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Saurophaganax

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"Saurophagus maximus" redirects here. For the bird, seeSaurophagus.

Saurophaganax
Temporal range:Late Jurassic(Tithonian),
151Ma
↓
Reconstructed skeleton at theSam Noble Oklahoma Museum of Natural History
Scientific classificationEdit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Clade: †Carnosauria
Superfamily: †Allosauroidea
Genus: †Saurophaganax
Chure, 1995
Species:
†S. maximus
Binomial name
†Saurophaganax maximus
Chure, 1995
Synonyms

Saurophaganax( "lord of lizard-eaters" ) is agenusof largeallosauroiddinosaurfrom theMorrison FormationofLate Jurassic(latestKimmeridgianage, about 151 million years ago)Oklahoma,United States.[1]Some paleontologists consider it to be a junior synonym and species ofAllosaurus(asA. maximus).Saurophaganaxrepresents a very large Morrison allosauroid characterized by horizontal laminae at the bases of the dorsal neural spines above the transverse processes, and "meat-chopper"chevrons.[2]It was the largest terrestrial carnivore of North America during the Late Jurassic, reaching 10.5 metres (34 ft) in length and 2.7–3.8 metric tons (3.0–4.2 short tons) in body mass.

Discovery and naming

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A drawer ofSaurophaganaxvertebrae, Oklahoma Museum of Natural History

In 1931 and 1932,John Willis Stovalluncovered remains of a large theropod nearKentoninCimarron County,Oklahomain layers of the lateKimmeridgian.In 1941, these were namedSaurophagus maximusby Stovall in an article by journalistGrace Ernestine Ray.[3]The generic name is derived from Greekσαυρος,sauros,"lizard",φάγειν,phagein,"to eat", with the compound meaning of "lizard eater". Thespecific epithetmaximusmeans "the largest" inLatin.Because the naming article did not contain a description, the name remained anomen nudum.In 1987,Spencer George Lucaserroneously made OMNH 4666, atibia,thelectotype,unaware thatSaurophaguswas anomen nudum.[4]

Later, it was discovered that the nameSaurophaguswas preoccupied: in 1831, it had already been given byWilliam Swainsontoa tyrant-flycatcher,an extant eater of taxonomically true lizards.[5]In 1995,Daniel Churenamed a new genus:Saurophaganax,adding Greek suffix -άναξ,anax,meaning "ruler", to the earlier name. Chure also found OMNH 4666 undiagnostic in relation toAllosaurus,so he chose OMNH 01123, aneural arch,as the holotype forSaurophaganax.[6]— andSaurophaganaxis not a renaming of "Saurophagus".[7]Much of the material informally named "Saurophagus maximus", namely those diagnostic elements that could be distinguished fromAllosaurus,were referred toSaurophaganax maximusby Chure. They contain disarticulated bones of at least four individuals.[7]

Saurophaganaxis the officialstate fossilofOklahoma,[8]and a large skeleton ofSaurophaganaxcan be seen in the Jurassic hall in theSam Noble Oklahoma Museum of Natural History.Although the best knownSaurophaganaxmaterial was found in the panhandle of Oklahoma, possibleSaurophaganaxmaterial, NMMNH P-26083, a partial skeleton including a femur, several tail vertebrae, and a hip bone, has been found in northernNew Mexico.[9]

Relationship withAllosaurus

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The identification ofSaurophaganaxis a matter of dispute. It has been described as its own genus,[7]or as a species ofAllosaurus:Allosaurus maximus.[10]A review of basal tetanurans in 2004 and Carrano et al.'s comprehensive 2012 analysis of Tetanurae acceptedSaurophaganaxas a distinct genus.[11][12]PossibleSaurophaganaxmaterial from New Mexico may clear up the status of the genus.[9]In 2019, Rauhut and colleagues noted that the definitive taxonomic placement ofSaurophaganaxwithinAllosauroideais unstable, being recovered as a sister taxon ofMetriacanthosauridaeor Allosauria, or even as a basalmost carcharodontosaurian.[13]In 2024,Saurophaganaxwas recovered as a sister taxon of themetriacanthosauridYangchuanosaurus shangyouensis,indicating that the genus might be ametriacanthosauridinstead of an allosaurid.[14]

Description

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Size comparison

Saurophaganaxwas the largest carnivore found in theMorrison Formation,bigger than both its contemporariesTorvosaurus tanneriandAllosaurus fragilis,reaching 10.5 metres (34 ft) in length and 2.7–3.8 metric tons (3.0–4.2 short tons) in body mass.[15][16][17][18]

Paleoecology

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Life reconstruction

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,[19]to 146.8 million years old at the top,[20]which places it in the lateOxfordian,Kimmeridgian,and earlyTithonianstagesof the Late Jurassic period. This formation is interpreted as asemiaridenvironment with distinctwetanddry seasons.The Morrison Basin where dinosaurs lived, stretched from New Mexico to Alberta and Saskatchewan, and was formed when the precursors to theFront Rangeof the Rocky Mountains started pushing up to the west. The deposits from their east-facingdrainage basinswere carried by streams andriversand deposited inswampylowlands, lakes, river channels andfloodplains.[21]This formation is similar in age to theSolnhofen LimestoneFormation inGermanyand theTendaguru FormationinTanzania.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.[22]

Mounted skeleton posed attacking aDiplodocus,New Mexico Museum of Natural History & Science.

The Morrison Formation records an environment and time dominated by gigantic sauropod dinosaurs such asBarosaurus,Apatosaurus,Brontosaurus,Camarasaurus,Diplodocus,andBrachiosaurus.Dinosaurs that lived alongsideSaurophaganax,and may have served as prey, included the herbivorousornithischiansCamptosaurus,Dryosaurus,Stegosaurus,andNanosaurus.Predators in this paleoenvironment included thetheropodsTorvosaurus,Ceratosaurus,Marshosaurus,Stokesosaurus,Ornitholestes,and[23]Allosaurus,which accounted for 70 to 75% of theropod specimens and was at the toptrophic levelof the Morrisonfood web.[24]Other vertebrates that shared this paleoenvironment includedray-finned fishes,frogssuch asEobatrachus,salamanders,turtles,sphenodonts,lizards,terrestrial and aquaticcrocodylomorphslikeGoniopholis,and several species ofpterosaurlikeKepodactylus.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 fernsavannaswith occasional trees such as theAraucaria-like coniferBrachyphyllum.[25]In Oklahoma, Stovall unearthed a considerable number ofApatosaurusspecimens, which may have represented possible prey for a large theropod likeSaurophaganax.

Bite marks onAllosaurusandMymoorapeltaremains were found among other bones with feeding traces in the Upper Jurassic Mygatt-Moore Quarry. Unlike the others, these have left striations that, when measured to determine denticle width, produced tooth and body size extrapolations greater than any known specimen ofAllosaurusorCeratosaurus,the two large predators known for osteological remains from the quarry. The extrapolations are instead coherent either with an unusually large specimen ofAllosaurus,or a separate large taxon likeTorvosaurusorSaurophaganax,both of which are not known from the quarry.The result either increases the known diversity of the site based on ichnological evidence alone, or represents powerful evidence of cannibalism inAllosaurus.Based on the position and nutrient value associated with the various skeletal elements with bite marks, it is predicted that whileMymoorapeltawas either predated upon or scavenged shortly after death,Allosauruswas scavenged some time after death.[26]

References

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  1. ^Turner, C.E. and Peterson, F., (1999). "Biostratigraphy of dinosaurs in the Upper Jurassic Morrison Formation of the Western Interior, U.S.A." Pp. 77–114 in Gillette, D.D. (ed.),Vertebrate Paleontology in Utah.Utah Geological Survey Miscellaneous Publication 99-1.
  2. ^Glut, Donald F. (1997). "Saurophagus".Dinosaurs: The Encyclopedia.Jefferson, North Carolina: McFarland & Co. pp. 793–794.ISBN978-0-89950-917-4.
  3. ^Ray, G.E., 1941, "Big for his day",Natural History48:36–39
  4. ^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
  5. ^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
  6. ^Chure, D., 2000,A new species ofAllosaurusfrom 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
  7. ^abcChure, Daniel J. (1995). "A reassessment of the gigantic theropodSaurophagus maximusfrom 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.
  8. ^"OK State Symbols".OkInsider.Oklahoma Publishing Today. 2006. Archived fromthe originalon August 7, 2007.RetrievedDecember 27,2007.
  9. ^abFoster, John (2007).Jurassic West: the Dinosaurs of the Morrison Formation and Their World.Bloomington, Indiana:Indiana University Press. p. 117.
  10. ^Smith, David K. (1998). "A morphometric analysis ofAllosaurus".Journal of Vertebrate Paleontology.18(1): 126–142.Bibcode:1998JVPal..18..126S.doi:10.1080/02724634.1998.10011039.
  11. ^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.ISBN978-0-520-24209-8.
  12. ^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.ISSN1477-2019.S2CID85354215.
  13. ^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.ISSN2045-2322.PMC6906444.PMID31827108.Supplementary information
  14. ^Cau, A. (2024)."A Unified Framework for Predatory Dinosaur Macroevolution".Bollettino della Società Paleontologica Italiana.63(1).doi:10.4435/BSPI.2024.08.Supplementary Material
  15. ^Farlow, J. O.; Coroian, D.; Currie, P.J.; Foster, J.R.; Mallon, J.C.; Therrien, F. (2022).""Dragons" on the landscape: Modeling the abundance of large carnivorous dinosaurs of the Upper Jurassic Morrison Formation (USA) and the Upper Cretaceous Dinosaur Park Formation (Canada) ".The Anatomical Record.306(7): 1669–1696.doi:10.1002/ar.25024.PMID35815600.
  16. ^Paul, G. S.(2010).The Princeton Field Guide to Dinosaurs.Princeton University Press. pp.96.ISBN978-0-691-13720-9.
  17. ^Persons, S. W.; Currie, P. J.; Erickson, G. M. (2020)."An Older and Exceptionally Large Adult Specimen ofTyrannosaurus rex".The Anatomical Record.303(4): 656–672.doi:10.1002/ar.24118.ISSN1932-8486.PMID30897281.
  18. ^Campione, Nicolás E.; Evans, David C. (2020)."The accuracy and precision of body mass estimation in non-avian dinosaurs".Biological Reviews.95(6): 1759–1797.doi:10.1111/brv.12638.ISSN1469-185X.PMID32869488.S2CID221404013.
  19. ^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.
  20. ^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 Geology22.Taylor and Francis Group. pp. 87–120.ISSN0026-7775.
  21. ^Russell, Dale A.(1989).An Odyssey in Time: Dinosaurs of North America.Minocqua, Wisconsin: NorthWord Press. pp. 64–70.ISBN978-1-55971-038-1.
  22. ^Foster, J. (2020).Jurassic West, Second Edition: The Dinosaurs of the Morrison Formation and Their World (Life of the Past).Indiana University Press.ISBN9780253051578.
  23. ^Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327–329.
  24. ^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.
  25. ^Carpenter, Kenneth(2006). "Biggest of the big: a critical re-evaluation of the mega-sauropodAmphicoelias 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.
  26. ^Drumheller, Stephanie K.; McHugh, Julia B.; Kane, Miriam; Riedel, Anja; D’Amore, Domenic C. (May 27, 2020)."High frequencies of theropod bite marks provide evidence for feeding, scavenging, and possible cannibalism in a stressed Late Jurassic ecosystem".PLOS ONE.15(5): e0233115.Bibcode:2020PLoSO..1533115D.doi:10.1371/journal.pone.0233115.ISSN1932-6203.PMC7252595.PMID32459808.

Sources

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Wikimedia Commons has media related toSaurophaganax.
Wikispecieshas information related toSaurophaganax.
  • Dixon, Dougal.The World Encyclopedia of Dinosaurs and Prehistoric Creatures.
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