maximus* by Stovall in an article by journalist Grace Ernestine Ray. The generic name is derived from Greek *sauros*, "lizard" and *phagein*, "to eat", with the compound meaning of "eater of saurians". The specific epithet means "the largest" in Latin. As the naming article did not contain a description., the name remained a *nomen nudum*. In 1950 Stovall described the finds. However, in 1987 Spencer George Lucas e.a. concluded a lectotype had to be designated among the many bones: OMNH 4666, a tibia.

Later it was discovered that the name *Saurophagus* was preoccupied: it had already in 1831 been given by William Swainson to a tyrant-flycatcher, a real eater of lizards. In 1995 Daniel Chure named a new genus: *Saurophaganax*, adding Greek *anax*, "ruler", to the earlier name. Chure also established that the lectotype tibia was not diagnostic in relation to *Allosaurus*. He designated another element as the type specimen: OMNH 01123, a neural arch. This was not intended as a neotype of the old genus but as the holotype of a genus different from "Saurophagus". The type species *Saurophaganax maximus*, based on diagnostic material, is thus not to be considered conspecific with *Saurophagus maximus* based on a undiagnostic bone — which species Chure later stated to be a *nomen dubium* — and *Saurophaganax* is not a renaming of "Saurophagus". Much of the material previously referred to *Saurophagus maximus*, namely those diagnostic elements that could be distinguished from *Allosaurus*, were by Chure referred to *Saurophaganax maximus*. They contain disarticulated bones of at least four individuals. *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, NMMNH P-26083, a partial skeleton including a femur, several tail vertebrae, and a hip bone, has been found in northern New Mexico.

## Relationship with Allosaurus

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

## Ecology

*Saurophaganax* was one of the largest carnivore species of Late Jurassic North America and possibly the biggest land predator the world ever had until the end of late jurassic period. Ray even gave an estimate of the body length of fifteen metres and Chure of fourteen, though later estimations have been lower. 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 very large even for an allosaurid, and slightly bigger than its contemporaries Megalosaurus, Edmarka, Torvosaurus, and Allosaurus. Being much rarer than its contemporaries, making up one percent or less of the Morrison theropod fauna, not much about its behavior is known. Stovall in Oklahoma also unearthed a considerable number of Apatosaurus specimens, a possible prey for a large theropod.

## Diet

Saurophaganax was the largest known apex predator of the Morrison formation. It could have hunted and scavenged on anything available in it's area. Saurophaganax was able to hunt any dinosaur from Amphicoelias; in packs; to Camptosaurus. It's diet probably included large sauropods such as Amphicoelias, Sauroposeidon, Diplodocus, Apatosaurus, and the ornithopod Camptosaurus and sometimes even the heavily armored stegosaur, Stegosaurus which was mainly the prey item for it's close relative Allosaurus. Its unknown if it hunted alone or hunted in groups or packs when hunting large sauropods akin to other Allosaurid and Carcharodontosaurid species. Since there were so many predators in it's area like Allosaurus, Acrocanthosaurus, Siats, Edmarka, Torvosaurus, Ceratosaurus, and Megalosaurus it had a dangerous competition for food.