|Species|| T. latus|
Torosaurus was discovered by paleontologists in southeastern Wyoming in 1891, and were identified and named by Othniel Charles Marsh. He apparently named it "bull lizard" after the bull-like appearance of the head; however, others have conjectured that the name instead should be interpreted to mean "pierced" or "perforated", after the large openings in the frill.
Torosaurus was the largest ceratopsian, up to 30 feet long with an estimated weight in excess of 6 tons. The forelimbs were shorter than the hindlimbs, yet current measurements indicate Torosaurus was able to trot and charge much like a modern rhinoceros despite its bulk. The skull was nearly a third of the entire animal's length; at eight feet long it is one of the largest skulls on record from a terrestrial animal. There were three horns, one over each eye and a smaller one on the snout. A frill extended from the back of the skull over the animal's neck to near the shoulders, giving some protection for that area from predators, as well as serving as an anchor for powerful neck muscles. The frill itself bore what has been called the fenestræ, or "windows", large openings within the bone which may have been overlaid by skin.
The mouth was beaked at the fore, leading scientists to speculate that it fed by "nipping" vegetation rather than grazing; the food was then ground down by a battery of simple, yet effective, cheek teeth. They were assumed to have been browsers of low-lying plants.
Paleontologists once believed there were several species of Torosaurus, judging from the large number of fossil remains, but it is now thought that there were just two, T. latus and T. utahensis; a third species (T. gladius) was investigated and found to have been a is-assigned name applied to T. latus. According to evolution, they are descended from Psittacosaurus, a small bipedal ornithopod whose remains were found in central Asia, and from there the ceratopsian line migrated to North America.
There has been a recent claim that Torosaurus may be Triceratops, albeit fully mature. According to the Journal of Vertebrate Paleontology, scientists theorize that ceratopsian dinosaurs, like all reptiles, continued to grow with age; this growth included changes to the frill which - according to the theory - changed from the deeply-curved solid bone of Tricertops into the "straight-backed" frill of Torosaurus, a change of which also involved a loss of bone creating the fenestræ as a result. According to Dr. Jack Horner, this process involved "metaplastic" bone which caused a change in the shape of the skull as the animal aged, i.e. the backward pointing horns of a baby Triceratops turning into the forward pointing horns of an adult.
Creationists hold that Torosaurus, along with other dinosaurs, were created during the sixth day of creation week, and did not survive the post-flood world. In support of the great flood catastrophe, all known ceratopsian fossils were found in sedimentary (water-laid) rock.
- The Complete Book of Dinosaurs, by Dougal Dixon, Anness Publishing, 2006