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Asiatyrannus

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For the coelurosaur of a similar name, see Aviatyrannis.

Asiatyrannus
Temporal range: Late Cretaceous (Maastrichtian), ~66.7 Ma[1]
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Skeletal diagram and fossil elements of the Asiatyrannus holotype
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Tyrannosauridae
Subfamily: †Tyrannosaurinae
Genus: †Asiatyrannus
Zheng et al., 2024
Species:
†A. xui
Binomial name
†Asiatyrannus xui
Zheng et al., 2024

Asiatyrannus (meaning "Asian tyrant") is an extinct genus of tyrannosaurine theropod dinosaurs from the Late Cretaceous Nanxiong Formation of China. The genus contains a single species, A. xui, known from a single specimen consisting of a skull and partial postcranial skeleton. Asiatyrannus is notable for its deep-snouted skull and small body size, in contrast to the gracile snout and larger size of the contemporary Qianzhousaurus. It represents the southernmost record of an Asian tyrannosaurid.[2]

Discovery and naming

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The Asiatyrannus holotype specimen, ZMNH M30360, was discovered in September 2017 in sediments of the Nanxiong Formation near Shahe Town in Nankang District of Ganzhou City, Jiangxi Province, China. The specimen consists of most of an articulated skull in addition to disarticulated parts of the postcrania, comprising much of the right and left legs and several caudal vertebrae.[2]

In 2024, Zheng et al. described Asiatyrannus xui as a new genus and species of tyrannosaurid based on these fossil remains. The generic name, Asiatyrannus, combines "Asia", the continent of origin, with the Latinised Greek suffix "-tyrannus", meaning "tyrant" or "king". The specific name, xui, honors prominent dinosaur researcher Xu Xing and his contributions to paleontological research in China.[2]

Description

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Life reconstruction of Asiatyrannus
Holotype skull of Asiatyrannus

Asiatyrannus is a small-medium-sized tyrannosaur. Its nearly complete skull measures 47.5 centimetres (18.7 in) long, and it has an estimated body length of 3.5–4 metres (11–13 ft). In comparison, the mature skull of the closely related Nanuqsaurus from the Prince Creek Formation of North America is estimated at 60–70 centimetres (24–28 in).[3] Since Nanuqsaurus likely had a body size similar to Albertosaurus, Asiatyrannus may represent the only tyrannosaurine in this smaller size class.[4] The Asiatyrannus holotype is about half the length of the contemporary Qianzhousaurus. However, the holotype of Asiatyrannus did not belong to a skeletally mature individual, and as such, it would have been larger when fully grown. Nevertheless, it had probably passed through the life stages of most rapid growth, and other tyrannosaurines in similar growth stages are more than twice as large.[2]

Classification

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Using a modified version of the phylogenetic dataset of Carr et al. (2017),[5] Zheng et al. recovered Asiatyrannus as a derived tyrannosaurine member of the Tyrannosauridae, in a polytomy with the North American Nanuqsaurus. These results are displayed in the cladogram below:[2]

Tyrannosauridae

Paleoecology

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Asiatyrannus is known from the Nanxiong Formation, which dates to the end of the Maastrichtian age of the late Cretaceous period. Many other dinosaurs have been described from layers of the formation, including the fellow tyrannosaurid Qianzhousaurus.[2] Large teeth indicate the presence of a large, unnamed tyrannosaurid in the ecosystem.[6] Other theropods include therizinosaurids (Nanshiungosaurus)[7] and many oviraptorids (Banji, Corythoraptor, Ganzhousaurus, Huanansaurus, Jiangxisaurus, Nankangia, Shixinggia, and Tongtianlong).[8][9] The somphospondylan sauropods Gannansaurus and Jiangxititan are also known from the formation.[10] The formation's non-dinosaurian fauna includes crocodilians (Jiangxisuchus),[11] lizards (Chianghsia and Tianyusaurus),[12] and turtles (Jiangxichelys).[13]

The Mongolian Nemegt Formation contains a similar fauna, including the large tyrannosaurine Tarbosaurus, two species of the alioramin Alioramus, and smaller tyrannosauroids such as Bagaraatan.[14]

See also

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References

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  1. ^ Buck, B. J.; Hanson, A. D.; Hengst, R. A.; Shu-sheng, H. (2004). ""Tertiary Dinosaurs" in the Nanxiong Basin, Southern China, Are Reworked from the Cretaceous". The Journal of Geology. 112 (1): 111–118. Bibcode:2004JG....112..111B. doi:10.1086/379695. S2CID 12866840.
  2. ^ a b c d e f Zheng, Wenjie; Jin, Xingsheng; Xie, Junfang; Du, Tianming (2024-07-25). "The first deep-snouted tyrannosaur from Upper Cretaceous Ganzhou City of southeastern China". Scientific Reports. 14 (1): 16276. Bibcode:2024NatSR..1416276Z. doi:10.1038/s41598-024-66278-5. ISSN 2045-2322. PMC 11272791. PMID 39054316.
  3. ^ Fiorillo, A. R.; Tykoski, R. S. (2014). Dodson, Peter (ed.). "A Diminutive New Tyrannosaur from the Top of the World". PLoS ONE. 9 (3): e91287. Bibcode:2014PLoSO...991287F. doi:10.1371/journal.pone.0091287. PMC 3951350. PMID 24621577.
  4. ^ Druckenmiller, Patrick S.; Erickson, Gregory M.; Brinkman, Donald; Brown, Caleb M.; Eberle, Jaelyn J. (2021-06-24). "Nesting at extreme polar latitudes by non-avian dinosaurs". Current Biology. 31 (16): 3469–3478.e5. Bibcode:2021CBio...31E3469D. doi:10.1016/j.cub.2021.05.041. ISSN 0960-9822. PMID 34171301. We note that other Prince Creek Formation tyrannosaurid material in the UAMES collection do not support the assertion that Nanuqsaurus is a diminutive, small-bodied tyrannosaur. Rather, adult-sized teeth and isolated postcranial elements suggest an adult body size more closely comparable to other North American tyrannosaurid taxa, such as Albertosaurus sarcophagus.
  5. ^ Carr, Thomas D.; Varricchio, David J.; Sedlmayr, Jayc C.; Roberts, Eric M.; Moore, Jason R. (2017). "A new tyrannosaur with evidence for anagenesis and crocodile-like facial sensory system". Scientific Reports. 7: 44942. Bibcode:2017NatSR...744942C. doi:10.1038/srep44942. PMC 5372470. PMID 28358353.
  6. ^ Mo, J.-Y.; Xu, X. (2015). "Large theropod teeth from the Upper Cretaceous of Jiangxi, southern China" (PDF). Vertebrata PalAsiatica. 53 (1): 63–72.
  7. ^ Dong, Z. (1979). "Cretaceous dinosaur fossils in southern China" [Cretaceous dinosaurs of the Huanan (south China)]. In Institute of Vertebrate Paleontology and Paleoanthropology; Nanjing Institute of Paleontology (eds.). Mesozoic and Cenozoic Redbeds in Southern China (in Chinese). Beijing: Science Press. pp. 342–350. Translated paper
  8. ^ Lü, J.; Chen, R.; Brusatte, S.L.; Zhu, Y.; Shen, C. (2016). "A Late Cretaceous diversification of Asian oviraptorid dinosaurs: evidence from a new species preserved in an unusual posture". Scientific Reports. 6: 35780. Bibcode:2016NatSR...635780L. doi:10.1038/srep35780. PMC 5103654. PMID 27831542.
  9. ^ Lü, J.; Li, G.; Kundrát, M.; Lee, Y.-N.; Sun, Z.; Kobayashi, Y.; Shen, C.; Teng, F.; Liu, H. (2017). "High diversity of the Ganzhou Oviraptorid Fauna increased by a new cassowary-like crested species". Scientific Reports. 7 (6393): 6393. Bibcode:2017NatSR...7.6393L. doi:10.1038/s41598-017-05016-6. PMC 5532250. PMID 28751667.
  10. ^ Mo, Jin-You; Fu, Qiong-Yao; Yu, Yi-Lun; Xu, Xing (2023-09-21). "A New Titanosaurian Sauropod from the Upper Cretaceous of Jiangxi Province, Southern China". Historical Biology: 1–15. doi:10.1080/08912963.2023.2259413. ISSN 0891-2963.
  11. ^ Li, C.; Wu, X. C.; Rufolo, S. J. (2019). "A new crocodyloid (Eusuchia: Crocodylia) from the upper cretaceous of China". Cretaceous Research. 94: 25–39. Bibcode:2019CrRes..94...25L. doi:10.1016/j.cretres.2018.09.015. S2CID 133661294.
  12. ^ Mo, J. Y.; Xu, X.; Evans, S. E. (2012). "A large predatory lizard (Platynota, Squamata) from the Late Cretaceous of South China". Journal of Systematic Palaeontology. 10 (2): 333. Bibcode:2012JSPal..10..333M. doi:10.1080/14772019.2011.588254. S2CID 85682211.
  13. ^ Tong, Haiyan; Mo, Jinyou (2010). "Jiangxichelys, a new nanhsiungchelyid turtle from the Late Cretaceous of Ganzhou, Jiangxi Province, China". Geological Magazine. 147 (6): 981–986. Bibcode:2010GeoM..147..981T. doi:10.1017/S0016756810000671. S2CID 131484464. Archived from the original on 11 July 2011. Retrieved 14 January 2011.
  14. ^ Słowiak, Justyna; Brusatte, Stephen L; Szczygielski, Tomasz (2024-02-16). "Reassessment of the enigmatic Late Cretaceous theropod dinosaur, Bagaraatan ostromi". Zoological Journal of the Linnean Society. doi:10.1093/zoolinnean/zlad169. ISSN 0024-4082.
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