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Qianzhousaurus

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Qianzhousaurus
Temporal range: Late Cretaceous,
~67–66 Ma
↓
Holotype skull cast at Japan
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: Theropoda
Family: †Tyrannosauridae
Subfamily: †Tyrannosaurinae
Clade: †Alioramini
Genus: †Qianzhousaurus
Lü et al., 2014
Type species
†Qianzhousaurus sinensis
Lü et al., 2014

Qianzhousaurus (meaning "Qianzhou lizard") is a genus of tyrannosaurid dinosaurs that lived in Asia during the Late Cretaceous period. There is currently only one species named, the type species Qianzhousaurus sinensis which is a member of the tribe Alioramini within the group, and most closely related to Alioramus, another alioramin.

History of discovery

Map showing the locality of the Ganzhou city, region where the holotype was discovered

The holotype specimen, GM F10004, was unearthed in southern China, Ganzhou, at the Nanxiong Formation in the summer of 2010 during the construction of an industrial park and it was first described by paleontologists Junchang Lü, Laiping Yi, Stephen L. Brusatte, Ling Yang, Hua Li and Liu Chen in the journal Nature Communications in 2014. The genus is known from a partial sub-adult individual consisting of a nearly complete skull with the lower jaws missing all teeth (lost during fossilization), 9 cervical vertebrae, 3 dorsal vertebrae, 18 caudal vertebrae, both scapulocoracoids, partial ilia, and the left hindlimb compromising the femur, tibia, fibula, astragalus with calcaneum, and metatarsals III and IV. The generic name, Qianzhousaurus, is in reference to Qianzhou (the older name of Ganzhou) where the remains were discovered, and the specific name, sinensis, is derived from the Greek Σῖναι (sin, sino, sinai) in reference to China.[1] The fossil remains were discovered by workmen at a construction site near the city of Ganzhou, who then took them to a local museum.[2]

Lead author Lü Junchang from the Institute of Geology, Chinese Academy of Geological Sciences stated that "the new discovery is very important. Along with Alioramus from Mongolia, it shows that the long-snouted tyrannosaurids were widely distributed in Asia. Although we are only starting to learn about them, the long-snouted tyrannosaurs were apparently one of the main groups of predatory dinosaurs in Asia."[3] The existence of long-snouted tyrannosaurs was previously suspected due to other inconclusive fossil finds which could be explained as the juveniles of short-snouted species, but co-author Stephen L. Brusatte from the University of Edinburgh reveals that the find "tells us pretty unequivocally that these long-snouted tyrannosaurs were a real thing. They were a different breed, living right at the end of the age of dinosaurs."[4]

Description

Life restoration

Qianzhousaurus was a medium-sized tyrannosaurid estimated at 6.3 m (21 ft) in length, 2 m (6.6 ft) in hip height and 750–757 kg (1,653–1,669 lb) in body mass.[1][5] Higher estimates show that it could reach a maximum length between 7.5 and 9 metres (25 and 30 ft).[6] The taxon can be differentiated from other tyrannosaurids in having a highly narrowed premaxilla, a pneumatic opening on the upper extension of the maxilla, and the lack of a vertical ridge-like structure on the lateral surface of the ilium.[1]

Unlike more "traditional" tyrannosaurids, which had prominent deep-set jaws and thick teeth, Qianzhousaurus had a particularly elongated snout, with (when restored) narrow teeth. The holotype specimen is notably larger and more mature than the holotypes of both species of Alioramus; however, given that some sutures between the cervical and dorsal vertebrae are partially fused, the holotype was an immature animal, likely a sub-adult. Qianzhousaurus was a long-legged animal with a 70 cm (28 in) long femur and 76 cm (30 in) long tibia.[1]

Classification

Holotype skull diagram of A. remotus, which together with A. altai form the closest relatives of Qianzhousaurus

The discovery of Qianzhousaurus led to a new branch of the tyrannosaur family being named, consisting of the long-snouted Q. sinensis and the two known species of Alioramus. This clade, named the tribe Alioramini, had an uncertain placement relative to other members of the tyrannosaur branch in the initial analysis that discovered it. The primary phylogenetic analysis found Alioramini to be closer to Tyrannosaurus than to Albertosaurus, and therefore a member of the group Tyrannosaurinae. However, a second analysis in the same paper found it to be located outside of the clade including Albertosaurinae and Tyrannosaurinae, and therefore the sister group of Tyrannosauridae. Below is the first analysis found by the authors:[1]

Tyrannosauridae

Thomas D. Carr with colleagues in 2017 regarded Qianzhousaurus as a junior synonym of Alioramus based on the reasoning that they were recovered as sister species in their phylogenetic analysis. Despite their argument, they indicated that this synonymy does not necessarily constitute a taxonomic reevaluation of the Alioramini.[7] However, Foster and his colleagues in 2022 conducted a detailed redescription of the holotype skull of Qianzhousaurus, finding several traits unique to this genus, hence supporting the separation of Alioramus and Qianzhousaurus.[8]

Paleobiology

Ontogeny

Qianzhousaurus (in blue) compared to other members of the Alioramini

A 2022 study of the three known species of the two known alioramin genera, Qianzhousaurus, Alioramus (A. altai and A. remotus) respectively, suggests that the variation seen between the various species is consistent with the growth trends seen in other tyrannosaurid genera, though specimens that could constitute a full growth series from infant to adult for each species have not been recovered for any of these theropods. Of these, Qianzhousaurus represents the largest and most mature animal found within Alioramini thus far and represents the adult level of maturity. One part of the growth series across all specimens in this study was discovered to remain unique to alioramin tyrannosaurs; the rugose process of the jugal starts small and conical, but becomes massive and indistinct as the animals grow. This same study also suggests Alioramins did not undergo a secondary metamorphosis from slender juveniles to robust adults like other tyrannosaurs but maintained a unique physiology better suited to pursuit of fast prey.[8]

Feeding

Foster and his colleagues in 2022 indicated that Qianzhousaurus and other alioramins, due to their slim and gracile build, may have been hunters of small, particularly fast and nimble prey, which would have allowed these tyrannosaurids to avoid competition with larger, robust relatives that specialized in killing larger animals. The long and delicate snouts of alioramins like Alioramus and Qianzhousaurus may have prevented them from killing the same prey that juvenile and adult tyrannosaurids like Tarbosaurus hunted, though these larger tyrannosaurs themselves may have hunted alioramins as prey on occasion. Alioramins may also have had a different feeding strategy than other tyrannosaurids, as their jaws seem to have been weaker than those of the larger genera, and even juveniles of larger species have proportionately higher bite forces than alioramins of equivalent size. Furthermore, Alioramins seemingly remained confined to Asia, suggesting some factor prevented them from colonizing the better-sampled fossil deposits from North America. What this may be remains a mystery at the present moment.[8]

Paleoenvironment

Qianzhousaurus is known from the Nanxiong Formation, which has been dated to the latest Maastrichtian stage of the Late Cretaceous epoch, about 66.7 ± 0.3 million years ago based on argon–argon dating.[9] The main lithology of this formation is composed by purplish mudstones and siltstones, and was deposited in a floodplain environment, under a relatively warm, humid subtropical climate.[10] Oviraptorid eggs are particularly common across the formation with numerous well-preserved egg clutches or nests,[11] as well as nesting individuals.[12][13][14] The Nanxiong Formation has been noted for its abundant oviraptorosaur genera. It is most likely that, given the poor stratigraphic analysis of the formation, the extremely large oviraptorosaur diversity of this formation was temporally separated.[15]

Other vertebrates in the Nanxiong Formation include numerous oviraptorosaurs, such as Banji, Ganzhousaurus, Corythoraptor, Nankangia, Huanansaurus, Shixinggia, or Tongtianlong;[15][16] hadrosaurid Microhadrosaurus (may be nomen dubium);[17] sauropod Gannansaurus;[18] therizinosaurid Nanshiungosaurus;[19] crocodilian Jiangxisuchus;[20] squamates Chianghsia and Tianyusaurus;[21] and turtles Jiangxichelys and Nanhsiungchelys.[10]

See also

References

  1. ^ a b c d e Lü, J.; Yi, L.; Brusatte, S. L.; Yang, L.; Chen, L. (2014). "A new clade of Asian Late Cretaceous long-snouted tyrannosaurids". Nature Communications. 5 (3788): 3788. Bibcode:2014NatCo...5.3788L. doi:10.1038/ncomms4788. PMID 24807588.
  2. ^ Dinosaurs (2014-05-07). "Long-nosed 'Pinocchio rex' dinosaur discovered by scientists". London: Telegraph. Archived from the original on 2014-05-08. Retrieved 2014-05-22.
  3. ^ "Qianzhousaurus sinensis: Long-Snouted Tyrannosaur Discovered in China | Paleontology". Sci-News.com. 2014-05-07. Retrieved 2014-05-22.
  4. ^ Jacqueline Howard (2014-05-07). "'Pinocchio Rex' Dinosaur Unearthed In China Confirms Theory About Tyrannosaurs". Huffingtonpost.com. Retrieved 2014-05-22.
  5. ^ Molina-Pérez, R.; Larramendi, A. (2016). Récords y curiosidades de los dinosaurios Terópodos y otros dinosauromorfos. Barcelona, Spain: Larousse. p. 266. ISBN 9788416641154.
  6. ^ Xing, L.; Niu, K.; Lockley, M.G.; Klein, H.; Romilio, A.; Persons, W.S.; Brusatte, S.L. (2019). "A probable tyrannosaurid track from the Upper Cretaceous of southern China". Science Bulletin. 64 (16): 1136–1139. doi:10.1016/j.scib.2019.06.013.
  7. ^ 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.
  8. ^ a b c Foster, William; Brusatte, Stephen L.; Carr, Thomas D.; Williamson, Thomas E.; Yi, Laiping; Lü, Junchang (11 February 2022). "The cranial anatomy of the long-snouted tyrannosaurid dinosaur Qianzhousaurus sinensis from the Upper Cretaceous of China". Journal of Vertebrate Paleontology: e1999251. doi:10.1080/02724634.2021.1999251. S2CID 246799243. Retrieved 23 February 2022 – via Taylor and Francis+NEJM.
  9. ^ 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.
  10. ^ a b Tong, H.; Li, L. (2019). "A revision of the holotype of Nanhsiungchelys wuchingensis, Ye, 1966 (Testudines: Cryptodira: Trionychoidae: Nanhsiungchelyidae)". Cretaceous Research. 95: 151−163. doi:10.1016/j.cretres.2018.11.003. hdl:311034/9424.
  11. ^ Yang, T.-R.; Wiemann, J.; Xu, L.; Cheng, Y.-N.; Wu, X.-C.; Sander, P. M. (2019). "Reconstruction of oviraptorid clutches illuminates their unique nesting biology". Acta Palaeontologica Polonica. 466: 581−596. doi:10.4202/app.00497.2018.
  12. ^ Sato, T.; Cheng, Y.-N.; Wu, X.-C.; Zelenitsky, D. K.; Hsiao, Y.-F. (2005). "A Pair of Shelled Eggs Inside A Female Dinosaur". Science. 308 (5720): 375. doi:10.1126/science.1110578. PMID 15831749. S2CID 19470371.
  13. ^ Jin, X.; Varricchio, D. J.; Poust, A. W.; He, T. (2020). "An oviraptorosaur adult-egg association from the Cretaceous of Jiangxi Province, China". Science. 39 (6): e1739060. doi:10.1080/02724634.2019.1739060. S2CID 219447073.
  14. ^ Bi, S.; Amiot, R.; Peyre de Fabrègues, C.; Pittman, M.; Lamanna, M. C.; Yu, Y.; Yu, C.; Yang, T.; Zhang, S.; Zhao, Q.; Xu, X. (2021). "An oviraptorid preserved atop an embryo-bearing egg clutch sheds light on the reproductive biology of non-avialan theropod dinosaurs". Science Bulletin. 66 (9): 947–954. doi:10.1016/j.scib.2020.12.018.
  15. ^ a b 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): 35780. Bibcode:2016NatSR...635780L. doi:10.1038/srep35780. PMC 5103654. PMID 27831542.
  16. ^ 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.
  17. ^ Xing, L.; Lockley, M. G.; Li, D.; Klein, H.; Ye, Y.; Scott Persons IV, W.; Ran, H. (2017). "Late Cretaceous ornithopod-dominated, theropod, and pterosaur track assemblages from the Nanxiong Basin, China: New discoveries, ichnotaxonomy, and paleoecology" (PDF). Palaeogeography, Palaeoclimatology, Palaeoecology. 466: 303−313. Bibcode:2017PPP...466..303X. doi:10.1016/j.palaeo.2016.11.035.
  18. ^ Lü, J.; Yi, L.; Zhong, H.; Wei, X. (2013). "A New Somphospondylan Sauropod (Dinosauria, Titanosauriformes) from the Late Cretaceous of Ganzhou, Jiangxi Province of Southern China". Acta Geologica Sinica (English Edition). 87 (3): 678−685. doi:10.1111/1755-6724.12079.
  19. ^ Zanno, L. E. (2010). "A taxonomic and phylogenetic re-evaluation of Therizinosauria (Dinosauria: Maniraptora)". Journal of Systematic Palaeontology. 8 (4): 503−543. doi:10.1080/14772019.2010.488045. S2CID 53405097.
  20. ^ Chun Li; Xiao-chun Wu; Scott Rufolo (2018). "A new crocodyloid (Eusuchia: Crocodylia) from the Upper Cretaceous of China". Cretaceous Research. 94: 25–39. doi:10.1016/j.cretres.2018.09.015.
  21. ^ 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. doi:10.1080/14772019.2011.588254. S2CID 85682211.
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