Stokesosaurus

Filozoa

Stokesosaurus
Temporal range: Late Jurassic, 152–150 Ma
↓
Fossil remains after the species S. langhami
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Reptilia
Superorder: Dinosauria
Order: Saurischia
Suborder: Theropoda
Superfamily: †Tyrannosauroidea
Genus: †Stokesosaurus
Madsen, 1974
Species
  • S. clevelandi Madsen, 1974 (type)
  • S. langhami Benson, 2008

Stokesosaurus (meaning "Stokes' lizard") is a genus of small (around 3 to 4 meters (10-13 ft) in length), early tyrannosaur from the Late Jurassic period of Utah and England. It was named after Utah geologist William Lee Stokes.[1] Remains possibly referable to Stokesosaurus have been recovered from stratigraphic zone 2 of the Morrison Formation, dated to the late Kimmeridgian age, about 152 million years ago.[2][3]

The holotype (UUVP 2938) consists of a hip bone—originally thought to belong to the possible early tyrannosaur Iliosuchus,[4]—as well as several vertebrae, and a partial braincase.[5] Another ilium referred to this dinosaur[6] is lost but may actually belong to the related Aviatyrannis, and a premaxilla thought to belong to Iliosuchus[1] is actually from Tanycolagreus.

A second species, Stokesosaurus langhami, was described by Roger Benson in 2008 based on a partial skeleton. The skeleton consists of an "associated partial skeleton represented by a complete pelvis" as well as a partially complete leg, as well as neck, back, and tail vertebrae.[7] This second skeleton was discovered in 1984 in Dorset. The specimen was mentioned in several papers, but was not formally described until 2008. The new species was named in honor of Peter Langham, who collected the specimen. The new specimen was discovered in strata dating from the Tithonian, the final stage of the Late Jurassic, indicating the fossil is around 150 million years old.[7]

Stokesosaurus and Tanycolagreus are about the same size, and it is possible that the latter is a junior synonym of the former. However, the ilium (the best known element of Stokesosaurus) of Tanycolagreus has never been recovered, making direct comparison difficult.[8]

References

  1. ^ a b Madsen (1974). "A new theropod dinosaur from the Upper Jurassic of Utah". Journal of Paleontology 48: 27–31. 
  2. ^ Turner, C.E. and Peterson, F., (1999). "Biostratigraphy of dinosaurs in the Upper Jurassic Morrison Formation of the Western Interior, U.S.A." Pp. 77–114 in Gillette, D.D. (ed.), Vertebrate Paleontology in Utah. Utah Geological Survey Miscellaneous Publication 99-1.
  3. ^ Foster, J. (2007). "Appendix." Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. pp. 327-329.
  4. ^ Galton (1976). "Iliosuchus, a Jurassic dinosaur from Oxfordshire and Utah". Palaeontology 19: 587–589. 
  5. ^ Chure and Madsen; Madsen, James (1998). "An unusual braincase (?Stokesosaurus clevelandi) from the Cleveland-Lloyd Dinosaur Quarry, Utah (Morrison Formation; Late Jurassic)". Journal of Vertebrate Paleontology 18 (1): 115–125. doi:10.1080/02724634.1998.10011038. 
  6. ^ Foster and Chure (2000). "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. 
  7. ^ a b Benson, R.B.J. (2008). "New information on Stokesosaurus, a tyrannosauroid (Dinosauria: Theropoda) from North America and the United Kingdom." Journal of Vertebrate Paleontology, 28(3):732-750. doi: 10.1671/0272-4634(2008)28[732:NIOSAT]2.0.CO;2.
  8. ^ Foster, J. (2007). Jurassic West: The Dinosaurs of the Morrison Formation and Their World. Indiana University Press. 389pp.

External links