Open Paleo

Irisosaurus

Peyre de Fabrègues et al., 2020 EYE-rih-so-SAWR-us

Named after the iridescent clouds (iris = iridescent) of Yunnan Province, China; meaning "iridescent lizard"

201.4–174.7 million years ago Hettangian–Toarcian, Early Jurassic
Early Jurassic stages

Irisosaurus is an extinct genus of sauropodiform sauropodomorph dinosaur, from the Fengjiahe Formation of China. The type species, Irisosaurus yimenensis was formally described in 2020. It was the sister taxon to Mussaurus.

Diagnosis

  1. Large and deep neurovascular foramen within perinarial fossa opening anteriorly, unique to Irisosaurus
  2. Deep perinarial fossa defined by sharp rim along elongate curved ridge of premaxillary ramus
  3. Premaxillary ramus of maxilla markedly higher than long prior to nasal process
  4. Strongly asymmetrical proximal half of metacarpal V with proximomedial corner much anterior to proximolateral corner
  5. Teeth lacking denticles on carinae, convergent with Yunnanosaurus huangi

Species

Irisosaurus yimenensis Peyre de Fabrègues et al., 2020

Type species

Named for Yimen County, Yunnan, China, the locality where the holotype was found.

Holotype
CVEB 21901 , Centre for Vertebrate Evolutionary Biology, Yunnan University
Material
Partial skeleton including partial left maxilla, partial right dentary, three isolated teeth, five partial cervical vertebrae, three partial dorsal vertebrae, nearly complete right and partial left scapulocoracoid, nearly complete right humerus and partial left, complete right radius, two partial manus with carpals, two distal ischia ends, partial pes ungual phalanx
Horizon
upper Fengjiahe Formation, Hettangian–Toarcian, Early Jurassic , 201.4–174.7 million years ago
Locality
Jiaojiadian area B, near Zhanmatian village, Yunnan, China

References

  1. Peyre de Fabrègues, C.; Bi, S.; Li, H.; Li, G.; Yang, L.; Xu, X. (2020). A new species of early-diverging Sauropodiformes from the Lower Jurassic Fengjiahe Formation of Yunnan Province, China. Scientific Reports 10(1). Springer Science and Business Media LLC. doi:10.1038/s41598-020-67754-4 peyredefabrègues2020a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the body length, mass, and hip height estimates, and the appearance features.

    jones2026b