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| Tongnanlong zhimingi X. Wei, Tan, Jiang, Ding, L. Li, Wang, Y.-y. Liu, G. Wei, D. Li, Y. Liu, Peng, Zhang & Lao, 2025 |
Abstract
The Sichuan Basin has yielded abundant sauropod dinosaurs from the Middle-Late Jurassic, and Mamenchisauridae had predominated the dinosaur faunae during the Late Jurassic in the Sichuan Basin. Here, we describe a new sauropod dinosaur, Tongnanlong zhimingi gen. et sp. nov. from the Upper Jurassic Suining Formation in the Sichuan Basin, southwestern China. The holotype includes three dorsal and six caudal vertebrae, scapula, coracoid, and some hindlimb bones. It is diagnosed by the complex structures of the dorsal and anterior caudal vertebrae compared to other mamenchisaurids. Phylogenetic analysis shows that it is more closely related to Mamenchisaurus than to Omeisaurus. The huge-sized scapula and coracoid also indicate that the specimen belongs to an extremely gigantic individual with a body length approaching about 25 ~ 26 m. The new specimen enriches the diversity of Mamenchisauridae and provides additional information for understanding the evolution and diversity of eusauropod dinosaurs.
Keywords: Sauropoda, Mamenchisauridae, Upper Jurassic, Suining Formation, Phylogeny
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| Fossil remains of Tongnanlong zhimingi (TNM 0254). (A) Skeletal outlines showing recovered elements in blue color. The skeletal reconstruction is the proportional scaling of Mamenchisaurus youngi with copyright Scott Hartman (2022) (www.skeletaldrawing.com); (B1-B3) Dorsal vertebrae in lateral view; (B4) dorsal neural spine in posterior view; (C1-C5) Caudal vertebrae in lateral view; (C6) caudal neural spine in lateral view; (C7) chevron in lateral-posterior view; (D) Scapula and coracoid in lateral view; (E) Fibula in anterior view; (F1-F3) Metatarsals in dorsal view; (G1, G2) Claws in lateral view. |
Systematic paleontology
Saurischia
Sauropodomorpha
Sauropoda
Eusauropoda
Mamenchisauridae
Tongnanlong zhimingi gen. et sp. nov.
Etymology. The generic name Tongnan, Chinese Pinyin, refers to the Tongnan District, where the holotype was found; the word ‘long’ in Chinese Pinyin for dragon. The specific name is in honor of the world-famous dinosaur scientist Mr. Dong Zhiming for his great contributions to the dinosaur research in the Sichuan Basin.
Holotype. An incomplete individual that includes three dorsal and six caudal vertebrae, left shoulder girdle (scapula and coracoid) and hindlimb elements (partial tibia, fibula, three metatarsals, and two unguals). The specimen is housed in Tongnan Museum, with the specimen number of TNM 0254.
Type locality and horizon. The building site of Dafo Street (with GPS N30°10’44”, E105°48’17”), Tongnan District; Upper Jurassic, Suining Formation.
Diagnosis. A huge-bodied mamenchisaurid dinosaur with the following unique combination of characters: dorsal centra opisthocoelous, camerate pneumatic structures of dorsal centra, well-deveolped spinopostzygapophysial lamina of dorsal vertebrae, anterior caudal centra procoelous, neural spine of anterior caudal vertebrae oriented posterodorsally, small lamina within the pleurocoels on dorsal centra, neural spine of the dorsal vertebrae and postozygapophyses forming laminae and fossae, fossa developed between the postzygapopaphysis and hyposphene on anterior caudal vertebra, S-shaped suture of scapula and coracoid, obtuse angle of the scapular and coracoid articular surfaces of glenoid, coracoid fossa much close to the scapular margin than to the glenoid margin, scapular acromion weakly developed and bearing no hook-like process.
Xuefang Wei, Yuanjun Tan, Shan Jiang, Jun Ding, Lei Li, Xiaobing Wang, Yiyang Liu, Guangbiao Wei, Deliang Li, Yu Liu, Guangzhao Peng, Shizhen Zhang and Changling Lao. 2025. A new mamenchisaurid from the Upper Jurassic Suining Formation of the Sichuan Basin in China and its implication on sauropod gigantism. Scientific Reports. 15, 24808. DOI: doi.org/10.1038/s41598-025-09796-0 [10 July 2025]
