Torosaurus

Taxobox
name = "Torosaurus"

---

image_width = 240px
image_caption = "Torosaurus latus"
fossil_range = Late Cretaceous
regnum = Animalia
phylum = Chordata
classis = Sauropsida
superordo = Dinosauria
ordo = Ornithischia
subordo = Cerapoda
infraordo = Ceratopsia
familia = Ceratopsidae
subfamilia = Ceratopsinae
genus = "Torosaurus"
genus_authority=Marsh, 1891
subdivision_ranks=Species
subdivision=
*"T. latus" Marsh, 1891 (type)

"Torosaurus" (meaning "perforated lizard") was a genus of ceratopsid dinosaur. It had one of the largest skulls of any land animal known, reaching 2.6 meters (8.5 ft) in length. From head to tail, "Torosaurus" probably measured about 7.6 meters (25 ft) long and weighed an estimated 4 to 6 tonnes (4.4 to 6.6 tons).

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" Taxobox authority | author = Marsh | date = 1891 (type species)

Misassignments:
*"T. gladius" Taxobox authority | author = Marsh | date = 1891 (="T. latus")
*"T. utahensis" Taxobox authority | author = Lawson| date = 1976 (="T. latus")

(NB: The last species was originally described as "Arrhinoceratops utahensis" by Gilmore in 1946. Review by Sullivan "et al". in 2005 [Sullivan, R. M., A. C. Boere, and S. G. Lucas. 2005. Redescription of the ceratopsid dinosaur "Torosaurus utahensis" (Gilmore, 1946) and a revision of the genus. "Journal of Paleontology" 79:564-582.] 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). [Dodson, P. (1996). "The Horned Dinosaurs". Princeton University Press, Pinceton, New Jersey, pp. xiv-346] 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". [Farke, A. A. 2006. Cranial osteology and phylogenetic relationships of the chasmosaurine ceratopsid "Torosaurus latus"; pp. 235-257 in K. Carpenter (ed.), "Horns and Beaks: Ceratopsian and Ornithopod Dinosaurs". Indiana University Press, Bloomington.] 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".
* Torosaurus was featured in Vivendi's ""
* "Torosaurus" is a nickname for Ray Toro, one of the guitarists in the band My Chemical Romance.

References

* Dodson, P. (1996). "The Horned Dinosaurs". Princeton University Press, Princeton, New Jersey, pp. xiv-346
* Haines, Tim & Chambers, Paul. (2006)The Complete Guide to Prehistoric Life. Canada: Firefly Books Ltd.

External links

* http://www.dinosaurvalley.com/Visiting_Drumheller/Kids_Zone/Groups_of_Dinosaurs/index.php
* http://www.dinosaurier-web.de/galery/pages_t/torosaurus.html