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Titanotheres – Megacerops, Sphenocoelus, and Palaeosyops of North America

White River Formation
Restored from a skeleton in the American Museum of Natural History
Drawing of Skeleton[10]
(synonym Titanotherium robustum)
Megacerops,Sphenocoelus andPalaeosyops are classified as three genera of Titanotheres also called Brontotheres (Mammalia, Perissodactyla) that were endemic to parts of North America and became extinct a long time ago along with all other members of this family around the world. The titanotheres were herbivores and had unique upper teeth with a w-shaped ridge.[1] Attempts to relate these genera to various perissodactyla ancestors and descendents are wholly subjective. Variations within species, an evolutionary mindset and "subjective criteria" have led one past prominent paleotologist to "hypersplit" almost every titanothere bone found to a new species. The futility of splitting can be seen today most clearly in the domestic dog species (Canis familiaris)."The skull, body, and limb proportions vary significantly between breeds, with dogs displaying more phenotypic diversity than can be found within the entire order of carnivores." [2] Titanothere species may have been no less variable.
Sorting out of the scientific classifications of titanotheres in North America is very difficult. Synonyms for a genus abound withMegacerops having no less than six includingBrontops,Menodus andTitanotherium. The species ofMegacerops have been reduced to two based primarily on their horns; however, horns generally and specifically in this genus have been found to be quite variable so maybe there is just one.Palaeosyops vallidens has been reclassified asManteoceras, the name originally suggested .[3] The latter may also be a synonym forDolichorhinus.[4]Dolichorhinus heterodon is probably a synonym forSphenocoelus intermedius.[5]
Reasons for their extinction are subject to much speculation by evolutionists including environmental change and disease whereas creationists mainly point to Noah's flood.
Megacerops were very robust and grew to a height of about 8.2 feet at the shoulders and 14 feet long. Their estimated body weight based on one specimen was 3.6 short tons .[6] They had elongated skulls with shortened faces, small eyes towards the nostrils, ears near the back of the skull, and a bifurcated bony horn over the nasal region. The male’s horns are said to have been larger than those of females.
"(The) brain-case was enormously thick and yet lightened by an intricate system of communicating cavities or "sinuses," separated by many bony braces and supports connecting the inner and outer denser layers, which form the surfaces of the bones." Their brain cavity was about the size of a man's fist. [7]
Teeth were low crowned and adapted for eating non abrasive vegetation instead of grasses. The canines were much too small too serve as weapons.[8]
Legs were rather short for their body size but stout indicating that they most likely were relatively slow runners. They had four toes on each front leg and three toes on each hind leg. The toes were tipped with hooves and the weight on a leg was supported on a great pad.[9]
Fossils of Megacerops have been found in the White River Formation of northeastern Colorado, western Nebraska, southwestern South Dakota (Badlands), southeastern Wyoming, USA and in Saskatchewan, Canada.
Vertebra (fossil)
1427 Fd. Brule Formation, White River Badlands Group
Titanotheriium elatum
American Museum of Natural History
(Color added)
Titanothere Metatarsal
1376 Fd. Toadstool Area, Nebraska, USA
8.3" long
Photo by R. Weller/Cochise College
Skeleton (fossil)
Fd. White River Formation, Colorado, USA
Natural History Museum, Los Angeles, USA
Lower back right molar (fossil)
(missing roots)
2026 Fd. Southwestern South Dakota, USA
3.5" long, 1.6" max. width
Skull with Upper Teeth [12]
Inferior view
Fd. White River Formation, USA
State Museum of Prehistory in Halle/Saale,Germany
Outside view
Grinding view
Sphenocoelus intermedius
(synonym Mesatirhinus superior)
Bridger stage, Wyoming and Eastern Utah
Restored from a skeleton in the American Museum of Natural History
Right ManusDrawing[7]
White River
(Color added)
Palaeosyops, Sphenocoelus, Manteoceras and Dolichorhinnus
Palaeosysops,Sphenocoelus,Manteoceras andDolichorhinnus were much smaller thanMegacerops all being approximately the size of a modern tapir. The estimated weight ofSpenocoelus based on one sample specimen was about234 lbs.[15] UnlikeMegaceratops,Palaeosysops andSphenocoelus had no horns andManteoceras andDolichorhinnus only one small bone bump.[16] Their molars were low crowned suitable for cutting and grinding soft leafy vegetation but not abrasive grasses as a regular diet. Also, unlikeMegacerops “their canine teeth were as large as those of a bear and must have been effective weapons.”[17] LikeMegacerops they had four toes on each front leg and three toes on each back leg. Each toe had a hoof and the hooves served to carry the animals weight unlikeMegacerops.[18]
Their fossils are found in the Bridger Formation of southwestern Wyoming, and northeastern Utah, USA.
Titanothere Kneecap (fossil)
1801 Fd. Bridger stage, Lusk Co., Wyoming, 2.4" 2.4" long, 2" max. width, 1.2" max thickness
Skeleton (fossil) [21]
Palaeosyops paludosus
National Museum of Natural History, Smithsonian Institution, Washington, DC, USA
Copyright 2014, 2019 All rights reserved.
[1] Brontotheriidae, American Museum of Natural History,[2] Dog,
[3] Mader,Bryn, Zootaxa 1837, A species level revision of Bridgerian and Uintan brontotheres (Mammalia, Perissodactyla) exclusive of Palaeosyops, Auckland, New Zealand: Magnolia Press), 53
[4] Ibid.
[5] Ibid. 46
[6] Megacerops,
[7] Scott, William B., Horsfall, Bruce - illustrator, A History of Land Mammals in the Western Hemisphere (New York: The MacMillian Co., 1913), 311
[8] Ibid. 310
[9] Ibid. 312
Left : broad-skulled Manteoceras
Right: long-skulled Dolichorhinnus
From an original in the American Museum of Natural History
Right Upper Molar[22]
Right ManusDrawing[g]
(Color added)
[10] Lydekker, R., A Geographical History of Mammals (Cambridge: University Press, 1896), 171 [11] Scott, 309 [12] DagdaMor [CC BY-SA 4.0 (]
[11] Scott, 309
[12] DagdaMor [CC By-SA 4.0 (]
[13] Scott, 311
[14] Ibid. 318
[15] Sphenocoelus,
[16] Scott, 272
[17] Ibid. 314
[18] Ibid. 315
[19] Ibid. 314 
[20] Ibid. 271
[21] Daderot [public domain)
[22] Lydekker, 377
[23] Scott, 318
[24] Osborn,Henry, The Age of Mammals in Europe, Asia and North America (New York: The MacMillan Co., 1921), 139
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