Saurophaganax

*Saurophaganax maximus*

*Saurophaganax* (Greek meaning "lord of lizard eaters") 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 one of the largest known theropods of the entire Jurassic period, it weighed 4.5-6.8 tons, with a length of 10 to 12 meters, making it larger than Allosaurus and *Torvosaurus*.

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 in 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.

Though being officially classified as Allosaurid, Saurophaganax seems to have more carcharodontosaurid-like laminae on it's vertebra. This makes the position of this genus even more confusing than it already is. More research and analysis on Saurophaganax material is definitely required.

According to the Sam Noble Oklahoma Museum of Natural History vertebrate paleontology collection, there are over 200 undescribed elements of Saurophaganax.

## Disputed validity

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*. New possible Saurophaganax material from New Mexico may clear up the status of the genus. However, the most recently conducted research establishes Saurophaganax as a different taxon, due to distinctions in the anatomy of the vertebrae.

Saurophaganax was probably more robust than Allosaurus.

## History

John Willis Stovall in 1931 and 1932 discovered large theropod material near Kenton, Cimarron County, Oklahoma in Late Kimmeridgian-aged layers. In 1941, they were named Saurophagus maximus by Stovall in an article by Grace Ernestine Ray from the Greek σαυρος (sauros), "lizard" and φάγειν (phagein), "to eat", fully meaning of "lizard eater". Maximus means "the largest" in Latin. Since the article did not contain a description, it was a nomen nudum. Lucas assigned OMNH 4666, a fossil tibia, as the lectotype, and was unaware it was informally named.

However, in 1831, William Swainson had given the name to a tyrant-flycatcher. In 1995, Daniel Chure erected *Saurophaganax*. In relation, to *Allosaurus*, Chure found OMNH 4666 was undiagnostic, so he used OMNH 01123, a neural arch, as a holotype. Most of the elements referred to the nomen nudum can be differentiated from *Allosaurus*. At least four disarticulated individuals were attributed by Chure.

*Saurophaganax* is the state fossil of Oklahoma, with a large skeleton mounted in the Jurassic hall of the San Noble Oklahoma Museum of Natural History. NMMNH P-26083 is a partial skeleton (femur, tail vertebrae and a hip) and was found in New Mexico.

The name *Saurophaganax* is from the Greek "sauros", meaning reptile or lizard, "phagos," meaning eater, and "anax", meaning master, ruler or king. The meaning of the generic name according to Chure (1995) is "king of the reptile-eaters".

## Description

*Saurophaganax* is known from fragmentary remains. The holotype specimen consists of the fifth dorsal neural arch, though the paratypes consist of metatarsi, teeth, chevrons, a pubis, two quadrates, a humerus, tibia, a femur, an ischium, a partial ilium, and an ungual. Referred specimens include phalanges and additional femora, among other things.

*Saurophaganax* can be distinguished from other theropods by horizontal laminae, protruding from the bases of the dorsal neural spines, and unusual "meat-chopper" chevrons. While generally accepted as a distinct taxon, Saurophaganax is represented by at least four individuals, and it is difficult to refer fossils to specific ones.

## Classification

It is difficult to ascertain the classification of *Saurophaganax*. Some believe it to be a distinct taxon, while others believe it to be a species of *Allosaurus*, or even a large *A. fragilis*. It must be noted, though, that the authors of the 2020 paper describing *Allosaurus jimmadseni* chose to list *Saurophaganax* as its own genus. New material from New Mexico may clear up if *Saurophaganax* is distinct or not.

## Paleobiology

### 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*, Diplodocus and Apatosaurus. It's unknown if it hunted alone or hunted in groups or packs when hunting large sauropods akin to other allosaurid and Carcharodontosaurid species.

## Paleoenvironment

 File:Th - Skeleton of Saurophaganax.jpg
*Saurophaganax* was one of the largest carnivore species of Late Jurassic North America. Ray even gave an estimate of the body length of fifteen metres and Chure of fourteen, although this estimate is outdated, and newer estimates put it at 11.2-12.5 meters in length. 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. 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.

## Paleoecology

*Saurophaganax* was one of the largest Late Jurassic, North American predators. Chure estimated a length of 14 meters (46 feet), but other estimations are lower. All *Saurophaganax* are known ffrom the Brushy Basin Member, Morrison Formation, where it was likely uncommon or appeared late in the Jurassic. *Saurophaganax* was a large allosauroid, larger than contemporaneous genera *Torvosaurus tanneri* and *Allosaurus fragilis*, and was much rarer, making 1% or less of Morrison theropod fauna. Little behaviour is known.

The Morrison is a sequence of shallow marine and alluvial sediment, which is 156.3 million years old at the base and 146.8 million years old at the top, according to radiometric dating. This places the formation as Late Oxfordian, Kimmeridgian and Early Tithonian (Late Jurassic). It was semiarid, with wet and dry seasons. The Morrison Basin stretched from New Mexico to Saskatchewan, forming when the Front Range of the Rocky Mountains precursors pushed upwards and to the west. Deposits, from an eastward drainage, were carried by streams and rivers, depositing in swampy lowlands, lakes, river channels and floodplains. It is similar in age to the Solnhofen Formation and Tendaguru Formation. It was the center of the Bone Wars in 1877.

The fauna was dominated by sauropods, including: *Barosaurus*, *Apatosaurus*, *Brontosaurus*, *Camarasaurus*, *Diplodocus* and *Brachiosaurus*. Contemporaneous with *Saurophaganax*, and may have been prey, include *Camptosaurus*, *Dryosaurus*, *Stegosaurus* and *Nanosaurus*. Other predators include *Torvosaurus*, *Ceratosaurus*, *Marshosaurus*, *Stokesosaurus*, *Ornitholestes* and *Allosaurus*, who made 70-75% of theropods and the highest level in the trophic food web. Other vertebrates include ry-finned fish, frogs (like *Eobatrachus*), salamanders, turtles, sphenodonts, lizards, crocodylomorphs (like *Goniopholis*) and pterosaurs (like *Kepodactylus*). *Fruitafossor*, docodonts, multituberculates, symmetrodonts and triconodonts make up the mammal populations. Green algae, fungi, mosses, horsetails, cycads, ginkgoes and conifers make the flora. River-lining forests made of tree ferns, gallery forests, fern savannas with trees (*Brachyphyllum*) were all present environments. Stovall found *Apatosaurus* in Oklahoma, which could have been prey for *Saurophaganax*.

*Allosaurus* bites on *Mymoorapelta* were found (among other remains) in the Late Jurassic Mygatt-Moore Quarry. These left striations that, when measured to find the denticle width, produced a body size greater than any *Allosaurus* or *Ceratosaurus*, being the only like these found. It was either a large *Allosaurus*, or a separate taxon from *Torvosaurus* and *Saurophaganax* (which were not known from the quarry.. This increases the diversity of the site and produces great evidence for *Allosaurus* cannibalism. Based on the position and nutrient value of associated elements, the *Mymoorapelta* was predated or scavenged after death, with *Allosaurus* scavenging some time after death.

## JPInstitute.com Description

Saurophaganax may be a really big Allosaurus. This dinosaur would have been a huge meat-eater, possibly reaching 50 feet (15 m) long. Very little of its fossilized bones have been found so scientists are still deciding what to call this dinosaur. Some think it is a new type of Allosaurus and some think it should have its own name. More of the fossils need to be found in order to settle the debate.

## Links

http://web.archive.org/web/20040214160641fw\_/http://www.jpinstitute.com/dinopedia/dinocards/dc\_saurophaganax.html#