Bolong
From the names of the brothers Bo Hai-chen and Bo Xue (who helped uncover the specimen) + Mandarin lóng (龍) meaning 'dragon'; overall meaning 'Bo's dragon'.
Bolong is a genus of iguanodontian dinosaur known from the Early Cretaceous Yixian Formation of western Liaoning Province, China. It lived about 125 million years ago in the earliest Aptian.
Under dispute
Bolong yixianensis was described as a basal iguanodontoid (Wu and colleagues, 2010), and a later analysis by the describing authors recovered it as the basalmost hadrosauroid, next to a monophyletic Iguanodontidae (Wu and Godefroit, 2012). McDonald and colleagues (2017) recover it with Jinzhousaurus as a small basal hadrosauroid clade, whereas Norman (2015) places it in an iguanodontoid clade outside Hadrosauriformes.
Diagnosis
- A depressed pit at the junction between the maxilla and lachrymal, in the position corresponding to an antorbital fenestra (which is absent)
- Caudal ramus of prefrontal forming a rostrocaudally elongated depression above the orbital margin
- Ventral process of predentary running caudally parallel to the ventral margin of the predentary
- Rostrodorsal articular surface for the predentary occupying less than two-thirds of the height of the dentary, with the rostral tip of the dentary situated at the lower one-third of the bone height
- Primary ridge on maxillary tooth crowns deflected distally (posteriorly curved)
Species
Bolong yixianensis Wu et al., 2010
Type species
Named for the Yixian Formation where the holotype was found.
- Holotype
- YHZ-001 , Yizhou Fossil Museum
- Material
- A nearly complete fossil skeleton.
- Horizon
- Dawangzhangzi Member, Yixian Formation, Barremian, Early Cretaceous , 125.8–121.4 million years ago
- Locality
- Bataigou, Liaoning, China
Notable specimens
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ZMNH-M8812
Zhejiang Museum of Natural History ontogeny
An almost complete skeleton of a very young Bolong, documenting juvenile proportions with a proportionally longer forelimb. It also provided a second autapomorphy of the maxillary teeth. Found by a farmer near Xitaizhi, Inner Mongolia.
References
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Wu, W. H.; Godefroit, P.; Hu, D. Y. (2010). [Bolong yixianensis gen. et sp. nov.: a new iguanodontoid dinosaur from the Yixian Formation of western Liaoning, China]. Geology and Resources 19(2): 127-133.
Named Bolong as a basal iguanodontoid.
wu2010a - Zheng, W.; Jin, X.; Shibata, M.; Azuma, Y. (2013). An early juvenile specimen of Bolong yixianensis (Ornithopoda: Iguanodontia) from the Lower Cretaceous of Ningcheng County, Nei Mongol, China. Historical Biology 26(2): 236-251. doi:10.1080/08912963.2013.809347 zheng2013b
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Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.
Source of the hip height estimate, and the appearance features.
jones2026a -
Wu, W. H.; Godefroit, P. (2012). Anatomy and relationships of Bolong yixianensis, an Early Cretaceous iguanodontoid dinosaur from western Liaoning, China. Bernissart Dinosaurs and Early Cretaceous Terrestrial Ecosystems (Godefroit, P., ed.). Indiana University Press, Bloomington.
Recovers Bolong as the basalmost hadrosauroid. Gives the horizon as "Dakangpu Member (equivalent to the Dawangzhangzi Beds) of the middle part of Yixian Formation" (p. 296).
wu2012a -
McDonald, A. T.; Gates, T. A.; Zanno, L. E.; Makovicky, P. J. (2017). Anatomy, taphonomy, and phylogenetic implications of a new specimen of Eolambia caroljonesa (Dinosauria: Ornithopoda) from the Cedar Mountain Formation, Utah, USA. PLOS ONE 12(5). doi:10.1371/journal.pone.0176896
Recovered Bolong with Jinzhousaurus as a small basal hadrosauroid clade.
mcdonald2017a -
Norman, D. B. (2015). On the history, osteology, and systematic position of the Wealden (Hastings group) dinosaur Hypselospinus fittoni (Iguanodontia: Styracosterna). Zoological Journal of the Linnean Society 173: 92-189. doi:10.1111/zoj.12193
Placed Bolong in an iguanodontoid clade outside Hadrosauriformes.
norman2015a