Torosaurus
Torosaurus (meaning "pierced lizard") was a large, quadrupedal, plant-eating Ceratopsian dinosaur with three horns on its large head. Torosaurus hatched from eggs and may have lived in herds.
| Torosaurus Temporal range: Upper Cretaceous
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| Mounted Torosaurus in Milwaukee | |
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| Genus: | Torosaurus Marsh, 1891
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Torosaurus lived during the Upper Cretaceous, about 70–65 million years ago, in what is now western North America. It was similar to Triceratops. Some had thought that Triceratops was a younger form of Torosaurus.[1][2][3]
However, latest thinking is that the two are definitely different genera.[4] In 2011, 2012 and 2013, studies of external features of known specimens decided that shape and development differences mean the two genera are not synonyms. The main problems in the "one genus" idea are: [5][6][7]
- A lack of good transitional forms,
- The apparent existence of authentic Torosaurus subadults, different skull proportions independent of maturation
- The hole formation at an adult stage is not part of a normal ceratopsian growth sequence.
Torosaurus Media
Marsh's original illustrations of the skulls of T. latus and its synonym T. gladius
Restoration of T. latus
Mounted skeleton (MPM VP6841), Milwaukee
An adult Triceratops horridus (MOR 1122) skull collected in Fergus County, Montana, on display at the Museum of the Rockies in Bozeman, Montana. Note the heavily grooved horns above the eyes. DISCLAIMER: Note this is actually a skull of Torosaurus, but Museum of the Rockies curator, John R.
Restoration of T. utahensis
A mounted specimen of Triceratops, conventionally considered a distinct genus from Torosaurus
According to the "toromorph" hypothesis, Triceratops subadults (A, Triceratops prorsus holotype YPM 1822) would have gotten longer frills with holes as shown by B, Torosaurus latus specimen ANSP 15192
The end phase would have consisted of an enormously large and flat frill as exemplified by specimen YPM 1831 (A), its size shown by comparison to ANSP 15192 (B), an early adult
Specimen ANSP 15192 might, according to Longrich, be a young female adult
Scanella & Horner saw Nedoceratops as an ontogenetic transitional form between Triceratops and Torosaurus
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References
- ↑ Scannella J. and Horner J.R. 2010. "Torosaurus Marsh, 1891, is Triceratops Marsh, 1889 (Ceratopsidae: Chasmosaurinae): synonymy through ontogeny ." Journal of Vertebrate Paleontology, 30(4): 1157 - 1168.
- ↑ Switek, Brian. "New Study Says Torosaurus=Triceratops". Dinosaur Tracking. Smithsonian.com. Archived from the original on 13 November 2013. Retrieved 2 March 2011.
- ↑ Horner, Jack. TEDX Talks: "Shape-shifting Dinosaurs Archived 2014-02-16 at the Wayback Machine". Nov 2011. Accessed 20 Nov 2012.
- ↑ Bowdler, Neil 2012. BBC News Science & Environment. Triceratops and Torosaurus dinosaurs 'two species, not one' [1]
- ↑ Longrich N.R & Field D.J. 2012. Torosaurus is not Triceratops: ontogeny in chasmosaurine ceratopsids as a case study in dinosaur taxonomy. PLoS ONE 7 (2): e32623. [2]
- ↑ Farke A.A. 2011. Anatomy and taxonomic status of the chasmosaurine ceratopsid Nedoceratops hatcheri from the Upper Cretaceous Lance Formation of Wyoming, U.S.A. PLoS ONE 6 (1): e16196. [3]
- ↑ Maiorino L; Farke A.A. et al 2013. Is Torosaurus Triceratops? Geometric morphometric evidence of Late Maastrichtian Ceratopsid Dinosaurs. PLoS ONE 8(11): e81608. doi:10.1371/journal.pone.0081608