Yinshanosaurus
Yinshanosaurus is an extinct genus of pareiasaurian parareptiles from the Late Permian 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 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 vertebrae, thirteen dorsal vertebrae and three isolated dorsal neural spines, several ribs, and the acetabular part of the left ilium. Several osteoderms 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, 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 of Yinshanosaurus.Prior to its formal naming, the fossil material was first announced in 2024 in an unreviewed preprint hosted by bioRxiv. However, the taxon was considered informally named as the manuscript did not yet meet the necessary requirements of the International [Code of Zoological Nomenclature]. 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 (biology)|type locality] is in, with the Ancient Greek σαῦρος, meaning "lizard". The specific name, angustus, is a Latin word meaning "narrow", referencing the slender morphology of the skull compared to other pareiasaurs.