Information about Thescelosaurus
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Thescelosaurus (IPA: /ˌθɛskələˈsɔːɹəs/ or /ˌθɛsələˈsɔːɹəs/, from the Greek θεσκελο-/thescelo- meaning "godlike", "marvelous", or "wondrous" and σαυρος/saurus "lizard")[1] was a genus of small ornithopod dinosaur that appeared at the very end of the Late Cretaceous period in North America, and was a member of the last dinosaurian fauna before the Cretaceous-Tertiary extinction event around 65.5 million years ago. The preservation and completeness of many of its specimens indicate that it may have preferred to live near streams.
This bipedal ornithopod is known from several partial skeletons and skulls that indicate it grew to between 2.5 and 4.0 meters (8.2 to 13.1 feet) in length on average. It had sturdy hind limbs, small wide hands, a head with an elongate pointed snout, and possibly small armor scutes along the midline of the back. This genus of dinosaur is regarded as a specialized hypsilophodont and a herbivore. Several species have been suggested for this genus, but only one, T. neglectus, is currently recognized; the others have been given their own genera, or are believed to be the same as T. neglectus (although there may be more than one species represented by the various fossils classified as Thescelosaurus.)
The genus attracted media attention in 2000, when a specimen unearthed in 1993 in South Dakota was interpreted as including a fossilized heart. There was much discussion over whether the remains were actually of a heart. Many scientists now doubt the identification of the object and the implications of such an identification.
Description
Thescelosaurus was a heavily-built bipedal animal, probably herbivorous,[2] but possibly omnivorous.[3] It would have browsed in the first meter or so from the ground, feeding selectively,[2] with food held in the mouth by cheeks while chewing.[4] Aside from the long narrow beak, the skull also had teeth in the premaxilla, or upper beak (a primitive trait among ornithopods), and long rod-like bones called palpebrals over the eyes, giving it heavy bony eyebrows.[5] Its teeth were of two types: small pointed premaxillary teeth, and leaf-shaped cheek teeth.[6] The exact number of teeth is unknown, as complete jaws have not been described.It had short, broad, five-fingered hands, four-toed feet with hoof-like toe tips, and a long tail braced by ossified tendons from the middle back to the tip, which would have reduced the flexibility of the tail.[7] The rib cage was broad, giving it a wide back, and the limbs were robust.[6] This animal may have been able to move on all fours, given its fairly long arms and wide hands,[4] but this idea has not been followed up in the scientific literature (although it does appear in popular works).[8][9] Charles M. Sternberg reconstructed it with the upper arm sticking out almost perpendicular to the body, another idea that has gone by the wayside. Thescelosaurus was probably slower than other hypsilophodonts, because of its heavier build and leg structure. Compared to them, it had unusual hindlimbs, because the upper leg is longer than the shin, the opposite of Hypsilophodon and running animals in general.[6] One specimen is known to have had a bone pathology, with the long bones of the right foot fused at their tops, hindering swift movement.[10]
)
Head and arms of Thescelosaurus.
Large thin flat bony plates similar to those in Talenkauen have been found next to the ribs' sides.[11] Their function is unknown; they may have played a role in respiration.[12] The nature of this species' integument, be it scales or something else, is currently unknown, although potential evidence is known; Charles Gilmore described patches of carbonized material near the shoulders as possible epidermis, with a "punctured" texture but no regular pattern,[7] and William J. Morris suggested that armor was present, in the form of small scutes present at least along the midline of the neck.[13]
Overall, the skeletal anatomy of this genus is well-documented (except for the head), and restorations have been published in several papers, including skeletal restorations[7][4][14] and models.[7][6] The skeleton is known well enough that a detailed reconstruction of the hip and hindlimb muscles has been made.[15] The animal's size has been estimated in the 2.5–4.0 m range for length (8.2–13.1 ft)[4] for various specimens, and a weight of 200–300 kilograms (450–660 pounds).[16] As discussed more fully under "Discovery, history, and species", it may have been sexually dimorphic, with one sex larger than the other.[4] Juvenile remains are known from several locations, mostly based on teeth.[17][18]
Classification
Thescelosaurus has generally been allied to Hypsilophodon and other small ornithopods as a hypsilophodontid, although recognized as being distinct among them for its robust build, unusual hindlimbs, and, more recently, its unusually long skull.[6][4][19][2] Peter Galton in 1974 presented one twist to the classic arrangement, suggesting that because of its hindlimb structure and heavy build (not cursorial, or built for running, by his definition), it should be included in the Iguanodontidae. This has not been followed, with Morris arguing strongly against Galton's classification scheme.[13] At any rate, Galton's Iguanodontidae was not a natural group due to polyphyly, and so would not be recognized under modern cladistic usage.Although little tested by cladistics, it is currently thought that Bugenasaura and Thescelosaurus are closely related,[20] or that Thescelosaurus belongs in its own family or subfamily, Thescelosauridae or Thescelosaurinae.[21][22][18] Two recent studies have found it to be a close relative of Parksosaurus, although neither named a specific clade, and one of the studies (Norman et al., 2004) is difficult to interpret because it did not include Iguanodontia in its diagrams.[23][2] This area of the dinosaur family tree is complicated by a lack of research, with some papers finding Hypsilophodontidae to be a natural group,[19][24] and others finding it to be a unnatural family leading into Iguanodontia (paraphyly).[23][2][25] The "natural group" hypothesis has been falling out of favor since the mid to late 1990s, and thus a paraphyletic Hypsilophodontidae is shown here. Oddly, Thescelosaurus has been regarded as both very basal[24] and very derived among the hypsilophodonts.[2] One issue specifically concerning Thescelosaurus is that not all of the remains assigned to T. neglectus necessarily belong to it.[26]
Cladogram
| Euornithopoda |
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This cladogram is based on Norman et al. (2004),[2] with the results of the very similar cladogram from Weishampel et al. (2003)[23] used to clarify the position of Iguanodontia, which was left out of Norman et al. The group consisting of Bugenasaura, Parksosaurus, and Thescelosaurus is roughly what modern informal usage of Thescelosaurinae corresponds to.
Discovery, history, and species
The type specimen of Thescelosaurus (USNM 7757) was discovered in 1891 by paleontologists John Bell Hatcher and William H. Utterback, from beds of the late Maastrichtian-age Upper Cretaceous Lance Formation of Niobrara County, Wyoming, USA. The skeleton, however, remained in its shipping crates for years until Charles W. Gilmore of the Smithsonian Institution' National Museum of Natural History had it prepared and described it in a short paper in 1913, naming it T. neglectus (neglectus: "neglected"). At the time, he thought it was related to Camptosaurus.[27] He provided a detailed monograph in 1915, describing the well-preserved skeleton. The type specimen was found largely in natural articulation and was missing only the head and neck, which were lost due to erosion.[7] The name comes from the surprise Gilmore felt at finding such a good specimen that had been unattended to for so long. He considered it to be a light, agile creature, and assigned it to the Hypsilophodontidae, a family of small bipedal dinosaurs.[7])
Charles Gilmore's 1915 reconstruction of Thescelosaurus.
Other remains of similar animals were found throughout the late 1800s and 1900s, although they didn't receive much attention. Another well-preserved skeleton from the slightly older Horseshoe Canyon Formation, in Alberta, Canada, was named T. warreni by William Parks in 1926.[28] This skeleton had notable differences from T. neglectus, and so Charles M. Sternberg placed it in a new genus, Parksosaurus, in 1937.[29] Sternberg also named an additional species, T. edmontonensis, based on another articulated skeleton, this time including a partial skull (NMC 8537), and drew attention to the genus' heavy build and thick bones; due to these differences from the regular light hypsilophodont build, he suggested that the genus warranted its own subfamily, Thescelosaurinae.[6] T. edmontonensis has, since Peter Galton's 1974 review, generally been considered a more robust individual (possibly the opposite sex of the type individual)[4] of T. neglectus.[19][2] The only sticking point has been the ankle of T. edmontonensis, which Galton claimed was damaged and misinterpreted, but which was accepted by William J. Morris (1976) as truly different from T. neglectus.[13]
In his paper, Morris described a partial skull with heavy ridges on the lower jaw and cheek (SDSM 7210) as an unidentified species of Thescelosaurus, from the late Maastrichtian-age Hell Creek Formation of Harding County, South Dakota, USA.[13] This skull was recognized as an unnamed hypsilophodont for many years,[19] until Galton assigned it the name Bugenasaura infernalis.[30] Morris also named a new species, on the basis of vertebrae and limb remains (LACM 33542) from the Hell Creek Formation of Garfield County, Montana, USA: T. garbanii. T. garbanii would have been about 4.5 m long (15 feet), larger than average specimens of T. neglectus. Because Morris believed that the ankles of T. garbanii compared favorably to those of T. edmontonensis, he assigned it to Thescelosaurus.[13] However, the scientific literature has favored Galton's view that T. edmontonensis was not different from T. neglectus (see above). To better accommodate this species, Galton in 1995 suggested that it belonged to his new genus Bugenasaura as B. garbanii (although noting that it could also be a leg of the similarly sized pachycephalosaurid Stygimoloch). As a result, only one valid species of Thescelosaurus is currently recognized: T. neglectus.[30] More study, though, could again split the known material into two or more species.[26]
Paleoecology
Temporal and geographic range
True Thescelosaurus remains are known definitely only from late Maastrichtian-age rocks, from Alberta (Scollard Formation) and Saskatchewan (Frenchman Formation), Canada, and Wyoming (Lance Formation), South Dakota (Hell Creek Formation), Montana (Hell Creek), and Colorado (Laramie Formation), USA.[2] With the exception of birds, it was one of the last extant genera of dinosaurs, its remains being found as close as 3 meters to the boundary clay containing the iridium layer that closes the Cretaceous.[31] There are reports of teeth from older, Campanian-age rocks, particularly from the Dinosaur Park Formation of Alberta,[32] but these specimens are not from Thescelosaurus and are much more likely those of Orodromeus.[30] More specimens are known than have been officially described for this genus, such as "Willo", with its complete skull, and the Triebold specimen,[3] which has been the source of several skeletal casts for museums.Habitat
Conflicting reports have been made as to its preferred habitat; one paper suggests it preferred channels to floodplains,[33] but another suggests it preferred the opposite.[22] No bonebeds or accumulations of multiple individuals have yet been reported. Dale Russell, in a popular work, noted that Thescelosaurus was the most common small herbivore in the Hell Creek Formation of the Fort Peck area. He described the environment of the time as a flat floodplain, with a relatively dry subtropical climate that supported a variety of plants ranging from angiosperm trees, to cedar and bald cypress, to ferns and gingkos. Although most dinosaur skeletons from this area are incomplete, possibly due to the low preservation potential of forests, Thescelosaurus skeletons are much more complete, suggesting that this genus frequented stream channels; thus when a Thescelosaurus died, it may have been in or near a river, making it easier to bury and preserve for later fossilization. Russell tentatively compared it to the capybaras and tapirs.[34] Other dinosaurs that shared its time and place include Bugenasaura, the ceratopsids Triceratops and Torosaurus, hadrosaurids Edmontosaurus and Anatotitan, ankylosaurid Ankylosaurus, pachycephalosaurians Pachycephalosaurus and Stygimoloch, and the theropods Ornithomimus, Troodon, and Tyrannosaurus.[35][36]Paleobiology
"Heart of stone"
In 2000, a skeleton of this genus informally known as "Willo", now on display at the North Carolina Museum of Natural Sciences, was described as including the remnants of a four-chambered heart and an aorta. It had been originally unearthed in 1993 in northwestern South Dakota. The authors had found the internal detail through computed tomography imagery. They suggested that the heart had been saponified (turned to grave wax) under airless burial conditions, and then changed to goethite, an iron mineral, by replacement of the original material. The authors interpreted the structure of the heart as indicating an elevated metabolic rate for Thescelosaurus, not reptilian cold-bloodedness.[11])
The possible heart of "Willo" (center).
Their conclusions have been disputed; other researchers published a paper where they assert that the heart is really a concretion. As they note, the anatomy given for the object is incorrect (for example, the "aorta" narrows coming into the "heart" and lacks arteries coming from it), it partially engulfs one of the ribs and has an internal structure of concentric layers in some places, and another concretion is preserved behind the right leg.[37] The original authors defended their position; they agreed that it was a type of concretion, but one that had formed around and partially preserved the more muscular portions of the heart and aorta.[38] The question of how this find reflects on metabolic rate and dinosaur internal anatomy may be moot, though, regardless of the object's identity. Both modern crocodilians and birds, the closest living relatives of dinosaurs, have four-chambered hearts (albeit modified in crocodilians), so dinosaurs probably had them as well; the structure is not necessarily tied to metabolic rate.[39]
In popular culture
)
The low build and short legs of Thescelosaurus may have given it a small turning radius.
Despite its reputation among professionals for lacking speed and agility,[6][4] Thescelosaurus has been a featured animal in a mathematical modeling problem given to undergraduate students, based around the question of what the best hunting strategy is for one or two pursuing Velociraptor hunting a Thescelosaurus which, due to its bony structure, has a much shorter turning radius.[42][43]
References
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2. ^ Norman, David B.; Sues, Hans-Dieter; Witmer, Larry M.; and Coria, Rodolfo A. (2004). "Basal Ornithopoda", in Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press, 393–412. ISBN 0-520-24209-2.
3. ^ Triebold Paleontology, Inc.. Thescelosaurus. Retrieved on 2007-01-26.
4. ^ Galton, Peter M. (1974). "Notes on Thescelosaurus, a conservative ornithopod dinosaur from the Upper Cretaceous of North America, with comments on ornithopod classification". Journal of Paleontology 48 (5): 1048–1067.
5. ^ Galton, Peter M. (1997). "Cranial anatomy of the basal hypsilophodontid dinosaur Thescelosaurus neglectus Gilmore (Ornithischia; Ornithopoda) from the Upper Cretaceous of North America". Revue Paléobiologie, Genève 16 (1): 231–258.
6. ^ Sternberg, Charles M. (1940). "Thescelosaurus edmontonensis, n. sp., and classification of the Hypsilophodontidae". Journal of Paleontology 14 (5): 481–494.
7. ^ Gilmore, Charles W. (1915). "Osteology of Thescelosaurus, an orthopodus dinosaur from the Lance Formation of Wyoming". Proceedings of the U.S. National Museum 49 (2127): 591–616.
8. ^ Lambert, David; and the Diagram Group (1990). "Thescelosaurids", The Dinosaur Data Book. New York: Avon Books, p. 153. ISBN 0-380-75896-3.
9. ^ Lessem, Donald; and Glut, Donald F. (1993). The Dinosaur Society Dinosaur Encyclopedia. Random House, Inc., p. 475. ISBN 0-679-41770-2.
10. ^ Erickson, Bruce R. (2003). Dinosaurs of the Science Museum of Minnesota. St. Paul, Minnesota: The Science Museum of Minnesota, 31–32. ISBN 911338-54-3.
11. ^ Fisher, Paul E.; Russell, Dale A.; Stoskopf, Michael K.; Barrick, Reese E.; Hammer, Michael; and Kuzmitz, Aandrew A. (April 2000). "Cardiovascular evidence for an intermediate or higher metabolic rate in an ornithischian dinosaur". Science 288 (5465): 503–505. DOI:10.1126/science.288.5465.503. Retrieved on 2007-03-10.
12. ^ Novas, Fernando E.; Cambiaso, Andrea V; and Ambrioso, Alfredo (2004). "A new basal iguanodontian (Dinosauria, Ornithischia) from the Upper Cretaceous of Patagonia". Ameghiniana 41 (1): 75–82.
13. ^ Morris, William J. (1976). "Hypsilophodont dinosaurs: a new species and comments on their systematics", in Churcher, C.S. (ed.): Athlon. Toronto: Royal Ontario Museum, 93–113. ISBN 0888541570.
14. ^ Brett-Surman, Michael K. (1997). "Ornithopods", in Farlow, James O.; and Brett-Surman, Michael K. (eds.): The Complete Dinosaur. Bloomington and Indianapolis: Indiana University Press, 330–346. ISBN 0-253-33349-0.
15. ^ Romer, Alfred S. (1927). "The pelvic musculature of ornithischian dinosaurs". Acta Zoologica 8: 225–275.
16. ^ Erickson, Bruce R. (2003). Dinosaurs of the Science Museum of Minnesota. St. Paul, Minnesota: The Science Museum of Minnesota, p. 31. ISBN 911338-54-3.
17. ^ Carpenter, Kenneth (1982). "[https://scientists.dmns.org/sites/kencarpenter/PDFs%20of%20publications/baby%20teeth.pdf Baby dinosaurs from the Late Cretaceous Lance and Hell Creek formations and a description of a new species of theropod]". Contributions to Geology 20 (2): 123–134. Retrieved on 2007-03-10.
18. ^ Russell, Dale A.; and Manabe, Makoto (2002). "Synopsis of the Hell Creek (uppermost Cretaceous) dinosaur assemblage", in Hartman, Joseph H.; Johnson, Kirk R.; and Nichols, Douglas J. (eds.): The Hell Creek Formation and the Cretaceous-Tertiary Boundary in the Northern Great Plains: An Integrated Continental Record of the End of the Cretaceous, Geological Society of America Special Paper, 361. Boulder, Colorado: Geological Society of America, 169–176. ISBN 0-8137-2361-2.
19. ^ Sues, Hans-Dieter; and Norman, David B. (1990). "Hypsilophodontidae, Tenontosaurus, Dryosauridae", in Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 1st, Berkeley: University of California Press, 498–509. ISBN 0-520-06727-4.
20. ^ Galton, Peter M. (1999). "Cranial anatomy of the hypsilophodont dinosaur Bugenasaura infernalis (Ornithischia: Ornithopoda) from the Upper Cretaceous of North America". Revue Paléobiologie, Genève 18 (2): 517–534.
21. ^ Holtz, Thomas R., Jr. (2000). "Classification and Evolution of the Dinosaur Groups", in Paul, Gregory S. (ed.): The Scientific American Book of Dinosaurs. New York: St. Martin's Press, 140–168. ISBN 0-312-26226-4.
22. ^ Carpenter, Kenneth; and Young, D. Bruce (2002). "[https://scientists.dmns.org/sites/kencarpenter/PDFs%20of%20publications/Denver%20dinos.pdf Late Cretaceous dinosaurs from the Denver Basin, Colorado]". Rocky Mountain Geology 37 (2): 237–254. Retrieved on 2007-03-10.
23. ^ Weishampel, David B.; Jianu, Coralia-Maria; Csiki, Z.; and Norman, David B. (2003). "Osteology and phylogeny of Zalmoxes (n.g.), an unusual euornithopod dinosaur from the latest Cretaceous of Romania". Journal of Systematic Palaeontology 1 (2): 1–56. DOI:10.1017/S1477201903001032.
24. ^ Weishamepel, David B.; and Heinrich, Ronald E. (1992). "Systematics of Hypsilophodontidae and Basal Iguanodontia (Dinosauria: Ornithopoda)". Historical Biology 6: 159–184. Retrieved on 2007-03-10.
25. ^ Varricchio, David J. (2007). "First trace and body fossil evidence of a burrowing, denning dinosaur". Proceedings of the Royal Society B: Biological Sciences online preprint. DOI:10.1098/rspb.2006.0443.
26. ^ Butler, Richard J.; Upchurch, Paul; and Norman, David B. (2007). "The phylogeny of the ornithischian dinosaurs". Journal of Systematic Palaeontology (published online).
27. ^ Gilmore, Charles W. (May 1913). "A new dinosaur from the Lance Formation of Wyoming". Smithsonian Miscellaneous Collections 61 (5): 1–5.
28. ^ Parks, William A (1926). "Thescelosaurus warreni, a new species of orthopodous dinosaur from the Edmonton Formation of Alberta". University of Toronto Studies (Geological Series) 21: 1–42.
29. ^ Sternberg, Charles M. (1937). "Classification of Thescelosaurus, with a description of a new species". Geological Society of America Proceedings for 1936: p. 365.
30. ^ Galton, Peter M. (1995). "The species of the basal hypsilophodontid dinosaur Thescelosaurus Gilmore (Ornithischia: Ornithopoda) from the Late Cretaceous of North America". Neues Jahrbuch fèur Geologie und Paläontologie Abhandlungen 198 (3): 297–311.
31. ^ Carpenter, Kenneth; Breithaupt, Brent H. (1986). "[https://scientists.dmns.org/sites/kencarpenter/PDFs%20of%20publications/NodoExtinct.pdf Latest Cretaceous occurrences of nodosaurid ankylosaurs (Dinosauria, Ornithischia) in Western North America and the gradual extinction of the dinosaurs]". Journal of Vertebrate Paleontology 6 (3): 251–257. Retrieved on 2007-03-10.
32. ^ Sahni, Ashok (1972). "The vertebrate fauna of the Judith River Formation, Montana" (free PDF, may not load). Bulletin of the American Museum of Natural History 147: 321–412. [1] Retrieved on 2007-03-10.
33. ^ Pearson, Dean A.; Schaefer, Terry; Johnson, Kirk R.; Nichols, Douglas J.; and Hunter, John P. (2002). "Vertebrate biostratigraphy of the Hell Creek Formation in southwestern North Dakota and northwestern South Dakota". The Hell Creek Formation and the Cretaceous-Tertiary Boundary in the Northern Great Plains: An Integrated Continental Record of the End of the Cretaceous. 145–167.
34. ^ Russell, Dale A. (1989). An Odyssey in Time: Dinosaurs of North America. Minocqua, Wisconsin: NorthWord Press, Inc., 175–176. ISBN 1-55971-038-1.
35. ^ Weishampel, David B.; Barrett, Paul M.; Coria, Rodolfo A.; Le Loeuff, Jean; Xu Xing; Zhao Xijin; Sahni, Ashok; Gomani, Elizabeth, M.P.; and Noto, Christopher R. (2004). "Dinosaur Distribution". The Dinosauria (2nd). 517–606.
36. ^ Phillip Bigelow. Cretaceous "Hell Creek Faunal Facies''; Late Maastrichtian. Retrieved on 2007-01-26.
37. ^ Rowe, Timothy; McBride, Earle F.; and Sereno, Paul C. (February 2001). "Technical comment: dinosaur with a heart of stone". Science 291 (5505): p. 783a. DOI:10.1126/science.291.5505.783a. Retrieved on 2007-03-10.
38. ^ Russell, Dale A.; Fisher, Paul E.; Barrick, Reese E.; and Stoskopf, Michael K. (February 2001). "Reply: dinosaur with a heart of stone". Science 291 (5505): p. 783a. DOI:10.1126/science.291.5505.783a. Retrieved on 2007-03-10.
39. ^ Chinsamy, Anusuya; and Hillenius, Willem J. (2004). "Physiology of nonavian dinosaurs". The Dinosauria, 2nd. 643–659.
40. ^ Lambert, David; and the Diagram Group (1983). "Thescelosaurids", A Field Guide to Dinosaurs. New York: Avon Books, p. 149. ISBN 0-380-83519-3.
41. ^ Dixon, Dougal (2006). The Complete Book of Dinosaurs. London: Anness Publishing Ltd., 212–213. ISBN 0-681-37578-7.
42. ^ Amrita Das. The Hunting Strategy of the Velociraptor — Amrita Das. Retrieved on 2007-01-26.
43. ^ John David Stone. Mathematical Contest in Modeling, 1997. Retrieved on 2007-01-29.
2. ^ Norman, David B.; Sues, Hans-Dieter; Witmer, Larry M.; and Coria, Rodolfo A. (2004). "Basal Ornithopoda", in Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 2nd, Berkeley: University of California Press, 393–412. ISBN 0-520-24209-2.
3. ^ Triebold Paleontology, Inc.. Thescelosaurus. Retrieved on 2007-01-26.
4. ^ Galton, Peter M. (1974). "Notes on Thescelosaurus, a conservative ornithopod dinosaur from the Upper Cretaceous of North America, with comments on ornithopod classification". Journal of Paleontology 48 (5): 1048–1067.
5. ^ Galton, Peter M. (1997). "Cranial anatomy of the basal hypsilophodontid dinosaur Thescelosaurus neglectus Gilmore (Ornithischia; Ornithopoda) from the Upper Cretaceous of North America". Revue Paléobiologie, Genève 16 (1): 231–258.
6. ^ Sternberg, Charles M. (1940). "Thescelosaurus edmontonensis, n. sp., and classification of the Hypsilophodontidae". Journal of Paleontology 14 (5): 481–494.
7. ^ Gilmore, Charles W. (1915). "Osteology of Thescelosaurus, an orthopodus dinosaur from the Lance Formation of Wyoming". Proceedings of the U.S. National Museum 49 (2127): 591–616.
8. ^ Lambert, David; and the Diagram Group (1990). "Thescelosaurids", The Dinosaur Data Book. New York: Avon Books, p. 153. ISBN 0-380-75896-3.
9. ^ Lessem, Donald; and Glut, Donald F. (1993). The Dinosaur Society Dinosaur Encyclopedia. Random House, Inc., p. 475. ISBN 0-679-41770-2.
10. ^ Erickson, Bruce R. (2003). Dinosaurs of the Science Museum of Minnesota. St. Paul, Minnesota: The Science Museum of Minnesota, 31–32. ISBN 911338-54-3.
11. ^ Fisher, Paul E.; Russell, Dale A.; Stoskopf, Michael K.; Barrick, Reese E.; Hammer, Michael; and Kuzmitz, Aandrew A. (April 2000). "Cardiovascular evidence for an intermediate or higher metabolic rate in an ornithischian dinosaur". Science 288 (5465): 503–505. DOI:10.1126/science.288.5465.503. Retrieved on 2007-03-10.
12. ^ Novas, Fernando E.; Cambiaso, Andrea V; and Ambrioso, Alfredo (2004). "A new basal iguanodontian (Dinosauria, Ornithischia) from the Upper Cretaceous of Patagonia". Ameghiniana 41 (1): 75–82.
13. ^ Morris, William J. (1976). "Hypsilophodont dinosaurs: a new species and comments on their systematics", in Churcher, C.S. (ed.): Athlon. Toronto: Royal Ontario Museum, 93–113. ISBN 0888541570.
14. ^ Brett-Surman, Michael K. (1997). "Ornithopods", in Farlow, James O.; and Brett-Surman, Michael K. (eds.): The Complete Dinosaur. Bloomington and Indianapolis: Indiana University Press, 330–346. ISBN 0-253-33349-0.
15. ^ Romer, Alfred S. (1927). "The pelvic musculature of ornithischian dinosaurs". Acta Zoologica 8: 225–275.
16. ^ Erickson, Bruce R. (2003). Dinosaurs of the Science Museum of Minnesota. St. Paul, Minnesota: The Science Museum of Minnesota, p. 31. ISBN 911338-54-3.
17. ^ Carpenter, Kenneth (1982). "[https://scientists.dmns.org/sites/kencarpenter/PDFs%20of%20publications/baby%20teeth.pdf Baby dinosaurs from the Late Cretaceous Lance and Hell Creek formations and a description of a new species of theropod]". Contributions to Geology 20 (2): 123–134. Retrieved on 2007-03-10.
18. ^ Russell, Dale A.; and Manabe, Makoto (2002). "Synopsis of the Hell Creek (uppermost Cretaceous) dinosaur assemblage", in Hartman, Joseph H.; Johnson, Kirk R.; and Nichols, Douglas J. (eds.): The Hell Creek Formation and the Cretaceous-Tertiary Boundary in the Northern Great Plains: An Integrated Continental Record of the End of the Cretaceous, Geological Society of America Special Paper, 361. Boulder, Colorado: Geological Society of America, 169–176. ISBN 0-8137-2361-2.
19. ^ Sues, Hans-Dieter; and Norman, David B. (1990). "Hypsilophodontidae, Tenontosaurus, Dryosauridae", in Weishampel, David B.; Dodson, Peter; and Osmólska, Halszka (eds.): The Dinosauria, 1st, Berkeley: University of California Press, 498–509. ISBN 0-520-06727-4.
20. ^ Galton, Peter M. (1999). "Cranial anatomy of the hypsilophodont dinosaur Bugenasaura infernalis (Ornithischia: Ornithopoda) from the Upper Cretaceous of North America". Revue Paléobiologie, Genève 18 (2): 517–534.
21. ^ Holtz, Thomas R., Jr. (2000). "Classification and Evolution of the Dinosaur Groups", in Paul, Gregory S. (ed.): The Scientific American Book of Dinosaurs. New York: St. Martin's Press, 140–168. ISBN 0-312-26226-4.
22. ^ Carpenter, Kenneth; and Young, D. Bruce (2002). "[https://scientists.dmns.org/sites/kencarpenter/PDFs%20of%20publications/Denver%20dinos.pdf Late Cretaceous dinosaurs from the Denver Basin, Colorado]". Rocky Mountain Geology 37 (2): 237–254. Retrieved on 2007-03-10.
23. ^ Weishampel, David B.; Jianu, Coralia-Maria; Csiki, Z.; and Norman, David B. (2003). "Osteology and phylogeny of Zalmoxes (n.g.), an unusual euornithopod dinosaur from the latest Cretaceous of Romania". Journal of Systematic Palaeontology 1 (2): 1–56. DOI:10.1017/S1477201903001032.
24. ^ Weishamepel, David B.; and Heinrich, Ronald E. (1992). "Systematics of Hypsilophodontidae and Basal Iguanodontia (Dinosauria: Ornithopoda)". Historical Biology 6: 159–184. Retrieved on 2007-03-10.
25. ^ Varricchio, David J. (2007). "First trace and body fossil evidence of a burrowing, denning dinosaur". Proceedings of the Royal Society B: Biological Sciences online preprint. DOI:10.1098/rspb.2006.0443.
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27. ^ Gilmore, Charles W. (May 1913). "A new dinosaur from the Lance Formation of Wyoming". Smithsonian Miscellaneous Collections 61 (5): 1–5.
28. ^ Parks, William A (1926). "Thescelosaurus warreni, a new species of orthopodous dinosaur from the Edmonton Formation of Alberta". University of Toronto Studies (Geological Series) 21: 1–42.
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30. ^ Galton, Peter M. (1995). "The species of the basal hypsilophodontid dinosaur Thescelosaurus Gilmore (Ornithischia: Ornithopoda) from the Late Cretaceous of North America". Neues Jahrbuch fèur Geologie und Paläontologie Abhandlungen 198 (3): 297–311.
31. ^ Carpenter, Kenneth; Breithaupt, Brent H. (1986). "[https://scientists.dmns.org/sites/kencarpenter/PDFs%20of%20publications/NodoExtinct.pdf Latest Cretaceous occurrences of nodosaurid ankylosaurs (Dinosauria, Ornithischia) in Western North America and the gradual extinction of the dinosaurs]". Journal of Vertebrate Paleontology 6 (3): 251–257. Retrieved on 2007-03-10.
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34. ^ Russell, Dale A. (1989). An Odyssey in Time: Dinosaurs of North America. Minocqua, Wisconsin: NorthWord Press, Inc., 175–176. ISBN 1-55971-038-1.
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36. ^ Phillip Bigelow. Cretaceous "Hell Creek Faunal Facies''; Late Maastrichtian. Retrieved on 2007-01-26.
37. ^ Rowe, Timothy; McBride, Earle F.; and Sereno, Paul C. (February 2001). "Technical comment: dinosaur with a heart of stone". Science 291 (5505): p. 783a. DOI:10.1126/science.291.5505.783a. Retrieved on 2007-03-10.
38. ^ Russell, Dale A.; Fisher, Paul E.; Barrick, Reese E.; and Stoskopf, Michael K. (February 2001). "Reply: dinosaur with a heart of stone". Science 291 (5505): p. 783a. DOI:10.1126/science.291.5505.783a. Retrieved on 2007-03-10.
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External links
- Willo, the Dinosaur with a Heart - The official site for "Willo", from the North Carolina Museum of Natural Sciences.
- Ornithopoda at the Thescelosaurus! site
- Thescelosaurus from Palaeos.com (Technical)
){kind=small}
Late Cretaceous (100mya - 65mya) refers to the second half of the Cretaceous Period, named after the famous white chalk cliffs of southern England, which date from this time. Rocks deposited during the Late Cretaceous Period are referred to as the Upper Cretaceous Series.
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Scientific classification or biological classification is a method by which biologists group and categorize species of organisms. Scientific classification also can be called scientific taxonomy, but should be distinguished from folk taxonomy, which lacks scientific basis.
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Chordata
Bateson, 1885
Typical Classes
See below
Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates.
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Bateson, 1885
Typical Classes
See below
Chordates (phylum Chordata) are a group of animals that includes the vertebrates, together with several closely related invertebrates.
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Sauropsida*
Goodrich, 1916
Subclasses
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Goodrich, 1916
Subclasses
- Anapsida
- Diapsida
- Reptilia Laurenti, 1768
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Dinosauria *
Owen, 1842
Orders & Suborders
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Owen, 1842
Orders & Suborders
- Ornithischia
- Cerapoda
- Thyreophora
- Saurischia
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Ornithischia
Seeley, 1888
Suborders
Ornithischia or Predentata is an order of beaked, herbivorous dinosaurs.
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Seeley, 1888
Suborders
- Cerapoda
- Thyreophora
Ornithischia or Predentata is an order of beaked, herbivorous dinosaurs.
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Cerapoda
Sereno, 1986
Infraorders
Cerapoda is a clade or suborder of the order Ornithischia. They are the sister group of the Thyreophora within the clade Genasauria.
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Sereno, 1986
Infraorders
- Ceratopsia
- Ornithopoda
- Pachycephalosauria
Cerapoda is a clade or suborder of the order Ornithischia. They are the sister group of the Thyreophora within the clade Genasauria.
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Ornithopoda
Marsh, 1881
Families
Ornithopods
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Marsh, 1881
Families
- Hypsilophodontidae*
- Rhabdodontidae
- Dryosauridae
- Camptosauridae
- Iguanodontidae
- Hadrosauridae
Ornithopods
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Hypsilophodontidae
Dollo, 1882
Genera
See text.
Hypsilophodonts (named after the Hypsilophus genus of iguana lizard, literally meaning "high-crested tooth") were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the
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Dollo, 1882
Genera
See text.
Hypsilophodonts (named after the Hypsilophus genus of iguana lizard, literally meaning "high-crested tooth") were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the
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Hypsilophodontidae
Dollo, 1882
Genera
See text.
Hypsilophodonts (named after the Hypsilophus genus of iguana lizard, literally meaning "high-crested tooth") were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the
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Dollo, 1882
Genera
See text.
Hypsilophodonts (named after the Hypsilophus genus of iguana lizard, literally meaning "high-crested tooth") were small ornithopod dinosaurs, regarded as fast, herbivorous bipeds on the
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Charles Whitney Gilmore (1874-1945) was an American paleontologist, who named dinosaurs in North America and Mongolia, including the Cretaceous sauropod Alamosaurus, Alectrosaurus, Archaeornithomimus, Bactrosaurus, Brachyceratops,
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species is one of the basic units of biological classification. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring.
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In biology, a type is that which fixes a name to a taxon. Depending on the nomenclature code which is applied to the organism in question, a type may be a specimen, culture, illustration, description or taxon.
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This chart shows concisely the most common way in which the International Phonetic Alphabet (IPA) is applied to represent the English language.
See International Phonetic Alphabet for English for a more complete version and Pronunciation respelling for English for phonetic
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See International Phonetic Alphabet for English for a more complete version and Pronunciation respelling for English for phonetic
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Ancient Greek refers to the second stage in the history of the Greek language[1] as it existed during the Archaic (9th–6th centuries BC) and Classical (5th–4th centuries BC) periods in Greece.
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Lacertilia*
Günther, 1867
Families
Many, see text.
Lizards are reptiles of the order Squamata, normally possessing four legs, external ear openings and movable eyelids.
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Günther, 1867
Families
Many, see text.
Lizards are reptiles of the order Squamata, normally possessing four legs, external ear openings and movable eyelids.
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genus (plural: genera) is part of the Latinized name for an organism. It is a name which reflects the classification of the organism by grouping it with other closely similar organisms.
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Ornithopoda
Marsh, 1881
Families
Ornithopods
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Marsh, 1881
Families
- Hypsilophodontidae*
- Rhabdodontidae
- Dryosauridae
- Camptosauridae
- Iguanodontidae
- Hadrosauridae
Ornithopods
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Dinosauria *
Owen, 1842
Orders & Suborders
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Owen, 1842
Orders & Suborders
- Ornithischia
- Cerapoda
- Thyreophora
- Saurischia
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Late Cretaceous (100mya - 65mya) refers to the second half of the Cretaceous Period, named after the famous white chalk cliffs of southern England, which date from this time. Rocks deposited during the Late Cretaceous Period are referred to as the Upper Cretaceous Series.
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A geologic period is a subdivision of geologic time that divides an era into smaller timeframes. The equivalent term used to demarcate rock layers and the fossil record is the system; thus the rocks of the Devonian System were laid down during the Devonian Period.
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North America is a continent [1] in the Earth's northern hemisphere and (chiefly) western hemisphere. It is bordered on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the southeast by the Caribbean Sea, and on the south and west
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Fauna is all of the animal life of any particular region or time. The corresponding term for plants is flora.
Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g.
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Zoologists and paleontologists use fauna to refer to a typical collection of animals found in a specific time or place, e.g.
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worldwide view.
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Bipedalism is standing, or moving for example by walking, running, or hopping, on two appendages (typically legs). An animal or machine that usually moves in a bipedal manner is known as a biped (/'baɪ.
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1 metre =
SI units
1000 mm 0 cm
US customary / Imperial units
0 ft 0 in
The metre or meter[1](symbol: m) is the fundamental unit of length in the International System of Units (SI).SI units
1000 mm 0 cm
US customary / Imperial units
0 ft 0 in
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1 foot =
SI units
0 m 0 mm
US customary / Imperial units
0 yd 0 in
A foot (plural: feet or foot;[1] symbol or abbreviation: ft or, sometimes, ′SI units
0 m 0 mm
US customary / Imperial units
0 yd 0 in
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Armour (or armor) in animals is external or superficial protection against attack by predators, formed as part of the body (rather than the behavioural use of protective external objects), usually through the hardening of body tissues, outgrowths or secretions.
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A scute or scutum (Latin scutum, plural: scuta "shield") is a horny, chitinous, or bony external plate or scale, as on the shell of a turtle or the skin of crocodiles.
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Herod_Archelaus
