Dedicated to summarizing the facts regarding origins
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Thescelosaurus Skeleton
Rocky Mountain Dinosaur Resource Center, Woodland Park, Colorado
Photo by J. Spenser[6]
Thescelosaurus
Thescelosauruses were bipedal ornithopods with stout legs, short arms and long tails to counterbalance their bodies. Their tails were about half as long as the animals overall length. Each leg had four toes and each arm five very small fingers. Their chest and abdomen were broad and bulky.
Thescelosaurus Skull
Left: Skull of NCSM 15728 in right lateral view. (A) diagram highlighting the contacts between the bones on the right side of skull; (B) illustration of right side of skull; (C) photograph of right side of skull. In (A) and (B), grey regions indicate the presence of matrix on the specimen. Abbreviations: an, angular; asor, accessory supraorbital; bo, basioccipital; de, dentary; eo, fused opisthotic/exoccipital; fr, frontal; ju, jugal; la, lacrimal; mx, maxilla; na, nasal; pd, predentary; pf, prefrontal; pm, premaxilla; po, postorbital; pop, paroccipital process; qj, quadratojugal; qu, quadrate; sor, supraorbital; sq, squamosal; su, surangular. Scale bars equal 10 cm.
Clint A. Boyd [8]
Heads of Thescelosauruses were unusually long and tapered down from the back of the skull to the end of the snout which was tipped with a beak on the upper maxilla for snipping food. Teeth were very small for this animal's size. Six pairs of premaxillary teeth were present with no corresponding teeth on the lower jaw (mandible). These teeth were pointed and had a bulb shape towards the jaw. Between the premaxillary teeth and the maxillary teeth was a gap. The maxillary teeth consisted of about twenty sets and they and the corresponding teeth on the lower jaw were leaf shaped with fine ridges and very similar to those of Pachycephalosaurus. Thescelosauruses are generally thought to be herbivores because of their leaf-shaped teeth that are ideal for slicing up soft vegetation although they may have had a more varied diet. They had long bony rods over their eyes. [7]
Based on the limited number of Thescelosaurus fossils available to date, their overall length by most references varied from about 8 to 13 feet. Another source indicates to 15 feet.[2] Variations in adult sizes may be due to sexual dimorphism and/or perhaps adult age differences as most if not all reptiles today have the potential for growth their whole lives.
One specimen known as Willy was thought by some to have a four chambered heart. based on some material found in the chest area of its fossil skeleton. This lent weight to the question whether dinosaurs were cold-blooded or warm-blooded animals as birds and mammals are warm-blooded and have four chambered hearts. Later extensive testing showed that this material was only hardened sand that was probably washed in.[3]
There currently three generally recognized species of Thescelosauruses: T. neglectus, T garbanii, and T. assiniboiensis. [4] Also, Bugenasaura, a former named genus, has been been found to be a synonym for Thescelosaurus.
Thescelosaurus' fossils have been been found in Alberta and Saskatchewan, Canada; and Montana, Wyoming, South Dakota, and Colorado, USA. [5]
[2]
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[1] Dropzink [CC BY-SA 2.5 (https://creativecommons.org/licenses/by-sa/2.5)]
[2] Thescelosaurus, Prehistoric Wildlife, http//www.prehistoric-wildlife.com/species/t/thescelosaurus.html

[3] Cleland, Timothy P., Stoskopf, Michael K., Schweitzer, Mary H., Histological, chemical, and morphological reexamination of the “heart” of a small Late Cretaceous Thescelosaurus, https://link.springer.com/article/10.1007/s00114-010-0760-1 

[4]Thescelosaurus, Wikipedia,https://en.wikipedia.org/wiki/Thescelosaurus 

[5] Ibid.

[6] User:J. Spencer [GFDL (http://www.gnu.org/copyleft/fdl.html), CC-BY-SA-3.0 (http://creativecommons.org/licenses/by-sa/3.0/) or CC BY 2.5 (https://creativecommons.org/licenses/by/2.5)], from Wikimedia Commons
[7] Thescelosaurus: DinoChecker dinosaur archive, http://www.dinochecker.com/dinosaurs/THESCELOSAURUS
[8] Clint A. Boyd [CC BY 4.0 (https://creativecommons.org/licenses/by/4.0)]
[9] D. Gordon E. Robertson [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]

[10]Thescelosaurus, Prehistoric Wildlife, http//www.prehistoric-wildlife.com/species/t/thescelosaurus.html
[11] Tim Evanson from Washington, D.C., United States of America [CC BY-SA 2.0 (https://creative commons.org/licenses/by-sa/2.0)], via Wikimedia Commons

[12] Thescelosaurus, Dinopedia, https://dinopedia.fandom.com/wiki/Thescelosaurus   
Copyright 2019 All rights reserved.
Right: Skull of NCSM 15728 in left lateral view. (A) diagram highlighting the contacts between the bones on the left side of skull; (B) illustration of left side of skull; (C) photograph of left side of skull. In (A) and (B), grey regions indicate the presence of matrix on the specimen. Abbreviations: an, angular; bo, basioccipital; de, dentary; eo, fused opisthotic/exoccipital; fr, frontal; ju, jugal; la, lacrimal; mx, maxilla; na, nasal; par, parietal; pd, predentary; pf, prefrontal; pl, palatine; pm, premaxilla; po, postorbital; pop, paroccipital process; pro, prootic; ps, parasphenoid; pt, pterygoid; qu, quadrate; so, supraoccipital; sp, sclerotic plate; sq, squamosal; st, stapes; su, surangular. Scale bars equal 10 cm.
Thescelosaurus Skeleton
Thescelosaurus neglectus
Canadian Museum of Nature, Ottawa, Ontario, Canada
Cast of NMC 8537, type specimen of T. edmontonensis (T. sp. per Boyd et al., [2009]
Photo by D. Gordon E. Robertson[9]
Vertebra (fossil)
1989 Fd. Hell Creek Formation, Carter Co., Montana, USA
Found in the same micro-site as 1990 and 1991
2.8" high max. Specimen's lateral processes 2.85" tip to tip
Premaxillary Tooth (fossil)
Considerable tip wear with some fine ridges still on base of crown.
2009 Fd. Hell Creek Formation, Montana, USA
0.35" long
Toe Ungual (cast)
2024 Fd. Hell Creek Formation, Harding Co., South Dakota, USA
1.35" long, 0.7" width max.
Mandible Body Portion (fossil)
Longitudinal section showing spacing of teeth sockets
1990 Fd. Hell Creek Formation, Carter Co., Montana, USA
1.5" long, 0.6" high max.
Phalanx (fossil)
1991 Fd. Hell Creek Formation,
Carter Co., Montana, USA
0.9" long, 0.8" width max.
Thescelosaurus Skeleton
Thescelosaurus neglectus
Museum of the Rockies, Bozeman, Montana, USA
Photo by Tim Evanson [11]
Thescelosaurus upper legs were longer than their lower legs. By this it has been interpreted that they were slow runners. [10] If they were slow runners, then how they avoided the various predators found in the same stratum such as Tyrannosaurus Rex is uncertain. Shorter legs may provide some advantage over longer legs running up steep slopes as river banks or mountains. Also, it has been suggested that they avoided predators by swimming to the other side of rivers.
Fd. Dawson Co., Montana
In popular culture it is not uncommon to seeThescelosauruses depicted as having feathers. There is no evidence so far to support this assumption (guess).[12]