Rhomaleopakhus
| Rhomaleopakhus Temporal range: Late Jurassic
| |
|---|---|
Scientific classification 
| |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Reptilia |
| Clade: | Dinosauria |
| Clade: | Saurischia |
| Clade: | †Sauropodomorpha |
| Clade: | †Sauropoda |
| Family: | †Mamenchisauridae |
| Genus: | †Rhomaleopakhus Upchurch et al., 2021 |
| Species: | †R. turpanensis
|
| Binomial name | |
| †Rhomaleopakhus turpanensis Upchurch et al., 2021
| |
Rhomaleopakhus (meaning "strong forearm") is a genus of mamenchisaurid sauropod, dinosaur from the Late Jurassic Kalaza Formation of China. The type and only species is Rhomaleopakhus turpanensis.[1]
Discovery and naming
[edit]The Rhomaleopakhus holotype specimen, IVPP-V11121-1, was found by a Chinese-Japanese Chunichi Shinibun expedition near Qiketai in Shanshan, Xinjiang province in 1993. It consists of a partial forelimb, comprising a humerus, ulna, radius, one carpal, and a partial manus. These bones were originally assigned to the coeval mamenchisaurid Hudiesaurus, which was found nearby.[2]. In 2004, Paul Upchurch rejected this identity because of a lack of overlapping material.[3]
In a 2021 reassessment of Hudiesaurus published by Upchurch and colleagues, the forelimb material was formally separated from this taxon and described as a new genus and species of mamenchisaurids, named Rhomaleopakhus turpanensis. The generic name combines the Greek rhomaleos, meaning "robust" and "pakhus, meaning "forearm". The specific name refers to the Turpan Basin where the specimen was collected.[1]
Description
[edit]Being a mamenchisaurid sauropod, Rhomaleopakhus was likely a large, quadrupedal herbivore. The closely related Mamenchisaurus has been suggested to have been a low or medium browser with a horizontal neck posture.[4]
Upchurch et al. (2021) noted that the robustness of the forelimb, after which the taxon was named, convergently evolved in what are called the "core Mamenchisaurus-like taxa" (CMTs),[5] titanosaurs, and ceratopsids. They believe this correlates with a more flexed orientation of the forearm, an enhanced role of the forearm in feeding, and a more anterior shift in the center of mass. It is possible that CMTs and titanosaurs specialized in a feeding strategy that involved efficient locomotion between sparsely located food sources.[1]
Classification
[edit]Upchurch et al. (2021) used the dataset of Moore et al. (2020)[5] to determine the phylogenetic relationships of Rhomaleopakhus. They found it to be a mamenchisaurid as the sister taxon to Chuanjiesaurus, in a clade that also includes Analong. Their results are displayed in the cladogram below:[1]
| Mamenchisauridae |
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Paleoecology
[edit]Rhomaleopakhus is known from the lower section of the Kalaza Formation in China, one of several fossiliferous formations in the Turpan Basin and Junggar Basin. The Kalaza Formation is Late Jurassic in age, overlying the Middle Jurassic-aged Qigu and Shishugou Formations and underlying the Early Cretaceous-aged Tugulu Group.[6] The Kalaza Formation itself is composed of thick red sandstones in mudstones deposited in terrestrial or fluvial environments.[1] Its was warm and seasonally dry, though towards the Cretaceous it transitioned to arid or semi-arid,[7][8] during the Late Jurassic, with alluvial deltas running through the area.[9] Although suggested to be from the Qigu Formation,[10] The Rhomaleopakhus holotype is definitively known from the Kalaza Formation.[1]
Other dinosaurs known from this formation include the mamenchisaurid Hudiesaurus,[2] the dubious sauropod Chiayusaurus,[11][12] an indeterminate megalosaurid theropod,[13] and the dubious theropod Szechuanosaurus.[1][13]
References
[edit]- ^ a b c d e f g Upchurch P, Mannion PD, Xu X, Barrett PM (2021). "Re-assessment of the Late Jurassic eusauropod dinosaur Hudiesaurus sinojapanorum Dong, 1997, from the Turpan Basin, China, and the evolution of hyper-robust antebrachia in sauropods". Journal of Vertebrate Paleontology. 41 (4): e1994414. Bibcode:2021JVPal..41E4414U. doi:10.1080/02724634.2021.1994414. S2CID 245164168.
- ^ a b Dong, Z. (1997). "A gigantic sauropod (Hudiesaurus sinojapanorum gen. et sp. nov.) from the Turpan Basin, China." Pp. 102-110 in Dong, Z. (ed.), Sino-Japanese Silk Road Dinosaur Expedition. China Ocean Press, Beijing.
- ^ Upchurch, P.; Barrett, P.M.; Dodson, P.; 2004 "Sauropoda". In: Weishampel, D.B. and Dodson, P. and Osmolska, H., (eds.) The Dinosauria. p 259 - 322. University of California Press: Berkeley and Los Angeles
- ^ Christian, Andreas; Peng, Guangzhao; Sekiya, Toru; Ye, Yong; Wulf, Marco G.; Steuer, Thorsten (2013-10-30). "Biomechanical Reconstructions and Selective Advantages of Neck Poses and Feeding Strategies of Sauropods with the Example of Mamenchisaurus youngi". PLOS ONE. 8 (10): e71172. Bibcode:2013PLoSO...871172C. doi:10.1371/journal.pone.0071172. ISSN 1932-6203. PMC 3812961. PMID 24204557.
- ^ a b Moore, A.J.; Upchurch, P.; Barrett, P.M.; Clark, J.M.; Xing, X. (2020). "Osteology of Klamelisaurus gobiensis (Dinosauria, Eusauropoda) and the evolutionary history of Middle–Late Jurassic Chinese sauropods". Journal of Systematic Palaeontology. 18 (16): 1299–1393. Bibcode:2020JSPal..18.1299M. doi:10.1080/14772019.2020.1759706. S2CID 219749618.
- ^ Xing, Lida; Scott Persons, W.; Lautenschlager, Stephan; Wang, Donghao; Niu, Kecheng (2021-05-01). "The first record of an ornithomimosaur from the Lower Cretaceous Tugulu Group of the Junggar Basin, Xinjiang, China". Cretaceous Research. 121 104740. Bibcode:2021CrRes.12104740X. doi:10.1016/j.cretres.2020.104740. ISSN 0195-6671.
- ^ Ashraf, A. Rahman; Sun, Yuewu; Sun, Ge; Uhl, Dieter; Mosbrugger, Volker; Li, Jie; Herrmann, Mark (2010-09-01). "Triassic and Jurassic palaeoclimate development in the Junggar Basin, Xinjiang, Northwest China—a review and additional lithological data". Palaeobiodiversity and Palaeoenvironments. 90 (3): 187–201. Bibcode:2010PdPe...90..187A. doi:10.1007/s12549-010-0034-0. ISSN 1867-1608.
- ^ Jolivet, Marc; Bourquin, Sylvie; Heilbronn, Gloria; Robin, Cecile; Barrier, Laurie; Dabard, Marie-Pierre; Jia, Yingying; De Pelsmaeker, Elien; Fu, Bihong (2017). "The Upper Jurassic–Lower Cretaceous alluvial-fan deposits of the Kalaza Formation (Central Asia): tectonic pulse or increased aridity?". Geological Society, London, Special Publications. 427 (1): 491–521. Bibcode:2017GSLSP.427..491J. doi:10.1144/SP427.6. ISSN 0305-8719.
- ^ Eberth, David A.; Brinkman, Donald B.; Chen, Pei-Ji; Yuan, Feng-Tian; Wu, Shao-Zu; Li, Gang; Cheng, Xian-Shen (2001). "Sequence stratigraphy, paleoclimate patterns, and vertebrate fossil preservation in Jurassic-Cretaceous strata of the Junggar Basin, Xinjiang Autonomous Region, People's Republic of China". Canadian Journal of Earth Sciences. 38 (12): 1627–1644. Bibcode:2001CaJES..38.1627E. doi:10.1139/e01-067. ISSN 0008-4077.
- ^ Xing, Lida; Miyashita, Tetsuto; Zhang, Jianping; Li, Daqing; Ye, Yong; Sekiya, Toru; Wang, Fengping; Currie, Philip J. (2015-01-02). "A new sauropod dinosaur from the Late Jurassic of China and the diversity, distribution, and relationships of mamenchisaurids". Journal of Vertebrate Paleontology. 35 (1): e889701. Bibcode:2015JVPal..35E9701X. doi:10.1080/02724634.2014.889701. ISSN 0272-4634.
- ^ Maisch, Michael W.; Matzke, Andreas T. (2019-02-10). "First record of a eusauropod (Dinosauria: Sauropoda) from the Upper Jurassic Qigu-Formation (southern Junggar Basin, China), and a reconsideration of Late Jurassic sauropod diversity in Xinjiang". Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen. 291 (1): 109–117. Bibcode:2019NJGPA.291..109M. doi:10.1127/njgpa/2019/0792.
- ^ Bohlin, B (1953). "Reports from the Scientific Expedition to the NorthWestern Provinces of China Under Leadership of Dr. Sven Hedin. VI. Vertebrate Palaeontology 6: Fossil Reptiles from Mongolia and Kansu". Statens Etnografiska Museum, Stockholm. 6 (6): 113.
- ^ a b Dong, Zhiming (1992). Dinosaurian faunas of China. Germany: China Ocean Press. pp. 97–98. ISBN 3-540-52084-8.
