Torosaurus
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[Photo] Life-sized bronze Torosaurus statue at the Peabody Museum of Natural History at Yale University. Date: 22 March 2006. Photo by Ragesoss

Torosaurus ("perforated lizard") was a ceratopsid dinosaur species. It had one of the largest skulls of any land animal known, reaching 8.5 feet (2.6 meters) in length ??? surpassed only by a recently-described 10 foot (3 meter) skull of Pentaceratops. From head to tail, Torosaurus probably measured about 25 feet (7.6 meters) long and weighed an estimated 4.4 to 6.6 tons (4 to 6 tonnes).

Discoveries and species
Two Torosaurus skulls were discovered in southeastern Wyoming by John Bell Hatcher in 1891 and the species was subsequently named by Othniel Charles Marsh in 1891, two years after Triceratops.

Remains have since been found in Wyoming, Montana, South Dakota, North Dakota, Utah and Saskatchewan. Some fragmentary remains, which may be Torosaurus, have been found in the Big Bend Region of Texas and in the San Juan Basin of New Mexico. Fossil evidence suggests it may have been uncommon; remains of its relative Triceratops are more frequently found.

Torosaurus species:

T. latus Marsh, 1891 (type species)

Misassignments:

T. gladius Marsh, 1891 (=T. latus)
T. utahensis Lawson, 1976 (=T. latus)

(NB: The last species was originally described as Arrhinoceratops utahensis by Gilmore in 1946. Review by Sullivan et al. in 2005 has left it as Torosaurus utahensis and somewhat older than T. latus.

Although the name Torosaurus is frequently translated as 'bull lizard' (from the Latin 'taurus' (bull), it probably means 'perforated lizard' (from the Greek word 'toreo' (pierce, perforate). The name refers to the holes, or fenestrae, in the frill of this animal. This was probably intended by Othniel Charles Marsh (the original namer) to contrast with the condition in Triceratops, which had a solid frill. Much of this confusion results from the fact that Marsh never explicitly gave the etymology of the name in his papers.

Classification
Torosaurus belonged to the subfamily known as Chasmosaurinae, within the family Ceratopsidae, within the Ceratopsia (which name is Ancient Greek for "horned face"), a group of herbivorous dinosaurs with parrot-like beaks which thrived in North America and Asia during the Jurassic and Cretaceous Periods. Recent studies indicate that Torosaurus is most closely related to Triceratops. Jack Horner has suggested in public lectures that Torosaurus may in fact represent the adult version of one sex of Triceratops, pointing out that there are no juvenile specimens of Torosaurus and that approximately 50% of all subadult Triceratops skulls have two thin areas in the frill that correspond with the placement of "holes" in Torosaurus skulls. The theory is that all Tricertops had solid frills up to adulthood, but on reaching sexual maturity, one sex or the other would have developed longer frills as a form of display. To counterbalance the extra weight of the elongated frill, holes would have necessarily developed in the bone. While this theory does explain the absence of any Torosaurus specimens younger than adults and also explains the even split between uniformly thick frills and frills with thin patches in subadult Triceratops specimens, the theory is not widely accepted in the scientific community and has apparently not been put forward by Dr. Horner outside of informal lectures.

Paleobiology
Torosaurus, like all ceratopsians, was an herbivore. During the Cretaceous, flowering plants were "geographically limited on the landscape", so it is likely that this dinosaur fed on the predominant plants of the era: ferns, cycads and conifers. It would have used its sharp beak to bite off the leaves or needles.

In popular culture
Torosaurus was featured in the BBC and Discovery Channel special, Walking with Dinosaurs.
It was also featured in the Vivendi Universal game, Jurassic Park: Operation Genesis.
"Torosaurus" is a nickname for Ray Toro, the guitarist in the band My Chemical Romance.

http://en.wikipedia.org/wiki/Torosaurus

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