Rhomaleopakhus

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Rhomaleopakhus
Temporal range: Late Jurassic 145 Ma
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Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: Saurischia
Clade: †Sauropodomorpha
Clade: †Sauropoda
Family: †Mamenchisauridae
Genus: †Rhomaleopakhus
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]

History[]

The holotype IVPP-V11121-1, was found by a Chinese-Japanese Chunichi Shinibun expedition near in Shanshan, Xinjiang province in 1993, along with the holotype of Hudiesaurus,[2] and is a partially complete forelimb consisting of a humerus, ulna, radius, one carpal, and a partially complete manus that was originally assigned to the coeval mamenchisaurid Hudiesaurus.[2] in 2004 rejected the identity because of a lack of overlapping material.[3] However, in a 2021 reassessment of the latter genus, the forelimb was separated from its hypodigm and named the holotype of a new genus and species, Rhomaleopakhus turpanensis; the specific name refers to the Turpan Basin where the specimen was collected.[1]

Description[]

Upchurch et al. note that the robustness of the forelimb, after which the taxon was named, convergently evolved in what are called the "Core Mamenchisaurus-like taxa" (CMTs)[4] 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[]

Upchurch et al. used Moore et al. (2020)'s[4] phylogenetic analysis to determine the relationships of Rhomaleopakhus. They found it to be a mamenchisaurid sister to Chuanjiesaurus, in a clade that also includes Analong. Their cladogram is shown below:[1]

Mamenchisauridae
 

Tienshanosaurus

 
 
 

Omeisaurus junghsiensis

 
 
 

Wamweracaudia

 
 
 
 

"Mamenchisaurus" sinocanadorum

 
 

Qijianglong

 
 
 
 
 

Analong

 
 
 

Chuanjiesaurus

 
 

Rhomaleopakhus

 
 
 
 
 

Hudiesaurus

 
 

"Mamenchisaurus" hochuanensis (referred)

 
 

"Mamenchisaurus" youngi

 
 

Xinjiangtitan

 
 
 

"Mamenchisaurus" hochuanensis (holotype)

 
 
 

Shishugou cervicodorsals

 
 
 

Klamelisaurus

 
 

Phu Kradung taxon

 
 
 
 
 
 
 
 
 
 

References[]

  1. ^ a b c d 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. Online edition: e1994414. doi:10.1080/02724634.2021.1994414. S2CID 245164168.
  2. ^ 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.
  3. ^ 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
  4. ^ 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. doi:10.1080/14772019.2020.1759706. S2CID 219749618.
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