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Suuwassea

Harris & Dodson, 2004 SOO-oo-WAH-see-uh

From the Crow language, derived from 'suuwassa' meaning 'the first thunder heard in spring'; the root 'suu' means 'thunder' and 'wassa' means 'ancient', evoking the 'thunder lizard' epithet often applied to sauropods.

154.8–143.1 million years ago Kimmeridgian–Tithonian, Late Jurassic
Late Jurassic stages

Suuwassea is a genus of dicraeosaurid sauropod dinosaur found in Upper Jurassic strata of the Morrison Formation, located in southern Carbon County, Montana, United States. The fossil remains were recovered in a series of expeditions during a period spanning the years 1999 and 2000 and were described by J.D. Harris and Peter Dodson in 2004. They consist of a disarticulated but associated partial skeleton, including partial vertebral series and limb bones.

Diagnosis

  1. Supraoccipital with ventral end drawn out into narrow, elongate process contributing minimally to foramen magnum margin
  2. Basioccipital not contributing to dorsal side of occipital condylar neck
  3. Antotic processes of laterosphenoid separated from frontals by deep notches
  4. Cranial cervical neural spines restricted to caudal halves of centra, craniocaudally compressed, expanded distally, and not bifurcate
  5. Distal caudal centra ("whiplash" form) amphiplatyan
  6. Dorsal tuberculum of humerus well developed
  7. Proximal articular surface of tibia wider mediolaterally than long craniocaudally
  8. Calcaneus spheroidal
  9. Pedal phalanges longer proximodistally than wide mediolaterally

Species

Suuwassea emilieae Harris & Dodson, 2004

Type species

Named for Emilie deHellebranth (1914-2001), the deceased sponsor of the expeditions that recovered the fossil material.

Holotype
ANS 21122 , Academy of Natural Sciences of Philadelphia
Material
Partial skeleton including premaxilla, maxilla, quadrate, complete braincase, cervical and dorsal vertebrae, ribs, caudal centra, scapula, coracoid, humerus, tibia, fibula, calcaneus, metatarsals and pedal phalanges
Horizon
Morrison Formation, Kimmeridgian–Tithonian, Late Jurassic , 154.8–143.1 million years ago
Locality
Rattlesnake Ridge Quarry, Montana, United States Harris and Dodson (2004) give the horizon as "?Tithonian", and Tschopp and colleagues (2015) as "Late Kimmeridgian"; neither states a basis.

References

  1. Tschopp, E.; Mateus, O.; Benson, R. B. J. (2015). A specimen-level phylogenetic analysis and taxonomic revision of Diplodocidae (Dinosauria, Sauropoda). PeerJ 3: e857. PeerJ. doi:10.7717/peerj.857

    Lists the holotype from Rattlesnake Ridge Quarry as "Late Kimmeridgian; Lower Morrison Form.".

    tschopp2015a
  2. Harris, J. D.; Dodson, P. (2004). A new diplodocoid sauropod dinosaur from the Upper Jurassic Morrison Formation of Montana, USA. Acta Palaeontologica Polonica 49(2): 197-210. doi:10.5281/zenodo.13506584 harris2004a
  3. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Sauropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026b