''Jinzhousaurus'' 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 nom ...

hadrosauroid Hadrosauroidea is a clade or superfamily of ornithischian dinosaurs that includes the "duck-billed" dinosaurs, or hadrosaurids, and all dinosaurs more closely related to them than to ''Iguanodon''. Their remains have been recovered in Asia, Eu ...

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 ...

of the Early Cretaceous of China. The type species is ''Jinzhousaurus yangi''. The generic name refers to the town

Jinzhou Jinzhou (, ), formerly Chinchow, is a coastal prefecture-level city in central-west Liaoning province, China. It is a geographically strategic city located in the Liaoxi Corridor, which connects most of the land transports between North Chin ...

. The specific name honours

Yang Zhongjian Yang Zhongjian, also Yang Chung-chien (; 1 June 1897 – 15 January 1979), courtesy name Keqiang (), also known as C.C. (Chung Chien) Young, was a Chinese paleontologist and zoologist. He was one of China's foremost vertebrate paleontologists. H ...

as the founder of Chinese paleontology. It was first described by Wang Xiao-lin and Xu Xing in 2001.

Discovery

Its

fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...

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 sever ...

IVPP V12691, was found near Baicaigou in Yixian County in the Dawangzhangzi Beds of the

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 exq ...

in Liaoning, China, having an oldest determinable age of 122 million years, during the early Aptian stage of the early

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of ...

Period.Zhou, Z. (2006). "Evolutionary radiation of the Jehol Biota: chronological and ecological perspectives." ''Geological Journal'', 41: 377-393. It consists of a nearly complete skeleton, compressed on a slab.

Description

''Jinzhousaurus'' has a length of about 7 metres (23 ft) and its skull is about half a metre long. Its snout was elongated with large nares and lacking an

antorbital fenestra An antorbital fenestra (plural: fenestrae) is an opening in the skull that is in front of the eye sockets. This skull character is largely associated with archosauriforms, first appearing during the Triassic Period. Among extant archosaurs, bird ...

. The back of the skull was uncommonly wide with a small crest on top. The

dentary In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

of the lower jaw has at least seventeen tooth positions.

Classification

''Jinzhousaurus'' shows a mix of basal and derived features. Originally assigned to (an already understood to be paraphyletic)

Iguanodontidae Iguanodontidae is a family of iguanodontians belonging to Styracosterna, a derived clade within Ankylopollexia. Characterized by their elongated maxillae, they were herbivorous and typically large in size. This family exhibited locomotive dynam ...

, later authors have referred it to the more general Iguanodontoidea. In 2010 a study concluded it was within this group a basal member of the more derived,

Hadrosauroidea Hadrosauroidea is a clade or superfamily of ornithischian dinosaurs that includes the "duck-billed" dinosaurs, or hadrosaurids, and all dinosaurs more closely related to them than to ''Iguanodon''. Their remains have been recovered in Asia, Europ ...

.A.T. McDonald, D. G. Wolfe, and J. I. Kirkland, 2010, "A new basal hadrosauroid (Dinosauria: Ornithopoda) from the Turonian of New Mexico", ''Journal of Vertebrate Paleontology'' 30(3): 799-812

References

External links

''Jinzhousaurus'' in The Natural History Museum's Dino Directory
Iguanodonts Early Cretaceous dinosaurs of Asia Aptian life Cretaceous China Fossils of China Yixian fauna Fossil taxa described in 2001 Taxa named by Xu Xing Ornithischian genera {{ornithopod-stub