Open Paleo

Tyrannosaurus

Osborn, 1905 ti-RAN-o-SAWR-us /tɪˌrænəˈsɔːrəs/

From Greek tyrannos (tyrant) and sauros (lizard); meaning "tyrant lizard", a name Osborn coined to convey the genus's exceptional size relative to all then-known carnivorous land vertebrates.

72.2–66.0 million years ago Maastrichtian, Late Cretaceous
Late Cretaceous stages

Tyrannosaurus is a genus of large theropod dinosaur. The type species Tyrannosaurus rex (rex meaning 'king' in Latin), often shortened to T. rex, is one of the best represented theropods. It lived throughout what is now western North America, on what was then an island continent known as Laramidia, and had a much wider range than other tyrannosaurids. Fossils are found in a variety of geological formations dated to the late Maastrichtian age of the Late Cretaceous period, 69 to 66 million years ago, with isolated specimens possibly indicating an earlier origin in the middle Campanian age. It was one of the last known members of the tyrannosaurids and among the last non-avian dinosaurs to exist before the Cretaceous-Paleogene extinction event.

Diagnosis

  1. Megalocephalic skull with deep, massively built proportions, brought close to the sacrum by a shortened presacral column of approximately 23 vertebrae.
  2. Fused nasals forming an arched midline ridge on the snout that reinforces the skull against bite-induced stress.
  3. Teeth heterodont and broadly oval to D-shaped in cross-section, with transverse diameter exceeding anteroposterior; alveolar reinforcing plates on the inner surface of the maxilla and dentary.
  4. Squamosal bearing a distinctive horizontal anterior bar projecting into the laterotemporal fenestra.
  5. Forelimb extremely reduced; functionally didactyl manus with powerful recurved unguals; humerus little more than half the length of the femur.
  6. Five sacral vertebrae coossified into a single neural plate with three small fenestrations between S2 and S5.
  7. Pubis, ilium and ischium firmly coalesced; pubis terminating distally in a hugely expanded pedicle ("pubic boot").
  8. Caudal series of approximately 53 vertebrae forming a long, flexible balancing tail without the rod-like rigidity of ornithomimids.

Species

Tyrannosaurus rex Osborn, 1905

Type species

From Latin rex, "king", chosen by Osborn to evoke the animal's standing as the largest carnivorous land vertebrate then known.

Holotype
CM 9380 , Carnegie Museum of Natural History
Material
Partial skeleton with both jaws and portions of the skull, vertebrae, ribs, scapula, humerus, ilium, pubis, ischium, and metapodials.
Horizon
Hell Creek Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
Locality
Quarry No. 1, near Jordan, Montana, United States

Synonyms

  • Dinotyrannus megagracilis junior subjective

    Erected by Olshevsky (1995) as a new genus for Albertosaurus megagracilis Paul, 1988. Currie and colleagues (2003) judged the material probably a juvenile Tyrannosaurus rex and later work has followed, though Longrich and Saitta (2024) refer it only to Tyrannosaurus indet.

  • Dynamosaurus imperiosus junior subjective

    Erected by Osborn (1905) in the same paper as T. rex on AMNH 5866 from Wyoming; formally synonymized with T. rex by Osborn (1906) after direct comparison of the two type specimens.

  • Manospondylus gigas nomen oblitum

    Erected by Cope (1892) on two dorsal vertebrae from the Hell Creek Formation of South Dakota; treated as indeterminate by Osborn (1917). The name is technically senior to Tyrannosaurus rex but, having been used in fewer than 25 publications since 1899, is suppressed under ICZN Article 23.9 in favor of Tyrannosaurus rex (nomen protectum).

Notable specimens

  • “Sue”

    FMNH PR2081 Field Museum of Natural History Found 1990 by Sue Hendrickson most complete

    The most complete (about 85 percent) and largest Tyrannosaurus skeleton, from the Hell Creek Formation. Histology shows it reached full size at age 19 and died at about 28, the longest estimated life of any tyrannosaur known.

    Brochu (2003)

  • “Stan”

    NHMAD 2020.00001, BHI 3033 Natural History Museum Abu Dhabi Found 1992 by Stan Sacrison pathology

    The second most complete Tyrannosaurus skeleton, 199 bones representing 70 percent of the total, from the Hell Creek Formation. Its pathologies include broken and healed ribs, a broken and healed neck, and a hole in the back of the head about the size of a Tyrannosaurus tooth.

    Wolff et al. (2009)Tanke & Currie (1998)

  • “Scotty”

    RSM P2523.8 Royal Saskatchewan Museum largest individual

    Reported to measure 13 meters in length. Using a mass estimation technique extrapolating from femur circumference, Scotty was estimated as the largest known Tyrannosaurus specimen at 8.87 t in body mass.

    Persons et al. (2019)

  • “B-rex”

    MOR 1125 Museum of the Rockies reproductive

    From the Hell Creek Formation. Yielded medullary tissue in its femur, found only in female birds during ovulation, confirming it as a female that died during ovulation; the only Tyrannosaurus conclusively sexed. Also a source of reported soft-tissue blood vessels and collagen.

    Schweitzer et al. (2005)

  • “Wyrex”

    HMNS 2006.1743.01, BHI 6230 Houston Museum of Nature and Science Found 2002 by Dan Wells and Don Wyrick exceptional preservation

    Preserves patches of mosaic scales on the tail, hip, and neck, used in a 2017 review concluding that feather covering of large tyrannosaurids, if present, was limited to the upper side of the trunk. Also shows pathologies: a hole penetrating its jugal and severe tail trauma with bone remodeling.

    Bell et al. (2017)

  • “Wankel rex”

    MOR 555 Museum of the Rockies complementary

    The first complete Tyrannosaurus forelimbs were identified in 1989 belonging to MOR 555, confirming that the genus had short two-fingered arms about 1 meter long, as had been suggested from the related Gorgosaurus.

    Carpenter & Smith (2001)

References

  1. Larson, N. L. (2008). One Hundred Years of Tyrannosaurus rex: The Skeletons. Tyrannosaurus rex, the Tyrant King (Larson, P.; Carpenter, K., eds.) 1-55. Indiana University Press, Bloomington.

    Gives the holotype as "From Quarry No. 1, near Jordan, Garfield County, MT (Osborn 1905)".

    larson2008a
  2. Brochu, C. R. (2003). Osteology of Tyrannosaurus rex: insights from a nearly complete skeleton and high-resolution computed tomographic analysis of the skull. Society of Vertebrate Paleontology Memoirs 7: 1-138. doi:10.2307/3889334 brochu2003a
  3. Wolff, E. D. S.; Salisbury, S. W.; Horner, J. R.; Varricchio, D. J. (2009). Common avian infection plagued the tyrant dinosaurs. PLOS ONE 4(9): e7288. Public Library of Science (PLoS). doi:10.1371/journal.pone.0007288 wolff2009a
  4. Tanke, D. H.; Currie, P. J. (1998). Head-biting behavior in theropod dinosaurs: paleopathological evidence. Gaia 15(15): 167-184. tanke1998a
  5. Persons, S. W.; Currie, P. J.; Erickson, G. M. (2019). An older and exceptionally large adult specimen of Tyrannosaurus rex. The Anatomical Record 303(4): 656-672. doi:10.1002/ar.24118 persons2019a
  6. Schweitzer, M. H.; Wittmeyer, J. L.; Horner, J. R. (2005). Gender-specific reproductive tissue in ratites and Tyrannosaurus rex. Science 308(5727): 1456-1460. doi:10.1126/science.1112158 schweitzer2005a
  7. Bell, P. R.; Campione, N. E.; Persons, W. S., IV; Currie, P. J.; Larson, P. L.; Tanke, D. H.; Bakker, R. T. (2017). Tyrannosauroid integument reveals conflicting patterns of gigantism and feather evolution. Biology Letters 13(6): 20170092. doi:10.1098/rsbl.2017.0092 bell2017a
  8. Carpenter, K.; Smith, M. (2001). Forelimb osteology and biomechanics of Tyrannosaurus rex. Mesozoic Vertebrate Life: New Research Inspired by the Paleontology of Philip J. Currie (Tanke, D. H.; Carpenter, K., eds.) 90-116. Indiana University Press, Bloomington. carpenter2001c
  9. Osborn, H. F. (1905). Tyrannosaurus and other Cretaceous carnivorous dinosaurs. Bulletin of the American Museum of Natural History 21(14): 259-265. doi:10.5281/zenodo.814935

    Erects Tyrannosaurus rex on AMNH 973 (now CM 9380) from the Hell Creek Formation of Dawson County, Montana, and in the same paper names Dynamosaurus imperiosus and Albertosaurus sarcophagus.

    osborn1905a
  10. Osborn, H. F. (1906). Tyrannosaurus, Upper Cretaceous carnivorous dinosaur (second communication). Bulletin of the American Museum of Natural History 22: 281-296.

    Refines the T. rex skull description and formally synonymizes Dynamosaurus imperiosus with Tyrannosaurus.

    osborn1906a
  11. Osborn, H. F. (1917). Skeletal adaptations of Ornitholestes, Struthiomimus, Tyrannosaurus. Bulletin of the American Museum of Natural History 35(43): 733-771.

    First detailed monograph on the mounted AMNH 5027 referred skeleton; treats Manospondylus gigas as indeterminate and establishes the classic 20th-century Tyrannosaurus skeletal interpretation.

    osborn1917a
  12. Brusatte, S. L.; Norell, M. A.; Carr, T. D.; Erickson, G. M.; Hutchinson, J. R.; Balanoff, A. M.; Bever, G. S.; Choiniere, J. N.; Makovicky, P. J.; Xu, X. (2010). Tyrannosaur paleobiology: new research on ancient exemplar organisms. Science 329(5998): 1481-1485. doi:10.1126/science.1193304

    Modern multi-author review of tyrannosaur paleobiology; summarizes growth rate, bite force, ontogenetic skull change and locomotor modeling for T. rex.

    brusatte2010a
  13. Molina-Pérez, R.; Larramendi, A. (2019). Dinosaur Facts and Figures: The Theropods and Other Dinosauriformes. Princeton University Press.

    Source of the hip height estimate.

    molina-pérez2019a
  14. Paul, G. S. (2024). The Princeton Field Guide to Predatory Dinosaurs. Princeton University Press.

    Source of the appearance features.

    paul2024b
  15. Currie, P. J.; Hurum, J. H.; Sabath, K. (2003). Skull structure and evolution in tyrannosaurid dinosaurs. Acta Palaeontologica Polonica 48(2): 227-234. https://app.pan.pl/article/item/app48-227.html

    Judges the material of Albertosaurus megagracilis, renamed Dinotyrannus megagracilis, probably a juvenile Tyrannosaurus rex.

    currie2003a
  16. Cope, E. D. (1892). Fourth note on the Dinosauria of the Laramie. The American Naturalist 26(310): 756-758. University of Chicago Press. doi:10.1086/275585

    Named Manospondylus gigas, later declared a nomen oblitum relative to Tyrannosaurus.

    cope1892a
  17. Longrich, N. R.; Saitta, E. T. (2024). Taxonomic Status of Nanotyrannus lancensis (Dinosauria: Tyrannosauroidea) — A Distinct Taxon of Small-Bodied Tyrannosaur. Fossil Studies 2(1): 1-65. doi:10.3390/fossils2010001 longrich2024d
  18. Olshevsky, G.; Ford, T. L.; Yamamoto, S. (1995). The origin and evolution of the tyrannosaurids (Part 1). Kyoryugaku Saizensen 9: 92-119. olshevsky1995a