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''Zhongyuansaurus'' (meaning "Zhongyuan lizard") is an extinct genus of ankylosaurid dinosaurs known from 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 ...
Haoling Formation of what is now Henan Province, China. The genus contains two species, ''Z. luoyangensis'', named in 2007, and ''Z. junchangi'', named in 2025, both known from a single partial skeleton. ''Zhongyuansaurus'' is similar to '' Gobisaurus'', prompting some researchers to regard the genera as
synonymous A synonym is a word, morpheme, or phrase that means precisely or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are a ...
.


Discovery and naming

The ''Zhongyuansaurus''
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 ...
, ''Z. luoyangensis'', was named and described in 2007 by Xu and colleagues. 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, HGM 41HIII-0002, consists of a nearly complete skull, fragments of the lower jaw, a cervical neural spine, dorsal vertebrae, caudal vertebrae, posterior caudal vertebral centra, fused distal caudal vertebrae, ribs, a humerus, both ischia, a pubis, and osteoderms. The specimen was collected from the Haoling Formation in
Henan Province Henan; alternatively Honan is a province in Central China. Henan is home to many heritage sites, including Yinxu, the ruins of the final capital of the Shang dynasty () and the Shaolin Temple. Four of the historical capitals of China, Luo ...
of Ruyang County, China. The specimen is accessioned at the Henan Province Geological Museum in China. The generic name, ''Zhongyuansaurus'', is derived from "
Zhongyuan Zhongyuan (), the Central Plain(s), also known as Zhongtu (, lit. 'central land') and Zhongzhou (, lit. 'central region'), commonly refers to the part of the North China Plain surrounding the lower and middle reaches of the Yellow River, centere ...
", after the area south of Yellow River area, and the Greek word ''sauros'', meaning "lizard". The specific name, ''luoyangensis'', refers to the
Luoyang Luoyang ( zh, s=洛阳, t=洛陽, p=Luòyáng) is a city located in the confluence area of the Luo River and the Yellow River in the west of Henan province, China. Governed as a prefecture-level city, it borders the provincial capital of Zheng ...
area where the holotype was found. In a 2015 publication, Victoria Arbour and Phillip J. Currie determined that ''Zhongyuansaurus'' may be a
junior synonym In taxonomy, the scientific classification of living organisms, a synonym is an alternative scientific name for the accepted scientific name of a taxon. The botanical and zoological codes of nomenclature treat the concept of synonymy differently. ...
of '' Gobisaurus domoculus'', as they recognized all the diagnosable characteristics of ''Gobisaurus'' in the ''Zhongyuansaurus'' holotype, except where these could not be assessed due to damage. In 2025, Zhang et al. described ''Zhongyuansaurus junchangi'' as a new species in the genus based on the holotype, 41HIII0708, which comprises a right mandible, 14 free caudal verterbae and seven fused caudal vertebrae forming the club 'handle', ten
haemal arch A haemal arch, also known as a chevron, is a bony arch on the ventral side of a tail vertebra of a vertebrate. The canal formed by the space between the arch and the vertebral body is the haemal canal. A spinous ventral process emerging from the ha ...
es, four ribs, the left humerus, one metatarsal, and 41 osteoderms. The specific name, ''junchangi'', honors Chinese paleontologist Lü Junchang and his work in Henan. They noted several characteristics that could be used to distinguish ''Zhongyuansaurus'' from other Asian ankylosaurids, including ''Gobisaurus'' and '' Shamosaurus'' (an ankylosaurid similar to ''Gobisaurus''). The specimen was found in the same rock layers as ''Z. luoyangensis''.


Description

''Zhongyuansaurus'', like other ankylosaurids, had numerous
osteoderms Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of Extant taxon, extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, Temnospondyli, ...
embedded in the skin. In their 2007 description, Xu et al. recognised eight different sets of osteoderms pertaining to the holotype specimen. These osteoderms include a large, thin irregular quadrangle osteoderms that may have been located on the front portion of the back, large, thick, irregular quadrangle osteoderms that had a flat surface, and front edges that extend considerably downwards, circular osteoderms that have an off centred keel on the outer surface, asymmetrical circular osteoderms that have a well developed keel on the outer surface, small circular osteoderms that have irregular grooves and no ridges on the outer surface, hollow cone osteoderms that have an irregular grooved sculpture on the outer surface, kidney shaped osteoderms that have the sides folded upwards and one edge being thicker than the other, and ridge shaped osteoderms that have an irregular grooved sculpture on the outer surface. An arrow-shaped bone with a pointed end was found near the region of the
nasal Nasal is an adjective referring to the nose, part of human or animal anatomy. It may also be shorthand for the following uses in combination: * With reference to the human nose: ** Nasal administration, a method of pharmaceutical drug delivery * ...
. Xu et al. (2007) interpreted it as a nasal horn homologous to other osteoderms that would have protruded from the nasal bone on an angle without being fused to the bone, a feature not seen in any ankylosaur. The authors suggested that the nasal horn may have been used for intraspecific and interspecific combat. The tail club of ''Zhongyuansaurus'' only preserves the "handle" and no "knob" osteoderms. The holotype preserves the terminal
caudal vertebrae Caudal vertebrae are the vertebrae of the tail in many vertebrates. In birds, the last few caudal vertebrae fuse into the pygostyle, and in apes, including humans, the caudal vertebrae are fused into the coccyx. In many reptiles, some of the caud ...
, so the absence of the “knob” osteoderms is not because the distal end of the tail is missing. Although the holotype specimen represents an immature individual based on cranial sutures,
ontogeny Ontogeny (also ontogenesis) is the origination and development of an organism (both physical and psychological, e.g., moral development), usually from the time of fertilization of the ovum, egg to adult. The term can also be used to refer to t ...
does not seem to be an explanation for the absence of the knob osteoderms. In 2015, Arbour & Currie proposed alternate explanations for the lack of knob osteoderms; if they may were present in life, they were likely small and not firmly articulated to the handle, thus becoming disarticulated after death. However, they also noted that isolated tail club knobs from ankylosaurines often preserve some fragments of the distal caudal vertebrae or ossified
tendons A tendon or sinew is a tough band of dense fibrous connective tissue that connects muscle to bone. It sends the mechanical forces of muscle contraction to the skeletal system, while withstanding tension. Tendons, like ligaments, are made of ...
associated with the knob osteoderms. Since the distalmost caudal vertebrae are all preserved, this may indicate the lack of knob osteoderms altogether.


Classification

Xu et al., 2007 originally considered ''Zhongyuansaurus'' to be a nodosaurid ankylosaur based on the skull proportions and the absence of a tail club. However, longer-than-wide skulls are a pleiomorphic trait of
Ankylosauria Ankylosauria is a group of herbivorous dinosaurs of the clade Ornithischia. It includes the great majority of dinosaurs with armor in the form of bony osteoderms, similar to turtles. Ankylosaurs were bulky quadrupeds, with short, powerful limbs ...
and not a derived condition of nodosaurids. Carpenter et al., 2008 re-evaluated ''Zhongyuansaurus'' to the clade Shamosaurinae based on similarities with '' Shamosaurus''. Thompson et al. (2012) recovered ''Zhongyuansaurus'' as a basal ankylosaurine and Arbour & Currie (2015) later concluded that ''Zhongyuansaurus'' was a probable junior synonym of '' Gobisaurus''. A phylogenetic analysis conducted by Thompson et al. (2012) is reproduced below.


Paleoenvironment

''Zhongyuansaurus'' was recovered from the Haoling Formation, which possibly dates to the
Aptian The Aptian is an age (geology), age in the geologic timescale or a stage (stratigraphy), stage in the stratigraphic column. It is a subdivision of the Early Cretaceous, Early or Lower Cretaceous epoch (geology), Epoch or series (stratigraphy), S ...
and
Albian The Albian is both an age (geology), age of the geologic timescale and a stage (stratigraphy), stage in the stratigraphic column. It is the youngest or uppermost subdivision of the Early Cretaceous, Early/Lower Cretaceous epoch (geology), Epoch/s ...
stages of 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 ...
. ''Zhongyuansaurus'' would have shared its habitat with the oviraptorid '' Luoyanggia'', the
sauropods Sauropoda (), whose members are known as sauropods (; from '' sauro-'' + '' -pod'', 'lizard-footed'), is a clade of saurischian ('lizard-hipped') dinosaurs. Sauropods had very long necks, long tails, small heads (relative to the rest of their b ...
'' Xianshanosaurus'', '' Yunmenglong'', '' Ruyangosaurus'' and '' Huanghetitan'', an indeterminate ornithomimid, an indeterminate iguanodontian, and an indeterminate carcharodontosaurian.


See also

*
Timeline of ankylosaur research This timeline of ankylosaur research is a chronological listing of events in the History of paleontology, history of paleontology focused on the ankylosaurs, quadrupedal herbivorous dinosaurs who were protected by a covering bony plates and spik ...


References

{{Taxonbar, from=Q135722 Ankylosaurinae Dinosaur genera Aptian dinosaurs Albian dinosaurs Dinosaurs of China Fossil taxa described in 2007 Taxa named by Lü Junchang