Stokesosaurus

Stokesosaurus
	The holotype of Stokesosaurus clevelandi , a left iliac bone .
Temporal occurrence
	Upper Jurassic (Lower Tithonian )
	152.1 to 147.7 million years
Locations
	Utah , North America ( Morrison Formation );
Systematics
	Lizard dinosaur (Saurischia)
	Theropoda
	Tetanurae
	Coelurosauria
	Tyrannosauroidea
	Stokesosaurus
Scientific name
	Stokesosaurus
	Madsen , 1974
Art
	Stokesosaurus clevelandi;

Stokesosaurus is a genus of theropod dinosaur and an early member of the Tyrannosauroidea thatlived in North Americaduring the Upper Jurassic (Lower Tithonian ). As with all theropods, it was a two-legged carnivore; with an estimated body length between 2.5 and 4 meters, it was a smaller representative of the Tyrannosauroidea. Currently, only two ilia , which come from the Morrison Formation in the US state of Utah , can be safely assigned to this genus. Other finds were once attributed to this genus, but their affiliation to Stokesosaurus has meanwhile been questioned or rejected. In addition to the type species Stokesosaurus clevelandi ,a second species was describedin 2008 with Stokesosaurus langhami , which, however, was rewritten in2012 as an independent genus, Juratyrant .

features

The iliac bone (holotype specimen) is about 22 cm long, which, according to Madsen (1974), indicates a relatively small theropod that did not exceed 4 meters in length. Paul (2010) estimated the body length to be 2.5 meters and the weight to be 60 kilograms. The iliac bone can be distinguished from related genera by a number of unique features ( autapomorphies ): This bone shows a semi-oval outline when viewed from the side; also was in before the acetabular cup (acetabulum) a thin notch, while above the acetabulum extends a vertically oriented, pronounced ridge.

Find and story of discovery

Since 1960, geologist William Lee Stokes and his assistant James Madsen excavated the Cleveland-Lloyd dinosaur quarry . In addition to thousands of bones of the theropod Allosaurus , the finds also included the remains of previously unknown species. The new species and genus Stokesosaurus clevelandi was first described by James Madsen in 1974 based on a left iliac bone ( holotype , copy number UUVP 2938) as well as a left iliac bone and an intermaxillary bone . The name honors William Lee Stokes for his work in the Cleveland-Lloyd dinosaur quarry, the species name refers to the city of Cleveland in Utah. The intermaxillary bone was assigned to the genus Tanycolagreus in 2005 , but Benson (2008) suspects that it actually belongs to a Ceratosauria .

Since the first description, various other fossils have been assigned to the genus. Also a small, right iliac bone from the Wonderland quarry in South Dakota , which has been lost and probably cannot be attributed to Stokesosaurus . Britt (1991) tentatively attributed various vertebrae to Stokesosaurus ; Chure and Madsen (1998) meanwhile assigned an isolated brain skull to the genus . According to other researchers, however, common features with the Stokesosaurus type fossils are missing, which is why these assignments are not justified.

A second species, Stokesosaurus langhami , was described by Roger Benson in 2008 based on a partial skeleton. From this skeleton, which was discovered by Peter Langham in Dorset ( England ) in 1984 , parts of the pelvis, sacrum, various vertebrae as well as the upper and lower legs have been preserved. However, a recent study from 2012 describes this species as a new genus, Juratyrant .

Individual evidence

↑ ^a ^b ^c ^d ^e ^f Roger BJ Benson: New information on Stokesosaurus, a tyrannosauroid (Dinosauria: Theropoda) from North America and the United Kingdom. In: Journal of Vertebrate Paleontology. Vol. 28, No. 3, 2008, ISSN 0272-4634 , pp. 732-750, doi : 10.1671 / 0272-4634 (2008) 28 [732: NIOSAT] 2.0.CO; 2 .
↑ ^a ^b Stephen L. Brusatte, Roger BJ Benson: The systematics of Late Jurassic tyrannosauroid theropods from Europe and North America. In: Acta Palaeontologica Polonica. Vol. 58, No. 1, 2013, ISSN 0567-7920 , pp. 47-54, doi : 10.4202 / app.2011.0141 .
↑ ^a ^b James H. Madsen: A new theropod dinosaur from the upper Jurassic of Utah. In: Journal of Paleontology. Vol. 48, No. 1, 1974, ISSN 0022-3360 , pp. 27-31.
^ Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ 2010, ISBN 978-0-691-13720-9 , p. 100, online .
↑ Kenneth Carpenter , Clifford Miles, Karen Cloward: New small theropod from the Upper Jurassic Morrison Formation of Wyoming. In: Kenneth Carpenter (Ed.): The Carnivorous Dinosaurs. Indiana University Press, Bloomington IN et al. 2005, ISBN 0-253-34539-1 , pp. 23-48.
^ Daniel J. Chure, James H. Madsen: An unusual braincase (? Stokesosaurus clevelandi) from the Cleveland-Lloyd Dinosaur Quarry, Utah (Morrison Formation; Late Jurassic). In: Journal of Vertebrate Paleontology. Vol. 18, No. 1, 1998, pp. 115-125, doi : 10.1080 / 02724634.1998.10011038 .

[benson2008-1] ↑ ^a ^b ^c ^d ^e ^f Roger BJ Benson: New information on Stokesosaurus, a tyrannosauroid (Dinosauria: Theropoda) from North America and the United Kingdom. In: Journal of Vertebrate Paleontology. Vol. 28, No. 3, 2008, ISSN 0272-4634 , pp. 732-750, doi : 10.1671 / 0272-4634 (2008) 28 [732: NIOSAT] 2.0.CO; 2 .

[brusatte&benson2012-2] Stephen L. Brusatte, Roger BJ Benson: The systematics of Late Jurassic tyrannosauroid theropods from Europe and North America. In: Acta Palaeontologica Polonica. Vol. 58, No. 1, 2013, ISSN 0567-7920 , pp. 47-54, doi : 10.4202 / app.2011.0141 .

[madsen1974-3] James H. Madsen: A new theropod dinosaur from the upper Jurassic of Utah. In: Journal of Paleontology. Vol. 48, No. 1, 1974, ISSN 0022-3360 , pp. 27-31.

[paul_10-4] Gregory S. Paul : The Princeton Field Guide To Dinosaurs. Princeton University Press, Princeton NJ 2010, ISBN 978-0-691-13720-9 , p. 100, online .

[carpenter_05-5] Kenneth Carpenter , Clifford Miles, Karen Cloward: New small theropod from the Upper Jurassic Morrison Formation of Wyoming. In: Kenneth Carpenter (Ed.): The Carnivorous Dinosaurs. Indiana University Press, Bloomington IN et al. 2005, ISBN 0-253-34539-1 , pp. 23-48.

[chure&madsen1998-6] Daniel J. Chure, James H. Madsen: An unusual braincase (? Stokesosaurus clevelandi) from the Cleveland-Lloyd Dinosaur Quarry, Utah (Morrison Formation; Late Jurassic). In: Journal of Vertebrate Paleontology. Vol. 18, No. 1, 1998, pp. 115-125, doi : 10.1080 / 02724634.1998.10011038 .