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User:LittleLazyLass/Ornithopoda

< User:LittleLazyLass

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Genus Tyrannosaurus

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T. rex

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Tyrannosaurus mcraeensis

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Reconstructed skull (top) and speculative life restoration (bottom) of T. mcraeensis

In 2024, Dalman and colleagues described the remains of a tyrannosaur discovered in 1983 in the Campanian-early Maastrichtian Hall Lake Formation in New Mexico. Reposited at the New Mexico Museum of Natural History and Science, the fossil material (NMMNH P-3698) consists of the right postorbital, right squamosal, left palatine, and an incomplete maxilla from the skull, the left dentary, right splenial, right prearticular, right angular and right articular from the lower jaws, isolated teeth, and chevrons.[1] Some of the bones were briefly mentioned in 1984 as belonging to T. rex,[2] and described in 1986.[3]

Lehman and Carpenter (1990) suggested that NMMNH P-3698 belonged to a new tyrannosaurid genus,[4] while Carr and Williamson (2000) disagreed with their claim.[5] Sullivan and Lucas (2015) argued that there is little evidence to support NMMNH P-3698 as a specimen of Tyrannosaurus rex, so they tentatively classified it as cf. Tyrannosaurus sp.; they also considered that the McRae tyrannosaur lived before the Lancian (before 67 million years ago) based on its probable association with the Alamosaurus fossil.[6]

Mandibular elements of the T. mcraeensis holotype

Dalman et al. (2024) proposed the new name Tyrannosaurus mcraeensis for the holotype (NMMNH P-3698), referencing the McRae Group, the rock layers to which the Hall Lake Formation belongs. The holotype of T. mcraeensis is found in the strata that are around a few million years older than the accepted range of T. rex, which existed at the end of the Maastrichtian. The rock layers were initially estimated to date to between 72.7 and 70.9 Ma, correlating to the latest Campanian or earliest Maastrichtian.[1] However, in a 2024 conference abstracts, the specific stratigraphic layer which yielded T. mcraeensis was estimated to be younger than 69.0 ± 0.4 Ma and older than 66.0 Ma based on the sandstone from the same fossil locality,[7] which would suggest that the age of T. mcraeensis is much closer to T. rex than previously thought.[8] T. mcraeensis was estimated at 12 metres (39 ft) long, which is similar to the size of an adult T. rex. The two are distinguished by characters of the skull. Amongst these, the dentary of T. mcraeensis is proportionately longer and possesses a less prominent chin, and the lower jaw shallower than that of T. rex, suggesting a weaker bite. The teeth are likewise blunter and more laterally compressed, while the post orbital crests are less prominent. Likewise, the skeletal anatomy showcases shared characteristics with Tarbosaurus and Zhuchengtyrannus.[1][9]

The validity of T. mcraeensis was subsequently questioned by other researchers in 2025. Morrison and colleagues noted the uncertainty in the previous age estimate of T. mcraeensis. The authors argued that the inclusion of the titanosaurian fossil (cf. Alamosaurus) as a biostratigraphic marker of the Hall Lake Formation fauna makes the dating problematic due to the fossil having a huge variability in assumed sedimentation rates. The study also suggested the uncertainty in the morphology of T. mcraeensis holotype being reliably outside the known variation of T. rex. Regardless of the age and validity of T. mcraeensis, the authors concluded that the genus Tyrannosaurus still most likely originated from Laramidia and that the ancestors of this genus possibly migrated from Asia.[10] Later that year, Voris and colleagues regarded T. mcraeensis as a junior synonym of T. rex, agreeing with the problematic stratigraphic data and finding all of the proposed diagnostic characters of T. mcraeensis to be in the known T. rex specimen range of variation.[11] In his study of the T. rex holotype skull, Carr also did not regard T. mcraeensis as a valid species, agreeing with the proposed characters of the T. mcraeensis holotype being visible throughout the hypodigm of T. rex.[12]

Multispecies models

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Early suggestions

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t. vanus

t. stanwinstonorum

t. x

etc

Tyrannosaurus imperator and Tyrannosaurus regina

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In a 2022 study, Gregory S. Paul and colleagues argued that Tyrannosaurus rex, as traditionally understood, actually represents three species: the type species Tyrannosaurus rex, and two previously unrecognized species: T. imperator (meaning "tyrant lizard emperor") and T. regina (meaning "tyrant lizard queen"). The holotype of the former (T. imperator) is the Sue specimen, and the holotype of the latter (T. regina) is Wankel rex. The division into multiple species was primarily based on the high degree of variation in the proportions and robusticity of the femur (and other skeletal elements) across T. rex specimens. Presumed robust and gracile morphotypes and the number of small incisiform teeth in the dentary were also used as a line of evidence. Paul and colleagues categorized the species as follows: T. rex demonstrates robust anatomy, a moderate ratio of femur length vs circumference, and the possession of a singular slender incisiform dentary tooth, T. imperator is robust with a small femur length to circumference ratio and two of the slender teeth, and T. regina is more gracile with a high femur ratio and one of the slender teeth.[13]

However, several leading paleontologists, including Stephen Brusatte, Thomas Carr, Thomas Holtz, David Hone, Jingmai O'Connor, and Lindsay Zanno, criticized the study or expressed skepticism of its conclusions when approached by various media outlets for comment.[14][15][16] Their criticism was subsequently published in a technical paper.[17] Holtz and Zanno both remarked that it was plausible that more than one species of Tyrannosaurus existed, but felt the new study was insufficient to support the species it proposed. Holtz remarked that, even if Tyrannosaurus imperator represented a distinct species from Tyrannosaurus rex, it may represent the same species as Nanotyrannus lancensis and would need to be called Tyrannosaurus lancensis. O'Connor, a curator at the Field Museum, where the T. imperator holotype Sue is displayed, regarded the new species as too poorly-supported to justify modifying the exhibit signs. Brusatte, Carr, and O'Connor viewed the distinguishing features proposed between the species as reflecting natural variation within a species. Both Carr and O'Connor expressed concerns about the study's inability to determine which of the proposed species several well-preserved specimens belonged to. Another paleontologist, Philip J. Currie, originally co-authored the study but withdrew from it as he did not want to be involved in naming the new species.[14]

In a subsequent paper published in 2025, Paul maintained the validity of T. imperator and T. regina, arguing that these proposed species could be further distinguished by the shape of their postorbital bosses (bony rugosities behind the eyes).[18]

Potential juveniles

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Dinotyrannus

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content

Stygivenator

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Nanotyrannus

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Cast of CMNH 7541, the holotype of Nanotyrannus lancensis, sometimes interpreted as a juvenile Tyrannosaurus.

Other tyrannosaur fossils found in the same formations as T. rex were originally classified as separate taxa, including Aublysodon and Albertosaurus megagracilis,[19] the latter being named Dinotyrannus megagracilis in 1995.[20] These fossils are now universally considered to belong to juvenile T. rex.[21] A small but nearly complete skull from Montana, 57.2 centimeters (1.88 ft) long, is an exception. This skull, CMNH 7541, was originally classified as a species of Gorgosaurus (G. lancensis) by Charles W. Gilmore in 1946.[22] In 1988, the specimen was re-described by Robert T. Bakker, Michael Williams, then the curator of paleontology at the Cleveland Museum of Natural History, and Phil Currie, where the original specimen was housed and is now on display. Their initial research indicated that the skull bones were fused, and that it therefore represented an adult specimen. In light of this, Bakker and colleagues assigned the skull to a new genus named Nanotyrannus (meaning "dwarf tyrant", for its apparently small adult size).[23] However, in 1999, a detailed analysis by Thomas Carr revealed the specimen to be a juvenile, leading Carr and many other paleontologists to consider it a juvenile T. rex individual.[24][25]

Reconstructed skeleton of "Jane", Burpee Museum of Natural History

In 2001, a more complete juvenile tyrannosaur (nicknamed "Jane", accession number BMRP 2002.4.1), suggested to belong to the same species as the original Nanotyrannus specimen, was uncovered. This discovery prompted a conference on tyrannosaurs focused on the issues of the validity of Nanotyrannus, held at the Burpee Museum of Natural History in 2005. Several paleontologists who had previously published opinions that N. lancensis was a valid species, including Currie and Williams, saw the discovery of "Jane" as a confirmation that Nanotyrannus was, in fact, a juvenile T. rex.[26][27][28] Peter Larson continued to support the hypothesis that Nanotyrannus lancensis was a separate but closely related species, and also argued that Stygivenator (LACM 28471), which is generally considered to be a juvenile of Tyrannosaurus rex, could be a younger specimen of Nanotyrannus.[29][30]

In late 2011, news reports about a 2006 discovery of a new, virtually complete theropod specimen found alongside a ceratopsid were made. The specimens were studied by Robert Bakker and Peter Larson on-site, who identified the ceratopsian as Triceratops and the theropod as Nanotyrannus.[31] It was impossible to determine whether the theropod specimen, nicknamed "Bloody Mary", was distinct from T. rex, as the specimen remained in private hands until 2020, when the ownership of the specimen was decided by the Montana Supreme Court to be given to the landowners Mary Anne and Lige Murray, who agreed to sell the paired fossils to a U.S.-based museum.[32] The fossil was acquired by the North Carolina Museum of Natural Sciences in 2020, after which the museum built an additional research lab space in which to prepare, study, and display the specimens.[33][34] In 2025, paleontologists Lindsay Zanno and James Napoli published an initial description of the "Bloody Mary" specimen as part of an extensive revision of the genus Nanotyrannus. They identified this specimen as a skeletally mature individual of Nanotyrannus and provided several lines of evidence supporting the validity of this genus. They also described a second species, N. lethaeus, based on the Jane specimen due to notable differences between it and N. lancensis.[35]


Other possible material

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Asian material

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Diagram showing the differences between a generalized Tarbosaurus (A) and Tyrannosaurus rex (B) skull

In 1955, Soviet paleontologist Evgeny Maleev named a new species, Tyrannosaurus bataar, from Mongolia.[36] By 1965, this species was renamed as a distinct genus, Tarbosaurus bataar.[37] While most paleontologists continue to maintain the two as distinct genera, some authors such as Thomas Holtz, Kenneth Carpenter, and Thomas Carr argue that the two species are similar enough to be considered members of the same genus, restoring the Mongolian taxon's original binomial name.[38][39][40]

Some specimens from the Late Cretaceous deposits of China have been described as new species of Tyrannosaurus: T. "lanpingensis" based on isolated lateral tooth from the red beds of Yunnan in 1975; T. "turpanensis" from the Subashi Formation, Turpan Basin, Xinjiang in 1978; and T. luanchuanensis from the Quiba Formation, Tantou Basin, Henan Province in 1979–1980.[41][42][43] The former two taxa were published without detailed descriptions and are therefore nomina nuda. T. "turpanensis" and T. luanchuanensis were tentatively listed as junior synonyms of Tarbosaurus bataar by Holtz in 2004; Holtz also listed T. "lanpingensis," but as a nomen dubium.[44][42][43]

VGI, no. 231/3, a large phalanx bone, assigned to Tyrannosaurus sp. by Yarkov in 2000, was found in the Lower Maastrichtian of Bereslavka, Russia. In 2004, Averianov and Yarkov reinterpreted it as a metacarpal I or metatarsal I that possibly belongs to ceratosaur.[45] In their 2023 overview, Averianov and Lopatin mention this specimen as well as a single tooth from the same site only as Theropoda indet.[46]

In 2001, various tyrannosaurid teeth and a metatarsal unearthed in a quarry near Zhucheng, China, were assigned by Chinese paleontologist Hu Chengzhi to the newly erected species Tyrannosaurus zhuchengensis. However, in a nearby site, a right maxilla and left jawbone were assigned to the newly erected tyrannosaurid genus Zhuchengtyrannus in 2011. It is possible that T. zhuchengensis is synonymous with Zhuchengtyrannus. In any case, T. zhuchengensis is considered to be a nomen dubium as the holotype lacks diagnostic features below the level Tyrannosaurinae.[47]

American material

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In 2006, a fragmentary tyrannosaurid lacrimal (CM 9401) from the Judith River Formation of Fergus County, Montana, was described as ?Tyrannosaurus sp. This isolated right lacrimal was originally collected alongside the holotype specimen of Deinosuchus rugosus, a giant crocodilian, and remained undescribed until its re-identification as belonging to a tyrannosaurid theropod in the 1980s by paleontologist Dale Russell. The lacrimal closely resembles those of Tyrannosaurus rex in both size and morphology. Notably, it lacks the "lacrimal horn" typically present in earlier tyrannosaurids like Albertosaurus and Gorgosaurus, instead exhibiting a distinct rugosity along the dorsal surface—consistent with T. rex and its Asian relative Tarbosaurus. The specimen's considerable size places it within the range of known T. rex individuals, suggesting the presence of large tyrannosaurids during the Campanian stage (~75 million years ago), a temporal range earlier than the established Maastrichtian age (~68–66 Ma) for Tyrannosaurus rex. However, the exact age and provenance of CM 9401 remain uncertain due to a lack of detailed field documentation.[48]

In 2018, a paper describing tyrannosaurid teeth from the Two Medicine Formation noted a premaxillary tooth (YPM VPPU 023469) had a strong resemblance to the teeth of Sue to the exclusion of any Campanian tyrannosaurid. Additionally, the authors of this paper suggested that CM 9401 also comes from the Two Medicine Formation, as there were preservational similarities between its locality and the Willow Creek anticline, which is where the tooth was found.[49] Notably, this would place both specimens in the Flag Butte Member of the Two Medicine Formation, which dates from 77 to 76.3 Ma, far older than any other Tyrannosaurus specimen, and directly contemporaneous with Daspletosaurus. In 2025, these specimens, with their old geologic age, were used as evidence by Charlie Scherer to suggest that the Tyrannosaurini did not evolve directly from Daspletosaurus.[8]

References

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  1. 1 2 3 Dalman, Sebastian G.; Loewen, Mark A.; Pyron, R. Alexander; Jasinski, Steven E.; Malinzak, D. Edward; Lucas, Spencer G.; Fiorillo, Anthony R.; Currie, Philip J.; Longrich, Nicholas R. (January 11, 2024). "A giant tyrannosaur from the Campanian–Maastrichtian of southern North America and the evolution of tyrannosaurid gigantism". Scientific Reports. 13 (1): 22124. doi:10.1038/s41598-023-47011-0. ISSN 2045-2322. PMC 10784284. PMID 38212342.
  2. ↑ Lozinsky, Richard P.; Hunt, Adrian P.; Wolberg, Donald L.; Lucas, Spencer G. (1984). "Late Cretaceous (Lancian) dinosaurs from the McRae Formation, Sierra County, New Mexico" (PDF). New Mexico Geology. 6 (4): 72–77. doi:10.58799/NMG-v6n4.72 (inactive July 12, 2025). ISSN 0196-948X. S2CID 237011797. Archived (PDF) from the original on November 18, 2023. Retrieved January 12, 2024.{{cite journal}}: CS1 maint: DOI inactive as of July 2025 (link)
  3. ↑ Gillette, David D.; Wolberg, Donald L.; Hunt, Adrian P. (1986). "Tyrannosaurus rex from the McRae Formation (Lancian, Upper Cretaceous), Elephant Butte reservoir, Sierra County, New Mexico" (PDF). New Mexico Geological Society Guidebook. 37: 235–238. doi:10.56577/FFC-37.235 (inactive July 12, 2025). S2CID 251985284. Archived (PDF) from the original on January 12, 2024. Retrieved January 12, 2024.{{cite journal}}: CS1 maint: DOI inactive as of July 2025 (link)
  4. ↑ Lehman, Thomas M.; Carpenter, Kenneth (1990). "A partial skeleton of the tyrannosaurid dinosaur Aublysodon from the Upper Cretaceous of New Mexico". Journal of Paleontology. 64 (6): 1026–1032. Bibcode:1990JPal...64.1026L. doi:10.1017/S0022336000019843. JSTOR 1305741. S2CID 132662000. Archived from the original on July 15, 2023. Retrieved March 17, 2024.
  5. ↑ Carr, Thomas D.; Williamson, Thomas E. (2000). "A review of Tyrannosauridae (Dinosauria: Coelurosauria) from New Mexico". Bulletin. 17. New Mexico Museum of Natural History and Science: 113–145.
  6. ↑ Sullivan, Robert M.; Lucas, Spencer G. (2015). "Cretaceous Vertebrates of New Mexico". New Mexico Museum of Natural History and Science Bulletin. 68.
  7. ↑ Schantz, E.; Amato, J.M.; Lawton, T.F. Dating dinosaurs in the Laramide foreland: U-Pb geochronologic constraints on a stratigraphic section containing Alamosaurus and the postulated Tyrannosaurus mcraeensis in the Love Ranch Basin. New Mexico Geological Society of America Abstracts with Programs. Vol. 56. p. 9.
  8. 1 2 Scherer, Charlie Roger (January 11, 2025). "Multiple lines of evidence support anagenesis in Daspletosaurus and cladogenesis in derived tyrannosaurines". Cretaceous Research. 169 106080. Bibcode:2025CrRes.16906080S. doi:10.1016/j.cretres.2025.106080. ISSN 0195-6671. Archived from the original on January 18, 2025. Retrieved January 17, 2025.
  9. ↑ Elbein, Asher (January 11, 2024). "New Origin Story for Tyrannosaurus Rex Suggested by Fossil - Researchers say the species they named Tyrannosaurus mcraeensis predated the dinosaur era's great predator". The New York Times. Retrieved January 12, 2024.{{cite news}}: CS1 maint: deprecated archival service (link)
  10. ↑ Morrison, C.; Scherer, C.R.; O'Callaghan, E.V.; Layton, C.; Boisvert, C.; Rolando, M.A.; Durrant, L.; Salas, P.; Allain, S.J.R.; Gascoigne, S.J.L. (2025). "Rise of the king: Gondwanan origins and evolution of megaraptoran dinosaurs". Royal Society Open Science. 12 (5) 242238. Bibcode:2025RSOS...1242238M. doi:10.1098/rsos.242238. PMC 12055284. PMID 40337259.
  11. ↑ Voris, Jared T.; Zelenitsky, Darla K.; Kobayashi, Yoshitsugu; Modesto, Sean P.; Therrien, François; Tsutsumi, Hiroki; Chinzorig, Tsogtbaatar; Tsogtbaatar, Khishigjav (June 11, 2025). "A new Mongolian tyrannosauroid and the evolution of Eutyrannosauria". Nature. 642 (8069): 973–979. Bibcode:2025Natur.642..973V. doi:10.1038/s41586-025-08964-6. ISSN 0028-0836. PMID 40500434. Supplementary Information Archived June 12, 2025, at the Wayback Machine
  12. ↑ Carr, Thomas D. (2025). "Observations on the skull of the type specimen of Tyrannosaurus rex Osborn, 1905". All Earth. 37 (1) 2539638: 1–66. doi:10.1080/27669645.2025.2539638.
  13. ↑ Paul, Gregory S.; Persons IV, W. Scott; van Raalte, Jay (2022). "The Tyrant Lizard King, Queen and Emperor: Multiple Lines of Morphological and Stratigraphic Evidence Support Subtle Evolution and Probable Speciation Within the North American Genus Tyrannosaurus". Evolutionary Biology. 49 (2): 156–179. Bibcode:2022EvBio..49..156P. doi:10.1007/s11692-022-09561-5. S2CID 247200214. Archived from the original on June 12, 2022. Retrieved March 1, 2022.
  14. 1 2 Elbein, Asher (February 28, 2022). "They Want to Break T. Rex Into 3 Species. Other Paleontologists Aren't Pleased". The New York Times. Archived from the original on March 1, 2022. Retrieved March 1, 2022.
  15. ↑ Hunt, Katie (March 1, 2022). "Tyrannosaurus rex may have been misunderstood". CNN. Archived from the original on March 4, 2022. Retrieved March 4, 2022.
  16. ↑ Greshko, Michael (March 1, 2022). "Call to split T. rex into 3 species sparks fierce debate". National Geographic. Archived from the original on March 1, 2022.
  17. ↑ Carr, T.D.; Napoli, J.G.; Brusatte, S.L.; Holtz, T.R.; Hone, D.W.E.; Williamson, T.E.; Zanno, L.E. (2022). "Insufficient Evidence for Multiple Species of Tyrannosaurus in the Latest Cretaceous of North America: A Comment on "The Tyrant Lizard King, Queen and Emperor: Multiple Lines of Morphological and Stratigraphic Evidence Support Subtle Evolution and Probable Speciation Within the North American Genus Tyrannosaurus"". Evolutionary Biology. 49 (3): 314–341. Bibcode:2022EvBio..49..327C. doi:10.1007/s11692-022-09573-1.
  18. ↑ Paul, Gregory S. (June 30, 2025). "A presentation of the current data on the exceptionally diverse non-tyrannosaurid eutyrannosaur and Tyrannosaurini genera and species of western North America during the End Cretaceous North American Interchange". Mesozoic. 2 (2): 085–138. doi:10.11646/mesozoic.2.2.1. ISSN 3021-1867.
  19. ↑ Cite error: The named reference paul1988 was invoked but never defined (see the help page).
  20. ↑ Olshevsky, G.; Ford, T.L.; Yamamoto, S. (1995). "The origin and evolution of the tyrannosaurids". Kyoryugaku Saizensen [Dino Frontline]. 9–10: 92–119.
  21. ↑ Carr, T. D.; Williamson, T. E. (2004). "Diversity of late Maastrichtian Tyrannosauridae (Dinosauria: Theropoda) from western North America". Zoological Journal of the Linnean Society. 142 (4): 479–523. doi:10.1111/j.1096-3642.2004.00130.x.
  22. ↑ Gilmore, C. W. (1946). "A new carnivorous dinosaur from the Lance Formation of Montana". Smithsonian Miscellaneous Collections. 106: 1–19.
  23. ↑ Bakker, R.T.; Williams, M.; Currie, P.J. (1988). "Nanotyrannus, a new genus of pygmy tyrannosaur, from the latest Cretaceous of Montana". Hunteria. 1: 1–30.
  24. ↑ Carr, T.D. (1999). "Craniofacial ontogeny in Tyrannosauridae (Dinosauria, Coelurosauria)". Journal of Vertebrate Paleontology. 19 (3): 497–520. Bibcode:1999JVPal..19..497C. doi:10.1080/02724634.1999.10011161. S2CID 83744433. Archived from the original on February 20, 2020. Retrieved December 6, 2019.
  25. ↑ Tsuihiji, T.; Watabe, M.; Tsogtbaatar, K.; Tsubamoto, T.; Barsbold, R.; Suzuki, S.; Lee, A.H.; Ridgely, R.C.; Kawahara, Y.; Witmer, L.M. (2011). "Cranial osteology of a juvenile specimen of Tarbosaurus bataar from the Nemegt Formation (Upper Cretaceous) of Bugin Tsav, Mongolia". Journal of Vertebrate Paleontology. 31 (3): 497–517. Bibcode:2011JVPal..31..497T. doi:10.1080/02724634.2011.557116. S2CID 15369707.
  26. ↑ Currie, P.J. (2003a). "Cranial anatomy of tyrannosaurid dinosaurs from the Late Cretaceous of Alberta, Canada". Acta Palaeontologica Polonica. 48: 191–226.
  27. ↑ Currie, Henderson, Horner and Williams (2005). "On tyrannosaur teeth, tooth positions and the taxonomic status of Nanotyrannus lancensis." In "The origin, systematics, and paleobiology of Tyrannosauridae", a symposium hosted jointly by Burpee Museum of Natural History and Northern Illinois University.
  28. ↑ Henderson (2005). "Nano No More: The death of the pygmy tyrant." In "The origin, systematics, and paleobiology of Tyrannosauridae", a symposium hosted jointly by Burpee Museum of Natural History and Northern Illinois University.
  29. ↑ Larson, P. (2013). The validity of Nanotyrannus lancensis (Theropoda, Lancian - Upper Maastrichtian of North America (PDF). Society of Vertebrate Paleontology 73rd Annual Meeting. p. 159. Archived (PDF) from the original on March 3, 2022. Retrieved October 31, 2025.
  30. ↑ Larson, P.L. (2013). "The case for Nanotyrannus". In Parrish, J.M.; Molnar, R.A.; Currie, P.J.; Koppelhus, E.B. (eds.). Tyrannosaurid Paleobiology. University of Indiana Press. pp. 15–53. ISBN 978-0253009302.
  31. ↑ Black, R. (November 10, 2011). ""Montana's "Dueling Dinosaurs"". smithsonianmag.com. Archived from the original on July 14, 2025. Retrieved October 30, 2025.
  32. ↑ Cornwall, W. (May 22, 2020). "Court rules 'Dueling Dinos' belong to landowners, in a win for science". science.org. Archived from the original on April 5, 2025. Retrieved October 30, 2025.
  33. ↑ Pishney, Jon (November 17, 2020). "North Carolina Museum of Natural Sciences to receive the "Dueling Dinosaurs"". Archived from the original on November 18, 2020. Retrieved October 31, 2025.
  34. ↑ Pishney, Jon (October 31, 2023). "Dueling Dinosaurs move into the SECU DinoLab | Programs and Events Calendar". Archived from the original on June 19, 2024. Retrieved October 31, 2025.
  35. ↑ Zanno, Lindsay E.; Napoli, James G. (October 30, 2025). "Nanotyrannus and Tyrannosaurus coexisted at the close of the Cretaceous". Nature. doi:10.1038/s41586-025-09801-6. ISSN 0028-0836.
  36. ↑ Maleev, E. A. (1955). "(title in Russian)" [Gigantic carnivorous dinosaurs of Mongolia] (PDF). Doklady Akademii Nauk SSSR (in Russian). 104 (4). translated by F. J. Alcock: 634–637. Archived (PDF) from the original on December 11, 2019. Retrieved April 30, 2013.
  37. ↑ Rozhdestvensky, A. K. (1965). "Growth changes in Asian dinosaurs and some problems of their taxonomy". Paleontological Journal. 3: 95–109.
  38. ↑ Cite error: The named reference holtz1994 was invoked but never defined (see the help page).
  39. ↑ Carpenter, K. (1992). "Tyrannosaurids (Dinosauria) of Asia and North America". In Mateer, N. J.; Chen, P.-j. (eds.). Aspects of nonmarine Cretaceous geology. Beijing: China Ocean Press. pp. 250–268. ISBN 978-7-5027-1463-5. OCLC 28260578.
  40. ↑ Cite error: The named reference carr2017 was invoked but never defined (see the help page).
  41. ↑ Hurum, J.H., Sabath, K. (2003). "Giant theropod dinosaurs from Asia and North America: Skulls of Tarbosaurus bataar and Tyrannosaurus rex compared" (PDF). Acta Palaeontologica Polonica. 48 (2): 161–190. Archived from the original (PDF) on May 17, 2023.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  42. 1 2 Li Feng, Bi Shundong, Michael Pittman, Stephen L. Brusatte, Xu Xing (2016). "A new tyrannosaurine specimen (Theropoda: Tyrannosauroidea) with insect borings from the Upper Cretaceous Honglishan Formation of Northwestern China". Cretaceous Research. 66: 155–162. Bibcode:2016CrRes..66..155L. doi:10.1016/j.cretres.2016.06.002. hdl:20.500.11820/a49b0878-3ba2-4c3e-b4b1-70fe282e43ea.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  43. 1 2 Sebastian G. Dalman, Spencer G. Lucas (January 2018). "Tyrannosaurid dinosaurs (Theropoda: Tyrannosauridae) from the Upper Cretaceous (Early Campanian) Allison Member of the Menefee Formation, New Mexico: Implications for the origin of Tyrannosauridae in North America". Fossil Record. New Mexico Museum of Natural History and Science Bulletin. 6 (79): 99–112.
  44. ↑ Cite error: The named reference holtz2004 was invoked but never defined (see the help page).
  45. ↑ A. O. Averianov, A. A. Yarkov (2004). "Carnivorous dinosaurs (Saurischia, Theropoda) from the Maastrichtian of the Volga-Don Interfluve, Russia" (PDF). Paleontological Journal. 38 (1): 78–82. Archived (PDF) from the original on March 5, 2024.
  46. ↑ A. O. Averianov, A. V. Lopatin (2023). "Динозавры России: обзор местонахождений [Dinosaurs of Russia: Overview of locations]" (PDF). Vestnik Rossiiskoi Akademii Nauk (in Russian). 93 (4): 342–354. doi:10.31857/S0869587323040023. Archived (PDF) from the original on February 16, 2024.
  47. ↑ Hone, D. W. E.; Wang, K.; Sullivan, C.; Zhao, X.; Chen, S.; Li, D.; Ji, S.; Ji, Q.; Xu, X. (2011). "A new, large tyrannosaurine theropod from the Upper Cretaceous of China". Cretaceous Research. 32 (4): 495–503. Bibcode:2011CrRes..32..495H. doi:10.1016/j.cretres.2011.03.005.
  48. ↑ Urban, Michael A.; Lamanna, Matthew C. (December 2006). "Evidence of a Giant Tyrannosaurid (Dinosauria: Theropoda) from the Upper Cretaceous (?Campanian) of Montana". Annals of Carnegie Museum. 75 (4): 231–235. doi:10.2992/0097-4463(2006)75[231:EOAGTD]2.0.CO;2. ISSN 0097-4463.
  49. ↑ Dalman, Sebastian G.; Lucas, Spencer G.; Malinzak, D. Edward (2018). "Tyrannosaurid teeth from the upper Cretaceous (Campanian) Two Medicine Formation of Montana". New Mexico Museum of Natural History and Science Bulletin. 79: 125–139.
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