Named By: Madsen - 1974.
Classification: Chordata, Reptilia, Dinosauria, Saurischia, Theropoda, Tyrannosauroidea.
Species: S. clevelandi (type).
Size: Estimated 3 - 4 meters long.
Known locations: USA, Utah - Morrison Formation.
Time period: Kimmeridgian of the Jurassic.
Fossil representation: Several specimens of partial remains.
back around one-hundred and fifty-two million years ago,
Stokesosaurus is one of the earliest
representatives of the
lineage, being only slightly later than Guanlong.
to four meters long, Stokesosaurus resembled the
juvenile forms of
later tyrannosarids, and was a fleet footed predator relying upon
speed to catch prey. Stokesosaurus probably
remained at these smaller
sizes because other larger predators such as Allosaurus
at the time. By staying smaller and faster, Stokesosaurus
focus upon hunting prey that was too fast and nimble for Allosaurus
The description of Aviatyrannis in 2003 was initially taken as representing another early tyrannosaurid dinosaur that was similar to Stokesosaurus. However some palaeontologists have pointed out the similarity between the scant partial remains of Aviatyrannis and the better known Stokesosaurus, as such the possibility that Aviatyrannis is a junior synonym to Stokesosaurus is recognised by most. Another potential synonym for Stokesosaurus is Tanycolagreus. Again however, the lack of matching fossil material (particularly the ilium) makes it difficult to be certain.
One former species of Stokesosaurus, S. langhami from England has now been described as a a new genus, Juratyrant.
- A new theropod dinosaur from the Upper Jurassic of Utah. - Journal of Paleontology 48(1):27-31. - J. H. Madsen Jr - 1974.
- An unusual braincase (?Stokesosaurus clevelandi) from the Cleveland-Lloyd Dinosaur Quarry, Utah (Morrison Formation; Late Jurassic). - Journal of Vertebrate Paleontology 18 (1): 115–125. - D. Chure & J. Madsen - 1998.
- An ilium of a juvenile Stokesosaurus (Dinosauria, Theropoda) from the Morrison Formation (Upper Jurassic: Kimmeridgian), Meade County, South Dakota. - Brigham Young University Geology Studies 45: 5–10. - J. Foster & D. Chure - 2000.
- New small theropod from the Upper Jurassic Morrison Formation of Wyoming. - In The Carnivorous Dinosaurs. Indiana University Press, Bloomington pp. 23-48, by K. Carpenter - K. Carpenter, C.A. Miles & K.C. Cloward - 2005.