Open Paleo

Stokesosaurus

Madsen, 1974 STOHK-so-SAWR-us

Named for Utah geologist William Lee Stokes, who excavated at the Cleveland-Lloyd Dinosaur Quarry where the fossils were found, combined with Greek 'sauros' meaning 'lizard'; meaning 'Stokes' lizard.'

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

Stokesosaurus is a genus of early tyrannosauroid theropod dinosaurs from the late Jurassic period of Utah, United States. They were small, bipedal predators measuring around 3 to 4 meters (9.8 to 13.1 ft) in length.

Diagnosis

  1. Median vertical ridge extending from acetabular hood to dorsal blade margin
  2. Knob on articular surface of pubic peduncle (posterior half, subtriangular)
  3. Premaxilla with height roughly twice anteroposterior length (60mm x 32mm) indicating extremely short snout
  4. Four alveoli in premaxilla with sub-cylindrical teeth bearing serrate edges
  5. Small theropod not exceeding ~4m adult length; ilium blade thin (1mm on medial ridge sides)

Species

Stokesosaurus clevelandi Madsen, 1974

Type species

Named for Cleveland, the town in Utah near the Cleveland-Lloyd Dinosaur Quarry where the holotype was excavated.

Holotype
UMNH VP 7473 , Utah Museum of Natural History
Formerly
UUVP 2938 (rehoused from University of Utah Vertebrate Paleontology Collection)
Material
Left ilium (220mm long, 11cm deep).
Horizon
Brushy Basin Member, Morrison Formation, Kimmeridgian–Tithonian, Late Jurassic , 154.8–143.1 million years ago
Locality
Cleveland-Lloyd Dinosaur Quarry, Utah, United States

References

  1. Madsen, J. H. (1974). A new theropod dinosaur from the Upper Jurassic of Utah. Journal of Paleontology 48(1): 27-31. madsen1974a
  2. Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Theropods. Princeton University Press.

    Source of the hip height estimate.

    jones2026c