| Saurophaganax | |
|---|---|
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| Holotype specimen, a dorsal neural arch | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | incertae sedis |
| Genus: | †Saurophaganax Chure, 1995 |
| Species: | †S. maximus |
| Binomial name | |
| †Saurophaganax maximus (Chure, 1995)[1] | |
| Synonyms | |
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Saurophaganax ("lord of lizard-eaters") is adubious,chimericgenus of largesaurischian dinosaur, possibly asauropod, from theLate Jurassic (Kimmeridgian)Morrison Formation ofOklahoma, United States. This taxon was historically considered to represent a species ofAllosaurus or very largeallosaurid. However, re-examinations of the attributed specimens suggested that it is a chimera of multiple dinosaur genera, since some specimens most likely belong to adiplodocidsauropod, while the other referred specimens could be reassigned to a novel species ofAllosaurus.
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In 1931 and 1932,John Willis Stovall uncovered remains of a large theropod nearKenton inCimarron County,Oklahoma in layers of the lateKimmeridgian. In 1941, these were namedSaurophagus maximus by Stovall in an article by journalistGrace Ernestine Ray.[2] The generic name is derived from Greekσαυρος,sauros, "lizard",φάγειν,phagein, "to eat", with the compound meaning of "lizard eater". Thespecific epithetmaximus means "the largest" inLatin. Because the naming article did not contain a description, the name remained anomen nudum. In 1987,Spencer George Lucas erroneously made OMNH 4666, atibia, thelectotype, unaware thatSaurophagus was anomen nudum.[3]
Later, it was discovered that the nameSaurophagus was preoccupied: in 1831, it had already been given byWilliam Swainson toa tyrant-flycatcher, an extant eater of taxonomically true lizards.[4] In 1995,Daniel Chure named a new genusSaurophaganax, adding Greek suffix -άναξ,anax which means "ruler", replacing the earlier informal name "Saurophagus"; he also found OMNH 4666 undiagnostic in relation toAllosaurus, so he chose OMNH 1123, aneural arch, as the holotype forSaurophaganax.[5][6] Much of the material informally named "Saurophagus maximus", namely those diagnostic elements that could be distinguished fromAllosaurus, were referred toSaurophaganax maximus by Chure; they contain disarticulated bones of at least four individuals.[5]
In 2024, Danison and colleagues revised the referral of various specimens assigned toSaurophaganax maximus including the fragmentary holotype neural arch (OMNH 1123) based on their comparative analysis. They suggested that the holotype could not confidently be regarded as a theropod or sauropod, although the complex accessory laminae are more comparable to those of sauropods, especially some juvenile specimens ofApatosaurus. Some referred specimens more likely belong to diplodocids than the large Kenton 1 Quarry allosaurid. Since the holotype neural arch is so fragmentary, the researchers could not confidently refer it to a theropod or sauropod, so they consideredSaurophaganax maximus to be anomen dubium.[7]
The identification of the allosaurid elements referred toSaurophaganax was a matter of dispute. It has been described as its own genus,[5] or as a species ofAllosaurus:Allosaurus maximus.[8] A review of basal tetanurans in 2004 and Carrano et al.'s comprehensive 2012 analysis of Tetanurae acceptedSaurophaganax as a distinct genus.[9][10] PossibleSaurophaganax material from New Mexico may clear up the status of the genus.[11] In 2019, Rauhut and colleagues noted that the definitive taxonomic placement ofSaurophaganax withinAllosauroidea is unstable, being recovered as a sister taxon ofMetriacanthosauridae or Allosauria, or even as a basalmost carcharodontosaurian.[12] Re-evaluation of the assigned specimens in a 2024 reassessment suggested that the referred allosaurid specimens belong to a novel species ofAllosaurus, named asAllosaurus anax.[7]
The Morrison Formation is a sequence of shallow marine and alluvial sediments which, according toradiometric dating, ranges between 156.3 million years old (Ma) at its base,[13] to 146.8 million years old at the top,[14] which places it in the lateOxfordian,Kimmeridgian, and earlyTithonianstages of the Late Jurassic period. This formation is interpreted as asemiarid environment with distinctwet anddry seasons. The Morrison Basin where dinosaurs lived, stretched from New Mexico to Alberta and Saskatchewan, and was formed when the precursors to theFront Range of the Rocky Mountains started pushing up to the west. The deposits from their east-facingdrainage basins were carried by streams andrivers and deposited inswampy lowlands, lakes, river channels andfloodplains.[15] This formation is similar in age to theSolnhofen Limestone Formation inGermany and theTendaguru Formation inTanzania. The fossils known ofSaurophaganax (both the possible material from New Mexico and the Oklahoma material) are known from the Brushy Basin Member, which is the latest part of the Morrison Formation, suggesting that this genus was either always uncommon or that it first appeared rather late in the Jurassic. Because of the rarity of discovered remains, not much about its behavior is known.[16]
The Morrison Formation records an environment and time dominated by gigantic sauropod dinosaurs such asBarosaurus,Apatosaurus,Brontosaurus,Camarasaurus,Diplodocus, andBrachiosaurus. Dinosaurs that lived alongsideSaurophaganax included the herbivorousornithischiansCamptosaurus,Dryosaurus,Stegosaurus, andNanosaurus. Predators in this paleoenvironment included thetheropodsTorvosaurus,Ceratosaurus,Marshosaurus,Stokesosaurus,Ornitholestes, and[17]Allosaurus, which accounted for 70 to 75% of theropod specimens and was at the toptrophic level of the Morrisonfood web.[18] Other vertebrates that shared this paleoenvironment includedray-finned fishes,frogs such asEobatrachus,salamanders,turtles,sphenodonts,lizards, terrestrial and aquaticcrocodylomorphs likeGoniopholis, and several species ofpterosaur likeKepodactylus. Early mammals were present in this region, such asFruitafossor,docodonts,multituberculates, symmetrodonts, andtriconodonts. The flora of the period has been revealed by fossils ofgreen algae,fungi,mosses,horsetails,cycads,ginkgoes, and several families ofconifers. Vegetation varied fromriver-lining forests oftree ferns, andferns (gallery forests), to fernsavannas with occasional trees such as theAraucaria-like coniferBrachyphyllum.[19]
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