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Temporal range: Late Cretaceous, 66 Ma
Agathaumas sylvestris.jpg
Illustration of the vertebrae and sacrum
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Family: Ceratopsidae
Subfamily: Chasmosaurinae
Tribe: Triceratopsini
Genus: Agathaumas
Cope, 1872
A. sylvestris
Binomial name
Agathaumas sylvestris
Cope, 1872

Agathaumas (/æɡəˈθɔːməs/; "great wonder") is a dubious genus of a large ceratopsid dinosaur that lived in Wyoming during the Late Cretaceous (late Maastrichtian stage, 66 million years ago). The name comes from the Greek αγαν agan – "much" – and θαυμα thauma – "wonder". It is estimated to have been 9 metres (30 ft) long and weighed 6 tonnes (5.9 long tons; 6.6 short tons), and was seen as the largest land animal known at the time of its discovery.[1]

It was the first named ceratopsian, though relatively little is known about it. The original specimen consisted only of the animal's hip bones, hip vertebrae and ribs, and because these bones vary little between ceratopsid species, it is usually considered a nomen dubium. It is provisionally considered a synonym of Triceratops, but is difficult to compare to that genus because it is only known from postcranial remains.[1][2]


Original sketch of Agathaumas silvestris by E.D. Cope in 1890

The fossil remains of Agathaumas were first found in 1872 in southwestern Wyoming. They were discovered by Fielding Bradford Meek and Henry Martyn Bannister while they were looking for fossil shells in the Lance Formation near the Black Butte and Bitter Creek. Meek and Bannister were employed by Ferdinand Vandeveer Hayden's Geological Survey of the Territories, and notified paleontologist Edward Drinker Cope of the find. Cope himself searched the ridge near Black Butte and re-discovered Meek's site, finding huge bones protruding from the rocks near a coal vein. The bones were preserved in sand and clay sediments, packed with fossil sticks and leaves, indicating a heavily forested habitat. Later in 1872, Cope published a description and name for the animal, Agathaumas sylvestris, or "marvelous forest-dweller," in reference to its great size and the environment revealed in the same rocks as its bones.[3] Cope later (in 1873) described the skeleton as "the wreck of one of the princes among giants."[4]The name Agathaumas has been cited as an example of Cope's excitement with this discovery, which he considered, at the time, as the largest known land animal that had ever lived. Several years later, with the discovery of the giant sauropod dinosaurs of the Morrison Formation, it became clear to him that British forms as Cetiosaurus and Pelorosaurus were land animals.[1]

Cope and his team eventually recovered complete hip bones, sacral vertebrae, and several ribs from the animal. Since these were the first ceratopsian remains found, Cope was uncertain as to precisely what sort of dinosaur Agathaumas was (and for a time considered it a hadrosaur) until O. C. Marsh described Triceratops in 1889.[1]

In an 1889 paper, Cope suggested that Marsh's Ceratopsidae be renamed Agathaumidae, because of the paucity of Ceratops remains.[5]



  • Agathaumas sylvestris Cope, 1872; 16 vertebrae from the tail, sacrum and back, a partial Ilium and several ribs

Species previously referred to Agathaumas:

  • A. flabellatus (Marsh, 1889) Burkhardt 1892; included with Triceratops horridus.[6]
  • A. milo Cope, 1874; included with Thespesius occidentalis.
  • A. monoclonius (Breithaupt, 1994); nomen dubium included with Monoclonius sphenocerus.
  • A. mortuarius (Cope, 1874) Hay, 1901; nomen dubium included with Triceratops horridus.
  • A. prorsus (Marsh, 1890) Lydekker, 1893; included with Triceratops prorsus.
  • A. sphenocerus (Cope, 1890) Ballou 1897; nomen dubium included with Monoclonius sphenocerus.[7]

Unfortunately, the bones of the rear half of the animal found are not particularly diagnostic in ceratopsians and Agathaumas remains a nomen dubium. No other remains have been found in the area, but based on its size and age of the rocks, it probably was only a Triceratops.

Knight's restoration[edit]

Agathaumas sphenocerus by Charles R. Knight, 1897.

In 1897, artist Charles R. Knight painted Agathaumas for Cope. Knight based the painting on the partial skull of the species Agathaumas sphenocerus, which had a large nasal horn and small horns over the eyes.[8] This skull was originally referred to the genus Monoclonius and later to Styracosaurus.[9] The body was based on a more complete skeleton of the species Triceratops prorsus that had been described by O.C. Marsh. At the time, Monoclonius, Agathaumas, and Triceratops were all thought to be close relatives that differed mainly in the arrangement of the horns and the presence of openings in the frill.[8] This painting was later used as basis for a model Agathaumas in the 1925 film The Lost World.[10]

See also[edit]


  1. ^ a b c d Breithaupt, B.H. (1999). "First Discovery of Dinosaurs in the American West." Pp. 59-65 in Gillette, D.D. (ed.), Vertebrate Paleontology In Utah. Utah Geological Survey. ISBN 1-55791-634-9, ISBN 978-1-55791-634-1
  2. ^ Breithaupt, B.H. (2001). "Passport-In-Time Microvertebrate Fossil Project at the University of Wyoming Geological Museum: Late Cretaceous Paleontological Resources in the Public Eye." Pp. 107-112 in Santucci, V.L., and McClelland, L. (eds.), Proceedings of the 6th Fossil Resources Conference, United States Department of Interior - National Park Services - Geological Resources Division.
  3. ^ Cope, E.D. (1872). "On the existence of Dinosauria in the Transition Beds of Wyoming." Proceedings of the American Philosophical Society, 12: 481-483.
  4. ^ Cope, E.D. (1873). "The monster of Mammoth Buttes." Pennsylvania Monthly, 4: 521-534.
  5. ^ Cope, E.D. (1889). "The horned Dinosauria of the Laramie." The American Naturalist, 23: 715-717.
  6. ^ Burkhardt, R., 1892. "Das Gehirn von Agathaumas flabellatus Marsh". Neues Jahrbuch für Mineralogie, Geologie und Paläontologie 1892: 71-72
  7. ^ Ballou, W.H., 1897. "Strange creatures of the past, Gigantic saurians of the reptilian age", Century Magazine (New Series) XXXIII o.s. LV 15-23
  8. ^ a b AMNH, Department of Vertebrate Paleontology. (1904). "Review List of Casts, Models, and Photographs of fossil Vertebrates." Supplement to Bulletin of the American Museum of Natural History, vol. 20.
  9. ^ Sternberg, C. H. (1914). Notes on the Fossil Vertebrates Collected on the Cope Expedition to the Judith River and Cow Island Beds, Montana, in 1876. Science, 134-135.
  10. ^


  • Peter Dodson; The Horned Dinosaurs (1996)
  • Donald F. Glut; The Dinosaur Scrapbook