''Bolong'' (meaning "Bo's dragon") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial n ...

iguanodontia Iguanodontia (the iguanodonts) is a clade of herbivorous dinosaurs that lived from the Middle Jurassic to Late Cretaceous. Some members include ''Camptosaurus'', '' Dryosaurus'', '' Iguanodon'', '' Tenontosaurus'', and the hadrosaurids or "duck- ...

dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is t ...

known from the

Early Cretaceous The Early Cretaceous (geochronological name) or the Lower Cretaceous ( chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pr ...

-age

Yixian Formation The Yixian Formation (; formerly transcribed as Yihsien Formation) is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans the late Barremian and early Aptian stages of the Early Cretaceous. It is known for its ...

of western

Liaoning Province Liaoning () is a coastal province in Northeast China that is the smallest, southernmost, and most populous province in the region. With its capital at Shenyang, it is located on the northern shore of the Yellow Sea, and is the northernmost ...

, China. It lived about 125 million years ago in the earliest

Aptian The Aptian is an age in the geologic timescale or a stage in the stratigraphic column. It is a subdivision of the Early or Lower Cretaceous Epoch or Series and encompasses the time from 121.4 ± 1.0 Ma to 113.0 ± 1.0 Ma (million years ag ...

Discovery and naming

It was named by Wu Wen-hao, Pascal Godefroit and Hu Dong-yu in

2010 File:2010 Events Collage New.png, From top left, clockwise: The 2010 Chile earthquake was one of the strongest recorded in history; The Eruption of Eyjafjallajökull in Iceland disrupts air travel in Europe; A scene from the opening ceremony of ...

. The type species is ''Bolong yixianensis''. The genus name is derived from the names of the brothers Bo Hai-chen and Bo Xue, who helped uncover it, and the Mandarin word 龍 ''lóng'' "dragon". The specific epithet refers to the

where it was found. The

holotype A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of seve ...

fossil, YHZ-001, consists of a highly compressed

skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, t ...

with lower jaws from which a middle portion is missing. In 2013 a second specimen (ZMNH-M8812) was described consisting of an almost complete skeleton of a very young animal. It was found by a farmer near the village of Xitaizhi in

Inner Mongolia Inner Mongolia, officially the Inner Mongolia Autonomous Region, is an autonomous region of the People's Republic of China. Its border includes most of the length of China's border with the country of Mongolia. Inner Mongolia also accounts for ...

Description

''Bolong'' was a relatively small animal with an estimated length of four meters and a weight of 200 kilograms. The head is convex and fairly stocky with powerful mandibles. The teeth are relatively large.

Autapomorphies In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...

that have been established are a cavity at the interface of the lacrimal bone, the maxilla, the backwards branch of the prefrontal bone, consisting of a front-to-rear depth cavity above the edges of the eye socket, the lower protrusion of the predentarium extending rearwardly parallel to the lower edge, the interface of the predentarium that occupies less than two-thirds of the height of the dentarium so that the front tip of the dentarium protrudes a third above the predentarium, and that the teeth in the maxilla have dental crowns of which the main ridge bends at the tip of the tooth. A second autapomorpohy was identified based on the second specimen: the inside of the maxillary teeth are thickened and enclosed from the front and rear cutting edges and is divided in half by a striking vertical ledge.

Phylogeny

The describers placed ''Bolong'' in Hadrosauroidea. It would have been one of the most

basal Basal or basilar is a term meaning ''base'', ''bottom'', or ''minimum''. Science * Basal (anatomy), an anatomical term of location for features associated with the base of an organism or structure * Basal (medicine), a minimal level that is nec ...

hadrosauroids found in

Asia Asia (, ) is one of the world's most notable geographical regions, which is either considered a continent in its own right or a subcontinent of Eurasia, which shares the continental landmass of Afro-Eurasia with Africa. Asia covers an ...

References

Early Cretaceous dinosaurs of Asia Yixian fauna Iguanodonts Fossil taxa described in 2010 Taxa named by Pascal Godefroit Ornithischian genera {{ornithopod-stub