''Yinshanosaurus'' is an

extinct Extinction is the termination of an organism by the death of its Endling, last member. A taxon may become Functional extinction, functionally extinct before the death of its last member if it loses the capacity to Reproduction, reproduce and ...

genus of

pareiasauria Pareiasaurs (meaning "cheek lizards") are an extinct clade of large, herbivorous parareptiles. Members of the group were armoured with osteoderms which covered large areas of the body. They first appeared in southern Pangea during the Middle Per ...

parareptile Parareptilia ("near-reptiles") is an extinct group of Basal (phylogenetics), basal Sauropsida, sauropsids ("Reptile, reptiles"), traditionally considered the sister taxon to Eureptilia (the group that likely contains all living reptiles and birds ...

s from the

Late Permian Late or LATE may refer to: Everyday usage * Tardy, or late, not being on time * Late (or the late) may refer to a person who is dead Music * ''Late'' (The 77s album), 2000 * Late (Alvin Batiste album), 1993 * Late!, a pseudonym used by Dave Groh ...

Naobaogou Formation of China. The genus contains a single species, ''Yinshanosaurus angustus'', known from a partial skeleton including a skull and an additional isolated skull.

Discovery and naming

The ''Yinshanosaurus''

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, IVPP V 33181, was collected in 2018 from outcrops of the Naobaogou Formation near Qiandian Village in Inner Mongolia, China. It consists of a partial articulated skeleton, including a skull, both scapulocoracoids, the third–fifth cervical (neck)

vertebrae Each vertebra (: vertebrae) is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal ...

, thirteen dorsal (back) vertebrae and three isolated dorsal neural spines, several

rib In vertebrate anatomy, ribs () are the long curved bones which form the rib cage, part of the axial skeleton. In most tetrapods, ribs surround the thoracic cavity, enabling the lungs to expand and thus facilitate breathing by expanding the ...

s, and the acetabular part of the left ilium. Several

osteoderm Osteoderms are bony deposits forming scales, plates, or other structures based in the dermis. Osteoderms are found in many groups of extant and extinct reptiles and amphibians, including lizards, crocodilians, frogs, temnospondyls (extinct amph ...

s are preserved in association with the vertebral column. The skull is eroded and crushed but otherwise nearly complete. An additional nearly complete skull, SXNHM V0010.12, was collected in 2015 from the Sunjiagou Formation of

Shanxi Shanxi; Chinese postal romanization, formerly romanised as Shansi is a Provinces of China, province in North China. Its capital and largest city of the province is Taiyuan, while its next most populated prefecture-level cities are Changzhi a ...

, China. This formation is likely similar in age to the Naobaogou Formation. Based on similarities to the holotype, SXNHM V0010.12 was referred as the

paratype In zoology and botany, a paratype is a specimen of an organism that helps define what the scientific name of a species and other taxon actually represents, but it is not the holotype (and in botany is also neither an isotype (biology), isotype ...

of ''Yinshanosaurus''. Prior to its formal naming, the fossil material was first announced in 2024 in an unreviewed

preprint In academic publishing, a preprint is a version of a scholarly or scientific paper that precedes formal peer review and publication in a peer-reviewed scholarly or scientific journal. The preprint may be available, often as a non-typeset versi ...

hosted by

bioRxiv bioRxiv (pronounced "bio-archive") is an open access preprint repository for the biological sciences co-founded by John Inglis and Richard Sever in November 2013. It was hosted by Cold Spring Harbor Laboratory (CSHL) until March 11, 2025, whe ...

. However, the taxon was considered informally named as the manuscript did not yet meet the necessary requirements of the

International Code of Zoological Nomenclature The International Code of Zoological Nomenclature (ICZN) is a widely accepted Convention (norm), convention in zoology that rules the formal scientific name, scientific naming of organisms treated as animals. It is also informally known as the I ...

(ICZN). In 2025, Jian Yi and Jun Liu formally described ''Yinshanosaurus angustus'' as a new genus and species of pareiasaurs based on these fossil remains. The generic name, ''Yinshanosaurus'', combines "Yinshan", the ancient name of the mountain the type locality is in, with the

Ancient Greek Ancient Greek (, ; ) includes the forms of the Greek language used in ancient Greece and the classical antiquity, ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Greek ...

'' σαῦρος'' (''sauros''), meaning "lizard". The specific name, ''angustus'', is a

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

word meaning "narrow", referencing the slender morphology of the skull compared to other pareiasaurs.

Classification

In their 2025

phylogenetic analyses In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as Computational phylogenetics, phylogenetic inference. It infers the relationship among organ ...

, Yi and Liu recovered ''Yinshanosaurus'' as a deeply-nested member of the Pareiasauria as the

sister taxon In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and ...

to a species named in 2019 as a member of the genus '' Shihtienfenia'', ''S. completus''. This species, found in the Sunjiagou Formation of China from which the ''Yinshanosaurus'' paratype is also known, is known from a complete skull and mandible. However, their results placed ''S. permica'', 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 ...

of ''Shihtienfenia'', in a disparate part of the tree, suggesting ''S. completus'' should not be included in that genus. The clade containing ''Yinshanosaurus'' and "''Shihtienfenia''" ''completus'' was found to be the sister group to the clade Pumiliopareiasauria, with this clade in turn the sister to the Therischia. The results are displayed in the

cladogram A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...

below, with Chinese pareiasaurs highlighted and both ''Shihtienfenia'' species in a darker shade.

References

{{Taxonbar, from1=Q134710726, from2=Q134710727 Pareiasauria Prehistoric reptile genera Permian Russia Fossils of Russia Fossil taxa described in 2025