Yuxisaurus

This article is about the thyreophoran dinosaur. For the tanystropheid, see Luxisaurus.

Yuxisaurus (meaning "Yuxi lizard") is an extinct genus of basal thyreophoran dinosaur from the Early Jurassic (Sinemurian-Toarcian) Fengjiahe Formation of southwestern China. The type species is Yuxisaurus kopchicki.

Yuxisaurus Temporal range: Early Jurassic, Sinemurian–Toarcian PreꞒ Ꞓ O S D C P T J K Pg N
Skeletal diagram, with osteoderms omitted
Life restoration
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Reptilia
Clade:	Dinosauria
Clade:	†Ornithischia
Clade:	†Thyreophora
Genus:	†Yuxisaurus Yao et al., 2022
Species:	†Y. kopchicki
Binomial name
†Yuxisaurus kopchicki Yao et al., 2022

Discovery and naming

Size compared to a human

Yuxisaurus was first named in a bioRxiv preprint released in late 2021, but was not considered valid, due to having not been validly published.^[1] The taxon was formally published shortly thereafter, in March 2022. The holotype of the taxon, CVEB 21701, represents a partial skeleton including parts of the skull, several vertebrae, elements of the limbs, and at least 120 osteoderms.^[2]

The generic name, "Yuxisaurus," combines a reference to the type locality in Yuxi, Yunnan Province, China, with the Greek "sauros," meaning "lizard." The specific name, "kopchicki," honors the biologist John J. Kopchick.^[2]

Classification

Yuxisaurus was a basal thyreophoran. Depending on the dataset, it may be the sister taxon to the German Emausaurus or more basal than Scelidosaurus and eurypods. The discovery of Yuxisaurus definitively proves that thyreophorans were present in Asia during the Early Jurassic, as other potential records of Early Jurassic Asian thyreophorans, Bienosaurus and Tatisaurus, are too fragmentary to be of any significance.^[2]

Topology 1: Norman dataset Thyreophora Stegosauria "Ankylosauromorpha" Scutellosaurus Emausaurus Yuxisaurus Scelidosaurus Ankylosauria

Topology 2: Maidment et al. dataset Thyreophora Laquintasaura Scutellosaurus Emausaurus Yuxisaurus Scelidosaurus Eurypoda Ankylosauria Stegosauria