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

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

of basal

ornithopod Ornithopoda () is a clade of ornithischian dinosaurs, called ornithopods (). They represent one of the most successful groups of herbivorous dinosaurs during the Cretaceous. The most primitive members of the group were bipedal and relatively sm ...

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

that lived in what is now

China China, officially the People's Republic of China (PRC), is a country in East Asia. With population of China, a population exceeding 1.4 billion, it is the list of countries by population (United Nations), second-most populous country after ...

during the

Early Cretaceous The Early Cretaceous (geochronology, geochronological name) or the Lower Cretaceous (chronostratigraphy, chronostratigraphic name) is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 143.1 ...

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

Discovery and naming

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

holotype A holotype (Latin: ''holotypus'') is a single physical example (or illustration) of an organism used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of s ...

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 125.77 Ma (million years ago) and 121.4 ± 1.0 Ma (Historically, this stage was placed at 129.4 million to approximately 125 million years ago) It is a ...

age, 123.2 million years old, Lujiatun Beds of the

Yixian Formation The Yixian Formation (; formerly Romanization of Chinese, transcribed as Yihsien Formation or Yixiang Formation) is a geological formation in Jinzhou, Liaoning, People's Republic of China, that spans the Barremian stage of the Early Cretaceous. I ...

by local farmers and partially prepared. They were acquired by the Paleontological Museum of Liaoning at

Shenyang Shenyang,; ; Mandarin pronunciation: ; formerly known as Fengtian formerly known by its Manchu language, Manchu name Mukden, is a sub-provincial city in China and the list of capitals in China#Province capitals, provincial capital of Liaonin ...

, 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 due to a volcanic eruption. In 2020, the

type species In International_Code_of_Zoological_Nomenclature, 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 spe ...

''Changmiania liaoningensis'' was named and described by Yang Yuqing, Wu Wenhao, Paul-Emile Dieudonné and Pascal Godefroit. 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 Specific name may refer to: * in Database management systems, a system-assigned name that is unique within a particular database In taxonomy, either of these two meanings, each with its own set of rules: * Specific name (botany), the two-part (bino ...

refers to the provenance from

Liaoning ) , image_skyline = , image_alt = , image_caption = Clockwise: Mukden Palace in Shenyang, Xinghai Square in Dalian, Dalian coast, Yalu River at Dandong , image_map = Liaoning in China (+all claims hatched).svg , ...

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 ...

, unique derived characters. The

frontal bone In the human skull, the frontal bone or sincipital bone is an unpaired bone which consists of two portions.'' Gray's Anatomy'' (1918) These are the vertically oriented squamous part, and the horizontally oriented orbital part, making up the bo ...

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 ...

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 ...

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. The neck was very short, with only six vertebrae; other ornithischians usually have nine.

Phylogeny

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

Paleobiology

''Changmiania'' probably dug burrows, like several other small ornithischians such as '' Oryctodromeus''. Several of its anatomical features, such as its short neck, short forearm and hands, and enlarged shoulder bones are probably adaptations for digging.

References

External links

The

Smithsonian Magazine ''Smithsonian'' is a magazine covering science, history, art, popular culture and innovation. The first issue was published in 1970. History The history of ''Smithsonian'' began when Edward K. Thompson, the retired editor of ''Life'' magazine ...

{{Taxonbar, from=Q98968277 Thescelosauridae Dinosaur genera Barremian dinosaurs Yixian Formation Taxa named by Pascal Godefroit Fossil taxa described in 2020 Dinosaurs of China