Open Paleo

Unaysaurus

Leal et al., 2004 yoo-na-hee-SOR-us

From 'unay', a word meaning 'black water' in the Tupi language indigenous to Brazil, referring to the black-water stream near the discovery site, combined with Greek 'sauros' meaning 'lizard'.

227.3–205.7 million years ago Norian, Late Triassic
Late Triassic stages

Unaysaurus is a genus of herbivorous unaysaurid sauropodomorph dinosaur. Discovered in southern Brazil, in the geopark of Paleorrota, in 1998, and announced in a press conference on Thursday, December 3, 2004, it is one of the oldest dinosaurs known. It is closely related to plateosaurid dinosaurs found in Germany, which indicates that it was relatively easy for species to spread across the giant landmass of the time, the supercontinent of Pangaea. The fossils of Unaysaurus are well-preserved. They consist of an almost complete skull, including a lower jaw, and partial skeleton with many of the bones still connected to each other in their natural positions. It is one of the most complete dinosaur skeletons (including complete skull) ever recovered in Brazil.

Diagnosis

  1. Well developed laterodorsally oriented process formed by frontal and parietal (more developed than in Plateosaurus)
  2. Medial depression on mediodorsal surface of the parietals
  3. Two fossae on the maxillary medial lamina
  4. Deep ventral depression on the basisphenoid
  5. Conspicuous blunt ridge running on lateral surface of deltopectoral crest

Species

Unaysaurus tolentinoi Leal et al., 2004

Type species

Named for Tolentino Marafiga, who discovered the fossils by the side of a road in 1998.

Holotype
UFSM 11069 , Laboratório de Estratigrafia e Paleobiologia, Universidade Federal de Santa Maria
Material
Partial skeleton (about 70% complete) consisting of skull and lower jaw; axis; ten dorsal vertebrae; 30 caudal vertebrae; both scapulae, coracoid, humeri, ulnae, radii; metacarpals and manus elements; incomplete tibiae; right astragalus; left metatarsals and pedal elements.
Horizon
Caturrita Formation, Norian, Late Triassic , 227.3–205.7 million years ago
Locality
Água Negra, Rio Grande do Sul, Brazil

Notable specimens

  • UFSM 11712

    Laboratório de Estratigrafia e Paleobiologia, Universidade Federal de Santa Maria ontogeny

    A skeletally immature individual discovered in association with the holotype, including partial vertebrae and foot material similarly proportioned to the holotype bones; documents an early growth stage of the taxon.

    Müller et al. (2023)

References

  1. Müller, R. T.; Garcia, M. S.; Bem, F. P.; Damke, L. V. S.; Fonseca, A. O.; Da Rosa, Á. A. S. (2023). On a skeletally immature individual of Unaysaurus tolentinoi (Dinosauria: Sauropodomorpha) from the Upper Triassic of southern Brazil. The Anatomical Record 307(4): 1071-1083. doi:10.1002/ar.25285 müller2023a
  2. Leal, L. A.; Azevedo, S. A. K.; Kellner, A. W. A.; Da Rosa, Á. A. S. (2004). A new early dinosaur (Sauropodomorpha) from the Caturrita Formation (Late Triassic), Paran Basin, Brazil. Zootaxa 690(1). Magnolia Press. doi:10.11646/zootaxa.690.1.1 leal2004a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the hip height estimate, and the appearance features.

    jones2026b