Saurophaganax

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Saurophaganax
Temporal range: Late Jurassic
Kimmeridgian
Saurophaganax maximus (holotype, OMNH 112).png
Holotype specimen, a dorsal neural arch
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: incertae sedis
Genus:† Saurophaganax
Chure, 1995
Species:
†S. maximus
Binomial name
†Saurophaganax maximus
Chure, 1995
Synonyms

Saurophaganax ("lord of lizard-eaters") is a dubious, chimeric genus of large saurischian dinosaur, possibly a sauropod, from the Late Jurassic (Kimmeridgian) Morrison Formation of Oklahoma, United States. This taxon was historically considered to represent a species of Allosaurus or very large allosaurid. However, re-examinations of the attributed specimens suggested that it is a chimera of multiple dinosaur genera, since some specimens most likely belong to a diplodocid sauropod, while the other referred specimens could be reassigned to a novel species of Allosaurus.

Contents

Discovery and naming

A drawer of vertebrae historically assigned to Saurophaganax, Oklahoma Museum of Natural History Saurophaganax (2).jpg
A drawer of vertebrae historically assigned to Saurophaganax, Oklahoma Museum of Natural History

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. [1] The generic name is derived from Greek σαυρος, sauros, "lizard", φάγειν, phagein, "to eat", with the compound meaning of "lizard eater". The specific epithet maximus means "the largest" in Latin. Because the naming article did not contain a description, the name remained a nomen nudum . In 1987, Spencer George Lucas erroneously made OMNH 4666, a tibia, the lectotype, unaware that Saurophagus was a nomen nudum. [2]

Later, it was discovered that the name Saurophagus was preoccupied: in 1831, it had already been given by William Swainson to a tyrant-flycatcher, an extant eater of taxonomically true lizards. [3] In 1995, Daniel Chure named a new genus Saurophaganax, adding Greek suffix -άναξ, anax which means "ruler", replacing the earlier informal name "Saurophagus"; he also found OMNH 4666 undiagnostic in relation to Allosaurus, so he chose OMNH 1123, a neural arch, as the holotype for Saurophaganax. [4] [5] Much of the material informally named "Saurophagus maximus", namely those diagnostic elements that could be distinguished from Allosaurus, were referred to Saurophaganax maximus by Chure; they contain disarticulated bones of at least four individuals. [4]

In 2024, Danison and colleagues revised the referral of various specimens assigned to Saurophaganax 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 of Apatosaurus. 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 couldn't confidently refer it to a theropod or sauropod, so they considered Saurophaganax maximus to be a nomen dubium . [6]

Previously assigned allosaurid specimens

Mounted skeletons showing Saurophaganax as an Allosaurus-like taxon attacking Apatosaurus sp., in Oklahoma Museum of Natural History. The latter dinosaur may be closer to the actual identity of Saurophaganax Clash of Titans Saurophaganax and Apatosaurus.jpg
Mounted skeletons showing Saurophaganax as an Allosaurus -like taxon attacking Apatosaurus sp., in Oklahoma Museum of Natural History. The latter dinosaur may be closer to the actual identity of Saurophaganax

The identification of the allosaurid elements referred to Saurophaganax was a matter of dispute. It has been described as its own genus, [4] or as a species of Allosaurus: Allosaurus maximus. [7] A review of basal tetanurans in 2004 and Carrano et al.'s comprehensive 2012 analysis of Tetanurae accepted Saurophaganax as a distinct genus. [8] [9] Possible Saurophaganax material from New Mexico may clear up the status of the genus. [10] In 2019, Rauhut and colleagues noted that the definitive taxonomic placement of Saurophaganax within Allosauroidea is unstable, being recovered as a sister taxon of Metriacanthosauridae or Allosauria, or even as a basalmost carcharodontosaurian. [11] Re-evaluation of the assigned specimens in a 2024 reassessment suggested that the referred allosaurid specimens belong to a novel species of Allosaurus , named as Allosaurus anax. [6]

Paleoenvironment

The Morrison Formation is a sequence of shallow marine and alluvial sediments which, according to radiometric dating, ranges between 156.3 million years old (Ma) at its base, [12] to 146.8 million years old at the top, [13] which places it in the late Oxfordian, Kimmeridgian, and early Tithonian stages of the Late Jurassic period. This formation is interpreted as a semiarid environment with distinct wet and dry seasons. The Morrison Basin where dinosaurs lived, stretched from New Mexico to Alberta and Saskatchewan, and was formed when the precursors to the Front Range of the Rocky Mountains started pushing up to the west. The deposits from their east-facing drainage basins were carried by streams and rivers and deposited in swampy lowlands, lakes, river channels and floodplains. [14] This formation is similar in age to the Solnhofen Limestone Formation in Germany and the Tendaguru Formation in Tanzania. The fossils known of Saurophaganax (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. [15]

The Morrison Formation records an environment and time dominated by gigantic sauropod dinosaurs such as Barosaurus , Apatosaurus , Brontosaurus , Camarasaurus , Diplodocus , and Brachiosaurus . Dinosaurs that lived alongside Saurophaganax included the herbivorous ornithischians Camptosaurus , Dryosaurus , Stegosaurus , and Nanosaurus . Predators in this paleoenvironment included the theropods Torvosaurus , Ceratosaurus , Marshosaurus , Stokesosaurus , Ornitholestes , and [16] Allosaurus , which accounted for 70 to 75% of theropod specimens and was at the top trophic level of the Morrison food web. [17] Other vertebrates that shared this paleoenvironment included ray-finned fishes, frogs such as Eobatrachus , salamanders, turtles, sphenodonts, lizards, terrestrial and aquatic crocodylomorphs like Goniopholis , and several species of pterosaur like Kepodactylus . Early mammals were present in this region, such as Fruitafossor , docodonts, multituberculates, symmetrodonts, and triconodonts. The flora of the period has been revealed by fossils of green algae, fungi, mosses, horsetails, cycads, ginkgoes, and several families of conifers. Vegetation varied from river-lining forests of tree ferns, and ferns (gallery forests), to fern savannas with occasional trees such as the Araucaria -like conifer Brachyphyllum . [18]

Related Research Articles

<i>Apatosaurus</i> Sauropod dinosaur genus from Late Jurassic period

Apatosaurus is a genus of herbivorous sauropod dinosaur that lived in North America during the Late Jurassic period. Othniel Charles Marsh described and named the first-known species, A. ajax, in 1877, and a second species, A. louisae, was discovered and named by William H. Holland in 1916. Apatosaurus lived about 152 to 151 million years ago (mya), during the late Kimmeridgian to early Tithonian age, and are now known from fossils in the Morrison Formation of modern-day Colorado, Oklahoma, New Mexico, Wyoming, and Utah in the United States. Apatosaurus had an average length of 21–23 m (69–75 ft), and an average mass of 16.4–22.4 t. A few specimens indicate a maximum length of 11–30% greater than average and a mass of approximately 33 t.

<i>Allosaurus</i> Extinct genus of carnosaurian theropod dinosaur

Allosaurus is an extinct genus of large carnosaurian theropod dinosaur that lived 155 to 145 million years ago during the Late Jurassic period. The name "Allosaurus" means "different lizard", alluding to its unique concave vertebrae. It is derived from the Greek words ἄλλος and σαῦρος. The first fossil remains that could definitively be ascribed to this genus were described in 1877 by famed paleontologist Othniel Charles Marsh. The genus has a very complicated taxonomy and includes at least three valid species, the best known of which is A. fragilis. The bulk of Allosaurus remains have come from North America's Morrison Formation, with material also known from the Alcobaça Formation and Lourinhã Formation in Portugal with teeth known from Germany. It was known for over half of the 20th century as Antrodemus, but a study of the abundant remains from the Cleveland-Lloyd Dinosaur Quarry returned the name "Allosaurus" to prominence. As one of the first well-known theropod dinosaurs, it has long attracted attention outside of paleontological circles.

<i>Camarasaurus</i> Camarasaurid sauropod dinosaur genus from Late Jurassic Period

Camarasaurus was a genus of quadrupedal, herbivorous dinosaurs and is the most common North American sauropod fossil. Its fossil remains have been found in the Morrison Formation, dating to the Late Jurassic epoch, between 155 and 145 million years ago.

<i>Ceratosaurus</i> Genus of theropod dinosaur from the Late Jurassic period

Ceratosaurus was a carnivorous theropod dinosaur that lived in the Late Jurassic period. The genus was first described in 1884 by American paleontologist Othniel Charles Marsh based on a nearly complete skeleton discovered in Garden Park, Colorado, in rocks belonging to the Morrison Formation. The type species is Ceratosaurus nasicornis.

<i>Torvosaurus</i> Megalosaurid theropod dinosaur genus from Late Jurassic Period

Torvosaurus is a genus of large megalosaurine theropod dinosaur that lived approximately 165 to 148 million years ago during the Callovian to Tithonian ages of the late Middle and Late Jurassic period in what is now Colorado, Portugal, Germany, and possibly England, Spain, Tanzania, and Uruguay. It contains two currently recognized species, Torvosaurus tanneri and Torvosaurus gurneyi, plus a third unnamed species from Germany.

<i>Barosaurus</i> Diplodocid sauropod dinosaur genus from Upper Jurassic Period

Barosaurus was a giant, long-tailed, long-necked, plant-eating sauropod dinosaur closely related to the more familiar Diplodocus. Remains have been found in the Morrison Formation from the Upper Jurassic Period of Colorado, Utah, South Dakota, and eastern Wyoming at Como Bluff. It is present in stratigraphic zones 2–5.

<i>Dryosaurus</i> Extinct genus of dinosaurs

Dryosaurus is a genus of an ornithopod dinosaur that lived in the Late Jurassic period. It was an iguanodont. Fossils have been found in the western United States and were first discovered in the late 19th century. Valdosaurus canaliculatus and Dysalotosaurus lettowvorbecki were both formerly considered to represent species of Dryosaurus.

Coelurus is a genus of coelurosaurian dinosaur from the Late Jurassic period. The name means "hollow tail", referring to its hollow tail vertebrae. Although its name is linked to one of the main divisions of theropods (Coelurosauria), it has historically been poorly understood, and sometimes confused with its better-known contemporary Ornitholestes. Like many dinosaurs studied in the early years of paleontology, it has had a confusing taxonomic history, with several species being named and later transferred to other genera or abandoned. Only one species is currently recognized as valid: the type species, C. fragilis, described by Othniel Charles Marsh in 1879. It is known from one partial skeleton found in the Morrison Formation of Wyoming, United States. It was a small bipedal carnivore with elongate legs.

<span class="mw-page-title-main">Allosauridae</span> Extinct family of theropod dinosaurs

Allosauridae is an extinct family of medium to large bipedal, carnivorous allosauroid theropod dinosaurs from the Late Jurassic. Allosauridae is a fairly old taxonomic group, having been first named by the American paleontologist Othniel Charles Marsh in 1878.

<i>Stokesosaurus</i> Extinct genus of dinosaurs

Stokesosaurus is a genus of small, carnivorous early tyrannosauroid theropod dinosaurs from the late Jurassic period of Utah, United States and Guimarota, Portugal.

<i>Epanterias</i> Extinct genus of dinosaurs

Epanterias is a dubious genus of theropod dinosaur from the Tithonian age Upper Jurassic upper Morrison Formation of Garden Park, Colorado. It was described by Edward Drinker Cope in 1878. The type species is Epanterias amplexus. This genus is based on what is now AMNH 5767, parts of three vertebrae, a coracoid, and a metatarsal. Although Cope thought it was a sauropod, it was later shown to be a theropod. Gregory S. Paul reassessed the material as pertaining to a large species of Allosaurus in 1988. Other authors have gone further and considered E. amplexus as simply a large individual of Allosaurus fragilis. In 2010, Gregory S. Paul and Kenneth Carpenter noted that the E. amplexus specimen comes from higher in the Morrison Formation than the type specimen of Allosaurus fragilis, and is therefore "probably a different taxon". They also considered its holotype specimen not diagnostic and classified it as a nomen dubium.

<i>Szechuanosaurus</i> Extinct genus of dinosaurs

Szechuanosaurus is an extinct genus of carnivorous theropod dinosaur from the Late Jurassic. Fossils referred to the genus have been found in China, Asia in the Oxfordian-?Tithonian. Its type species is based on several undiagnostic teeth from the Kuangyuan Series. Additional possible specimens of Szechuanosaurus were also reported from the Kalaza Formation, also located in China.

<i>Nanosaurus</i> Extinct genus of dinosaurs

Nanosaurus is an extinct genus of neornithischian dinosaur that lived about 155 to 148 million years ago, during the Late Jurassic in North America. Its fossils are known from the Morrison Formation of the south-western United States. The type and only species, Nanosaurus agilis, was described and named by Othniel Charles Marsh in 1877. The taxon has a complicated taxonomic history, largely the work of Marsh and Peter M. Galton, involving the genera Laosaurus, Hallopus, Drinker, Othnielia, and Othnielosaurus, the latter three now being considered to be synonyms of Nanosaurus. It had historically been classified as a hypsilophodont or fabrosaur, types of generalized small bipedal herbivore, but more recent research has abandoned these groupings as paraphyletic and Nanosaurus is today considered a basal member of Neornithischia.

<i>Marshosaurus</i> Extinct genus of dinosaurs

Marshosaurus is a genus of medium-sized carnivorous theropod dinosaur, belonging to the family Piatnitzkysauridae, from the Late Jurassic Morrison Formation of Utah and possibly Colorado.

<i>Camarasaurus lentus</i> Species of sauropod

Camarasaurus lentus is an extinct species of sauropod dinosaur that lived during the Jurassic period in what is now the western United States. It is one of the four valid species of the well-known genus Camarasaurus. C. lentus fossils have been found in Wyoming, Colorado, and Utah. It is the species of Camarasaurus found in Dinosaur National Monument and the middle layers of the Morrison Formation. Camarasaurus lentus is among the best-known sauropod species, with many specimens known. A juvenile specimen of C. lentus, CM 11338, is the most complete sauropod fossil ever discovered.

<i>Uteodon</i> Genus of reptiles (fossil)

Uteodon is a genus of herbivorous iguanodontian dinosaur. It is a basal iguanodontian which lived during the late Jurassic period in what is now Uintah County, Utah. It is known from the middle of the Brushy Basin Member, Morrison Formation. The genus was named by Andrew T. McDonald in 2011 and the type species is U. aphanoecetes.

<i>Oceanotitan</i> Extinct genus of dinosaurs

Oceanotitan is a genus of sauropod dinosaur known from the Upper Jurassic Lourinha Formation of Portugal. It is represented by a single specimen consisting of several tail vertebrae and appendicular bones. It contains one species, Oceanotitan dantasi. Oceanotitan is classified as possibly one of the earliest members of the Somphospondyli, a group of sauropods that includes the titanosaurs.

<i>Ardetosaurus</i> Genus of diplodocid sauropod dinosaurs

Ardetosaurus is an extinct genus of diplodocid sauropod dinosaurs from the Late Jurassic (Kimmeridgian) Morrison Formation of northern Wyoming, United States. The genus contains a single species, Ardetosaurus viator. It was first described in 2024 on the basis of a partial articulated skeleton, including vertebrae from the neck, back, and tail, hip bones, and part of the left hindlimb. The genus is a member of the Diplodocinae, a subfamily of large long-necked dinosaurs with whiplike tails. Ardetosaurus represents one of many distinct sauropod taxa that coexisted in this formation.

References

  1. ↑ Ray, G.E., 1941, "Big for his day", Natural History48: 36–39
  2. ↑ Lucas, S.G., Mateer, N.J., Hunt, A.P., and O'Neill, F.M., 1987, "Dinosaurs, the age of the Fruitland and Kirtland Formations, and the Cretaceous-Tertiary boundary in the San Juan Basin, New Mexico", p. 35-50. In: Fassett, J.E. and Rigby, J.K., Jr. (eds.), The Cretaceous-Tertiary boundary in the San Juan and Raton Basins, New Mexico and Colorado. GSA Special Paper 209
  3. ↑ W. Swainson and J. Richardson, 1831, Fauna boreali-americana, or, The zoology of the northern parts of British America: containing descriptions of the objects of natural history collected on the late northern land expeditions under command of Captain Sir John Franklin, R.N. Part 2, Birds, London, J. Murray
  4. 1 2 3 Chure, Daniel J. (1995). "A reassessment of the gigantic theropod Saurophagus maximus from the Morrison Formation (Upper Jurassic) of Oklahoma, USA". In A. Sun; Y. Wang (eds.). Sixth Symposium on Mesozoic Terrestrial Ecosystems and Biota, Short Papers. Beijing: China Ocean Press. pp. 103–106.
  5. ↑ Chure, D., 2000, A new species of Allosaurus from the Morrison Formation of Dinosaur National Monument (Utah-Colorado) and a revision of the theropod family Allosauridae. Ph.D. dissertation, Columbia University, pp. 1–964
  6. 1 2 Danison, Andrew; Wedel, Mathew; Barta, Daniel; Woodward, Holly; Flora, Holley; Lee, Andrew; Snively, Eric (December 21, 2024). "Chimerism in specimens referred to Saurophaganax maximus reveals a new species of Allosaurus (Dinosauria, Theropoda)". Vertebrate Anatomy Morphology Palaeontology. 12. doi: 10.18435/vamp29404 . ISSN   2292-1389.
  7. ↑ Smith, David K. (1998). "A morphometric analysis of Allosaurus". Journal of Vertebrate Paleontology. 18 (1): 126–142. Bibcode:1998JVPal..18..126S. doi:10.1080/02724634.1998.10011039.
  8. ↑ Holtz, Thomas R. Jr.; Molnar, Ralph E.; Currie, Philip J. (2004). Weishampel, David B.; Dodson, Peter; Osmólska, Halszka (eds.). The Dinosauria (2nd ed.). Berkeley: University of California Press. pp. 71–110. ISBN   978-0-520-24209-8.
  9. ↑ Carrano, Matthew T.; Benson, Roger B. J.; Sampson, Scott D. (June 1, 2012). "The phylogeny of Tetanurae (Dinosauria: Theropoda)". Journal of Systematic Palaeontology. 10 (2): 211–300. Bibcode:2012JSPal..10..211C. doi:10.1080/14772019.2011.630927. ISSN   1477-2019. S2CID   85354215.
  10. ↑ Foster, John (2007). Jurassic West: the Dinosaurs of the Morrison Formation and Their World. Bloomington, Indiana:Indiana University Press. p. 117.
  11. ↑ Rauhut, Oliver W. M.; Pol, Diego (December 11, 2019). "Probable basal allosauroid from the early Middle Jurassic Cañadón Asfalto Formation of Argentina highlights phylogenetic uncertainty in tetanuran theropod dinosaurs". Scientific Reports. 9 (1): 18826. doi:10.1038/s41598-019-53672-7. ISSN   2045-2322. PMC   6906444 . PMID   31827108. Supplementary information
  12. ↑ Trujillo, K.C.; Chamberlain, K.R.; Strickland, A. (2006). "Oxfordian U/Pb ages from SHRIMP analysis for the Upper Jurassic Morrison Formation of southeastern Wyoming with implications for biostratigraphic correlations". Geological Society of America Abstracts with Programs. 38 (6): 7.
  13. ↑ Bilbey, S.A. (1998). "Cleveland-Lloyd Dinosaur Quarry – age, stratigraphy and depositional environments". In Carpenter, K.; Chure, D.; Kirkland, J.I. (eds.). The Morrison Formation: An Interdisciplinary Study. Modern Geology 22. Taylor and Francis Group. pp. 87–120. ISSN   0026-7775.
  14. ↑ Russell, Dale A. (1989). An Odyssey in Time: Dinosaurs of North America. Minocqua, Wisconsin: NorthWord Press. pp. 64–70. ISBN   978-1-55971-038-1.
  15. ↑ Foster, J. (2020). Jurassic West, Second Edition: The Dinosaurs of the Morrison Formation and Their World (Life of the Past). Indiana University Press. ISBN   9780253051578.
  16. ↑ Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327–329.
  17. ↑ Foster, John R. (2003). Paleoecological Analysis of the Vertebrate Fauna of the Morrison Formation (Upper Jurassic), Rocky Mountain Region, U.S.A. New Mexico Museum of Natural History and Science Bulletin, 23. Albuquerque, New Mexico: New Mexico Museum of Natural History and Science. p. 29.
  18. ↑ Carpenter, Kenneth (2006). "Biggest of the big: a critical re-evaluation of the mega-sauropod Amphicoelias fragillimus". In Foster, John R.; Lucas, Spencer G. (eds.). Paleontology and Geology of the Upper Jurassic Morrison Formation. New Mexico Museum of Natural History and Science Bulletin, 36. Albuquerque, New Mexico: New Mexico Museum of Natural History and Science. pp. 131–138.

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