''Changmiania'' (from the Chinese "changmian", meaning "eternal sleep") is a

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

of basal

ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (), that started out as small, bipedal running grazers and grew in size and numbers until they became one of the most successful groups of herbivores in the Cretaceous world ...

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 ...

that lived in what is now

China China, officially the People's Republic of China (PRC), is a country in East Asia. It is the world's most populous country, with a population exceeding 1.4 billion, slightly ahead of India. China spans the equivalent of five time zones and ...

during 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 Pro ...

. It contains a single species, ''Changmiania liaoningensis''.

Discovery and naming

The taxon is represented by two near-complete articulated skeletons: 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 several ...

specimen, PMOL AD00114; and a referred specimen, PMOL LFV022. These remains were discovered in the

Barremian The Barremian is an age in the geologic timescale (or a chronostratigraphic stage) between 129.4 ± 1.5 Ma (million years ago) and 121.4 ± 1.0 Ma). It is a subdivision of the Early Cretaceous Epoch (or Lower Cretaceous Series). It is preceded ...

age, 123.2 million years old, Lujiatun 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 ex ...

by local farmers and partially prepared. They were acquired by the

Paleontological Museum of Liaoning 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 fossi ...

Shenyang Shenyang (, ; ; Mandarin pronunciation: ), formerly known as Fengtian () or by its Manchu language, Manchu name Mukden, is a major China, Chinese sub-provincial city and the List of capitals in China#Province capitals, provincial capital of Lia ...

, which completed the preparation. No indications were found that the fossils had been tampered with by fossil thieves. The perfect life-like positions of these specimens suggest that they were buried alive, possibly in their own burrows. In 2020, 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 ...

''Changmiania liaoningensis'' was named and described by Yang Yuqing, Wu Wenhao, Paul-Emile Dieudonné and

Pascal Godefroit Pascal Godefroit is a Belgian paleontologist. He discovered dinosaurs like '' Olorotitan'' in 2003. Godefroit is the director of earth and life sciences This list of life sciences comprises the branches of science that involve the scientific st ...

. The generic name is derived from 長眠 (''cháng mián''), "eternal sleep" in Chinese, referring to the possible sleep position the fossils were found in. The specific name refers to the provenance from

Liaoning 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 ...

Description

The holotype specimen has a preserved length of 117 centimetres. The describing authors established some distinguishing traits. Some of these were

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 ...

, unique derived characters. The

frontal bone The frontal bone is a bone in the human skull. The bone consists of two portions.''Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bony part of the forehead, par ...

s are elongated, over four times longer than wide. The parietals do not share a midline crest. The front branch of the

squamosal bone The squamosal is a skull bone found in most reptiles, amphibians, and birds. In fishes, it is also called the pterotic bone. In most tetrapods, the squamosal and quadratojugal bones form the cheek series of the skull. The bone forms an ancestral co ...

is straight and elongated. On the upper rear corner of the squamosal a distinctive boss is present. The lower edge of the dentary is convex but the edge of the

angular bone The angular is a large bone in the lower jaw (mandible) of amphibians and reptiles (birds included), which is connected to all other lower jaw bones: the dentary (which is the entire lower jaw in mammals), the splenial, the suprangular, and the art ...

is strongly concave, resulting in a sinuous profile for the lower jaw as a whole. The neural spines of the sacral vertebrae are fused into a continuous elongated plate. Both the lower and upper end of the shoulder blade is asymmetrically expanded. The paired ilia are upwards and inwards inclined, covering the sacrum in top view. The upper part of the calfbone is as robust as that of the shinbone.

Phylogeny

In their phylogenetic analysis, Yang ''et al.'' (2020) recovered ''Chiangmiania'' as the basalmost ornithopod. The cladogram below follows their results:

References

External links

The

Smithsonian Magazine ''Smithsonian'' is the official journal published by the Smithsonian Institution in Washington, D.C. The first issue was published in 1970. History The history of ''Smithsonian'' began when Edward K. Thompson, the retired editor of ''Life'' maga ...

{{Taxonbar, from=Q98968277 Ornithopods Fossil taxa described in 2020 Early Cretaceous dinosaurs of Asia Barremian life Yixian fauna Ornithischian genera