''Shuangmiaosaurus'' 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 ...

of herbivorous

ornithischian Ornithischia () is an extinct order of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name ''Ornithischia'', or "bird-hipped", reflects this similarity and is derived from the Greek ...

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 ...

which lived during the late

Albian The Albian is both an age of the geologic timescale and a stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early/Lower Cretaceous Epoch/ Series. Its approximate time range is 113.0 ± 1.0 Ma to 100.5 ± ...

age of the Early

Cretaceous Period 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 ...

, about 100 million years ago.Carpenter, K. and Ishida, Y. (2010).
Early and “Middle” Cretaceous Iguanodonts in Time and Space.
''

Journal of Iberian Geology ''Journal of Iberian Geology'' (formerly ''Cuadernos de Geología Ibérica'') is a triannual peer-reviewed scientific journal published by the Universidad Complutense de Madrid. The journal covers the field of geology and related earth science ...

'', 36 (2): 145-164 It was an iguanodont euornithopod which lived in China. The

type species In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen( ...

, ''Shuangmiaosaurus gilmorei'', was named and described by

You Hailu In Modern English, ''you'' is the second-person pronoun. It is grammatically plural, and was historically used only for the dative case, but in most modern dialects is used for all cases and numbers. History ''You'' comes from the Proto- ...

Ji Qiang Ji or JI may refer to: Names and titles * Ji (surname), the pinyin romanization of a number of distinct Chinese surnames * Ji (Korean name), a Korean surname and element in given names (including lists of people with the name) * -ji, an honorific ...

Li Jinglu and Li Yinxian in 2003. The generic name refers to the village of Shuangmiao in

Beipiao Beipiao () is a city in Chaoyang prefecture, Liaoning province, in Northeast China. It has a population of 202,807. The main industry in the area is coal mining. With vertical shafts of almost 1000m, these are some of the deepest coal mines in ...

in Liaoning Province, the site of the discovery. The specific name honours the American

paleontologist Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of foss ...

Charles Whitney Gilmore Charles Whitney Gilmore (March 11, 1874 – September 27, 1945) was an American paleontologist who gained renown in the early 20th century for his work on vertebrate fossils during his career at the United States National Museum (now the N ...

. 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 ...

, specimen LPM 0165, was found in the

Sunjiawan Formation The Sunjiawan Formation () is a geological formation in Liaoning, China, with strata possibly dating back to the early Late Cretaceous, specifically the Cenomanian.Xi et al., 2018 Dinosaur remains are among the fossils that have been recovered fro ...

, originally seen as dating to the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', ...

( Cenomanian to

Turonian The Turonian is, in the ICS' geologic timescale, the second age in the Late Cretaceous Epoch, or a stage in the Upper Cretaceous Series. It spans the time between 93.9 ± 0.8 Ma and 89.8 ± 1 Ma (million years ago). The Turonian is preceded ...

) but today considered to have been somewhat older. It consists of a partial left upper jaw and lower jaw, including the

maxilla The maxilla (plural: ''maxillae'' ) in vertebrates is the upper fixed (not fixed in Neopterygii) bone of the jaw formed from the fusion of two maxillary bones. In humans, the upper jaw includes the hard palate in the front of the mouth. The ...

, part of the praemaxilla, elements of the lacrimal and 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 ...

. ''Shuangmiaosaurus'' was a rather large euornithopod. In 2010

Gregory S. Paul Gregory Scott Paul (born December 24, 1954) is an American freelance researcher, author and illustrator who works in paleontology, and more recently has examined sociology and theology. He is best known for his work and research on theropod dino ...

estimated its length at 7.5 metres, its weight at 2.5 tonnes. ''Shuangmiaosaurus'' was originally considered a

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 ...

member of the

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, Euro ...

, one closely related to the

Hadrosauridae Hadrosaurids (), or duck-billed dinosaurs, are members of the ornithischian family Hadrosauridae. This group is known as the duck-billed dinosaurs for the flat duck-bill appearance of the bones in their snouts. The ornithopod family, which incl ...

. Subsequent authors, including

David B. Norman David Bruce Norman (born 20 June 1952 in the United Kingdom) is a British paleontologist, currently the main curator of vertebrate paleontology at the Sedgwick Museum, Cambridge University. From 1991 to 2011, Norman has also been the Sedgwick Mus ...

Cambridge University , mottoeng = Literal: From here, light and sacred draughts. Non literal: From this place, we gain enlightenment and precious knowledge. , established = , other_name = The Chancellor, Masters and Schola ...

, consider it a more basal member of the

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- ...

outside of the Hadrosauroidea.Norman, D.B. (2004). "Basal Iguanodontia." In D. B. Weishampel, P. Dodson, and H. Osmólska (eds.), ''The Dinosauria'' (2nd edition). University of California Press, Berkeley 413-437

References

Iguanodonts Early Cretaceous dinosaurs of Asia Fossil taxa described in 2003 Paleontology in Liaoning Ornithischian genera {{ornithopod-stub