Saturday 19 March 2016

Torosaurus latus: A new specimen from the End Cretaceous Hell Creek Formation of Montana.

Torosaurus latus is a  Chasmosaurine Ceratopsid Dinosaur known from End Cretaceous deposits in the northwest United States and western Canada. To date eight (or possibly) nine specimens have been described, two or three (one specimen is only tentatively assigned to the species) from the Lance Formation of Wyoming, three from the Hell Creek Formation in Montana, two from the Hell Creek Formation in Montana and one from the Frenchman formation of Saskatchewan. The species is roughly contemporary with Triceratops horridus, both in temporal and geographical range, though it is larger and less abundant. In 2010 it was suggested that Torosaurus might in fact be the mature form of Triceratops, which has led to an ongoing debate among specialists in the field as to whether the fossils represent one or two species. As yet no immature specimens clearly of Torosaurus have been discovered, and the debate remains unresolved.

In a paper published in the journal PLoS One on 14 March 2016, Andrew McDonald of the Saint Louis Science Center, Carl Campbell of the St. Louis Community College-Meramec and Brian Thomas, also of the Saint Louis Science Center describe a new specimen of Torosaurus latus from the Hell Creek Formation in Montana.

The specimen comprises a partial pariatal bone, a skull bone which forms part of the rim of the crest in Ceratopsids. Most of the left of the bone is present, though it is broken close to the contact with the squamosal (cheek) bone.

Parietal of Torosaurus latus in dorsal view. Abbreviations: ep1, epiparietal locus 1; ep2, epiparietal locus 2; ep3, epiparietal locus 3; ep4, epiparietal locus 4; ep5, epiparietal locus 5; ep6, epiparietal locus 6; lpf, left parietal fenestra; mdr, midline ridge; rpf, rim of right parietal fenestra. Scale bar equals 10 cm. McDonald et al. (2016).

Assessing the age of a Dinosaur from a single fragmentary bone is problematic, but the new Hell Creek Torosaurus specimen is well vascuralized, and appears to have a general texture consistent with a mature individual, so McDonald et al.  conclude that the specimen was almost certainly an adult, and therefore cannot usefully be used to shed any light on the ongoing Torosaurus/Triceratops debate.

See also... wucaiwanensis: A new species of Ceratopsid Dinosaur from the Late Jurassic of Xinjiang Province, China.  Ceratopsid Dinosaurs are one of the most diverse and specious groups of herbivorous Ornithischian Dinosaurs, with a large...
Regaliceratops peterhewsi: A new species of Chasmosaur from the Late Cretaceous of Alberta.                                                                         Ceratopsids are among the most distinctive and...Regaliceratops peterhewsi: A new species of Chasmosaur from the Late Cretaceous of Alberta.                                                                         Ceratopsids are among the most distinctive and...
Ceratopsian Dinosaurs are thought to have originated in Asia in the Early Cretaceous, spreading to Europe and North America, and becoming the most important and diverse group of herbivorous Dinosaurs in North America by the end of the Period. Unfortunately...
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