Hudiesaurus

Hudiesaurus; Temporal range: Ma PreꞒ Ꞓ O S D C P T J K Pg N ↓
	Size comparison and skeletal diagram showing the approximate placement of the known vertebra
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Chordata
Clade:	Dinosauria
Clade:	Saurischia
Clade:	†Sauropodomorpha
Clade:	†Sauropoda
Family:	†Mamenchisauridae
Genus:	†Hudiesaurus; Dong, 1997
Species:	†H. sinojapanorum
Binomial name
	†Hudiesaurus sinojapanorum; Dong, 1997

Hudiesaurus (meaning "butterfly lizard") is a herbivorous

sauropod genus of dinosaur from China. Its fossil remains were found in 1993 by a Chinese-Japanese expedition near Qiketai in Shanshan, Xinjiang province. The genus contains a single species, Hudiesaurus sinojapanorum, was named and described by Dong Zhiming in 1997. The generic name is derived from Mandarin hudie, meaning "butterfly," and refers to a flat butterfly-shaped process on the front base of the vertebral spine. The specific name refers to the members of the Sino-Japan Silk Road Dinosaur Expedition but can also be read as "central part" in Chinese, a pun on the Japanese Chunichi Shimbun (again "central part") press group, which financed the research.^[1]

Discovery

Hudiesaurus is known from only two incomplete specimens, uncovered within sediments in the

type specimen (IVPP V 11120) is represented only by a very large posterior cervical vertebra. A partial skeleton belonging to a smaller individual was found about 1 kilometre (0.62 mi) away from the holotype. This specimen, IVPP P. 11121, consisting of a nearly complete right front leg and teeth, was referred to Hudiesaurus by Dong.^[1] In 2004, Paul Upchurch rejected this proposal because of a lack of overlapping material.^[2] Upchurch et al. made the specimen the holotype of a new genus, Rhomaleopakhus, in 2021.^[3]

Description

Despite the fragmentary nature of the fossil material, Hudiesaurus is believed to have been very large, even for a sauropod, given the considerable length of the vertebral centrum of 55 centimetres (22 in). Its body length is estimated at 20–30 metres (66–98 ft).[4]^[1] In 2016, Gregory S. Paul estimated its length at 25 metres (82 ft) and its weight at 25 tonnes (28 short tons).^[5] In 2021, Upchurch et al. suggested that the vertebra may be cervical instead of thoracic, suggesting that the animal would be at 32 metres (105 ft) and 55 tonnes (61 short tons).^[3]

Classification

In the original description, Dong thought Hudiesaurus may have been related to Mamenchisaurus and accordingly placed it in the Mamenchisauridae. In 2004, Upchurch limited the precision to a more general Eusauropoda.^[2] In the 2021 description of Rhomaleopakhus, the relationships of Hudiesaurus were again revised. In their phylogenetic analysis, Upchurch et al. proposed that Hudiesaurus was a member of the Mamenchisauridae, as a sister taxon to two Mamenchisaurus species (M. youngi and a referred specimen of M. hochuanensis) and Xinjiagtitan, as well as a clade containing the holotype of M. hochuanensis and Klamelisaurus.^[3] Their cladogram is shown below:

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

^ ^a ^b ^c 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.
^ ^a ^b 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
^
S2CID 245164168
.

^ Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2010 Appendix.
^ Paul, Gregory S. (2016). The Princeton Field Guide to Dinosaurs 2nd Edition. New Jersey: Princeton University Press. p. 207.

External links

"How big was Hudiesaurus?" Sauropod Vertebra Picture of the Week, January 17, 2008

[dong1997-1] 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.

[Upchurch2004-2] 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

[Rhomaleopakhus-3] 
S2CID 245164168
.

[Holtz2008-4] Holtz, Thomas R. Jr. (2011) Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages, Winter 2010 Appendix.

[5] Paul, Gregory S. (2016). The Princeton Field Guide to Dinosaurs 2nd Edition. New Jersey: Princeton University Press. p. 207.

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