Jinchuanloong

Jinchuanloong Temporal range: Middle Jurassic, late Bathonian PreꞒ Ꞓ O S D C P T J K Pg N ↓
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Dinosauria
Clade:	Saurischia
Clade:	† Sauropodomorpha
Clade:	† Sauropoda
Clade:	† Eusauropoda
Genus:	† Jinchuanloong Li et al., 2025
Species:	†J. niedu
Binomial name
†Jinchuanloong niedu Li et al., 2025

Jinchuanloong (meaning "Jinchuan dragon") is an extinct genus of eusauropod sauropod dinosaurs from the Middle Jurassic Xinhe Formation of China. The genus contains a single species, Jinchuanloong niedu, known from a partial skeleton including a nearly complete skull.

Discovery and naming

Jinchuanlong type locality (white star)

The Jinchuanloong holotype specimen, JCMF 0132, was discovered as the result of fieldwork conducted in 2017 by Dr. Li Daqing in outcrops of the Xinhe Formation in the Jinchuan District, of Gansu Province in northwest China. The specimen consists of a well-preserved, nearly complete skull and mandible articulated with the first five cervical vertebrae (including the atlas - axis complex) and 29 of the posteriormost (toward the end) caudal vertebrae , some of which are preserved with associated haemal arches . In the approximately 5-metre (16 ft) gap between the neck and tail, there are preserved impressions of the pelvic girdle and sacral vertebrae . The first three preserved caudals preserve only the neural spine . The remaining vertebrae are all articulated, exposed in right lateral view. Unfortunately, the caudal vertebrae were not yet collected at the time of their description in 2025, so protective fences were installed around them in the outcrop they are embedded in. ^[1]

In 2025, Li et al. described Jinchuanloong niedu as a new genus and species of eusauropod dinosaurs based on these fossil remains. The generic name, Jinchuanloong, combines a reference to the type locality in Jinchuan District with the Mandarin Chinese word long, meaning "dragon". The specific name, niedu, combines the Mandarin words nie, meaning "nickel" and du, meaning "city", in reference to Jinchuan's well-known nickel resources. ^[1]

Description

Speculative life restoration

The holotype skull of Jinchuanloong measures 31 centimetres (12 in) long and 12.5 centimetres (4.9 in) tall. It generally resembles the skulls of related taxa such as Mamenchisaurus youngi . In comparison to this taxon and Shunosaurus , the skull of Jinchuanloong appears to have a broader snout in dorsal view, though this may be the result of taphonomic deformation. ^[1]

Jinchuanloong is known only from anteriormost (toward the front) and posteriormost (toward the back) parts of the skeleton, specifically the skull, the beginning of the neck, and the end of the tail. Based on the relative location of these preserved elements, Jinchuanloong is estimated to be 10 metres (33 ft) long. There is no fusion between the neural arch and neural spine or the cervical and first preserved caudal vertebrae, which implies the holotype belongs to an individual that was not skeletally mature. Furthermore, the intercentrum and neurapophyses of the atlas are unfused, and the pineal foramen is large, both raising the possibility that the holotype is a juvenile. ^[1]

Classification

Speculative life restorations of the more basal Jobaria (top) and a more derived turiasaur, Moabosaurus (bottom)

In their phylogenetic analysis, Li et al. (2025) recovered Jinchuanloong as a basal member of the sauropod clade Eusauropoda, outside of Neosauropoda (the group containing diplodocoids and macronarians). Their analysis placed it in a position diverging after a roughly coeval clade comprising Jobaria from Niger and Lapparentosaurus from Madagascar, ^{[2] [3]} but before the Turiasauria. These results are displayed in the cladogram below: ^[1]

Eusauropoda	Shunosaurus Omeisaurus Mamenchisauridae Jobaria Lapparentosaurus Jinchuanloong Turiasauria Neosauropoda Diplodocoidea Macronaria

Paleoenvironment

Plesiosaur teeth from the upper Xinhe Formation

Jinchuanloong was collected from the lower outcrops of the Xinhe Formation, a member of the Qingtujing Group, which dates to the late Bathonian age of the Middle Jurassic. The lower section of the formation is made up of yellow conglomerates, sandstone, and siltstone, which are interbedded with silty mudstone. Fossil plants and pollen are also preserved in the lower part. ^[1] The upper section has yielded turtle remains and teeth of an indeterminate plesiosaur, in what is assumed to be a freshwater depositional environment. ^[4]

References

1. Li, Ning; Zhang, Xiaoqin; Ren, Xinxin; Li, Daqing; You, Hailu (2025-05-23). "A new eusauropod (Dinosauria, Sauropodomorpha) from the Middle Jurassic of Gansu, China". Scientific Reports . 15 (1). doi: 10.1038/s41598-025-03210-5 . ISSN   2045-2322. PMC   12102329 . PMID   40410409.
2. Sereno, Paul C.; Beck, Allison L.; Dutheil, Didier B.; Larsson, Hans C. E.; Lyon, Gabrielle H.; Moussa, Bourahima; Sadleir, Rudyard W.; Sidor, Christian A.; Varricchio, David J.; Wilson, Gregory P.; Wilson, Jeffrey A. (1999-11-12). "Cretaceous Sauropods from the Sahara and the Uneven Rate of Skeletal Evolution Among Dinosaurs" (PDF). Science . 286 (5443): 1342–1347. doi:10.1126/science.286.5443.1342. ISSN   0036-8075. PMID   10558986.
3. Raveloson, Miky Lova Tantely; Clark, Neil D. L.; Rasoamiaramana, Armand H. (2019-11-27). "New Information on the Madagascan Middle Jurassic sauropod Lapparentosaurus madagascariensis". Geosciences. 9 (12): 498. Bibcode:2019Geosc...9..498R. doi: 10.3390/geosciences9120498 . ISSN   2076-3263.
4. Gao, Ting; Li, Da-Qing; Li, Long-Feng; Yang, Jing-Tao (2019-08-13). "The first record of freshwater plesiosaurian from the Middle Jurassic of Gansu, NW China, with its implications to the local palaeobiogeography". Journal of Palaeogeography. 8 (1): 27. Bibcode:2019JPalG...8...27G. doi: 10.1186/s42501-019-0043-5 . ISSN   2524-4507.