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Agathaumas

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Agathaumas
Temporal range: Late Cretaceous, 66 Ma
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Illustration of the vertebrae and sacrum
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Clade: †Ornithischia
Clade: †Neornithischia
Clade: †Ceratopsia
Family: †Ceratopsidae
Subfamily: †Chasmosaurinae
Tribe: †Triceratopsini
Genus: †Agathaumas
Cope, 1872
Type species
†Agathaumas sylvestris
Cope, 1872
Species

See text

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 Greek, αγαν - 'much' and θαυμα - '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 ceratopsian known to science from more than teeth, 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]

History

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 (then Laramie 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. Cope later (in 1873) described the skeleton as "the wreck of one of the princes among giants."[3] Cope and his team eventually recovered complete hip bones, sacral vertebrae, and several ribs from the animal. 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.[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 such as Cetiosaurus and Pelorosaurus were land animals.[1]

Classification history

Cope originally did not know to what group Agathaumas belonged, though he noted that some of the remains were similar to the British reptile Cetiosaurus[4] and very different from the corresponding elements of Hadrosaurus and Dryptosaurus (Laelaps).[4] In 1882, Othniel Charles Marsh, Cope's rival in the Bone Wars, suggested that Agathaumas, along with Cionodon, another Cope taxon, was a Hadrosaurid.[5] In 1883, with his description of the skull of Edmontosaurus (Diclonius), Cope also suggested that his taxa Agathaumas, Monoclonius, and Dysganus could be Hadrosaurids.[6] Cope did not assign Agathaumas into the group now recognized as Ceratopsia until later in 1889, when Cope recognized that his genera Monoclonius and Polyonax were related due to Marsh's description of Triceratops fossils.[7] Marsh had already named a group for the horned dinosaurs, Ceratopsidae, but Cope did not recognize this family name as he believed Ceratops could not be distinguished from other taxa; Cope erected a new name, Agathaumidae.[7] Cope later named 2 more "Agathaumids", Manospondylus gigas and Claorhynchus trihedrus, based on fragmentary fossils in 1892, expanding his group to 5 genera.[8]

After reassessment by John Bell Hatcher, Richard Swann Lull, and Nelda Wright in the 1900s and 1930s, all of the members of Agathaumidae were found to be dubious,[9][10]and the family name Ceratopsidae was preferred over Agathaumidae.[9] Agathaumas itself was found to be a dubious Ceratopsid by Hatcher and Lull,[9] as well as by John Ostrom and Peter Wellnhofer who placed it as Triceratops sp.[11]

Species

Type:

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

Species previously referred to Agathaumas:

  • A. flabellatus (Marsh, 1889) Burkhardt, 1892; alternative combination for Triceratops flabellatus;[12] synonymous with Triceratops horridus.[13]
  • A. milo Cope, 1874; included with Thespesius occidentalis by Cope, dubious at Hadrosauridae family level.[14]
  • A. monoclonius (Breithaupt, 1994); nomen dubium included with Monoclonius sphenocerus
  • A. mortuarius (Cope, 1874) Hay, 1901; nomen dubium, alternative combination for Polyonax mortuarius; possible synonym of Triceratops horridus[14]
  • A. prorsus (Marsh, 1890) Lydekker, 1893; alternative combination of Triceratops prorsus, unused since
  • A. sphenocerus (Cope, 1890) Ballou, 1897; nomen dubium included with Monoclonius sphenocerus[15]

Unfortunately, due to the fragmentary nature of Agathaumas sylvestris’ holotype specimen, Agathaumas is a dubious taxon and cannot be referred beyond Ceratopsidae.[9] based on stratigraphy it is likely a member of Triceratopsini.[1]

Knight's restoration

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 preserved a large nasal horn, and Monoclonius recurvicornis, which preserved small horns over the eyes.[16] A. sphenoceros was originally referred to the genus Monoclonius and later to Styracosaurus,[17] while M. recurvicornis is a possibly a valid species but has yet to receive a new genus.[18] The body was based on a more complete skeleton of the species Triceratops prorsus that had been described by O.C. Marsh. The body armor depicted in the illustration was likely based on the squamosals of Pachycephalosaurus for the larger spikes, and the smaller armor on the dermal scutes of Denversaurus collected in Lance, Wyoming by Marsh's crews in the 1890s.[19] 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.[16] This painting was later used as basis for a model Agathaumas in the 1925 film The Lost World.[20]

See also

References

Wikimedia Commons has media related to Agathaumas.
  1. ^ a b c d Breithaupt, B.H. (1999). "First Discovery of Dinosaurs in the American West". In Gillette, D.D. (ed.). Vertebrate Paleontology In Utah. Utah Geological Survey. pp. 59–65. 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. (1873). "The monster of Mammoth Buttes". Pennsylvania Monthly. 4: 521–534.
  4. ^ a b c Cope, E.D. (1872). "On the existence of Dinosauria in the Transition Beds of Wyoming". Proceedings of the American Philosophical Society. 12: 481–483.
  5. ^ Marsh, O. C. (1882). "Classification of the Dinosauria". American Journal of Science. 3 (133): 81–86.
  6. ^ Cope, E. D. (1883). "On the characters of the skull in the Hadrosauridae". Proceedings of the Academy of Natural Sciences of Philadelphia. 35: 97–107. JSTOR 4060861.
  7. ^ a b Cope, E. D. (1889). The horned Dinosauria of the Laramie.
  8. ^ Cope, E. D. (1892). Fourth note on the Dinosauria of the Laramie.
  9. ^ a b c d Hatcher, J. B. (1907). The ceratopsia (No. 310). US Government Printing Office.
  10. ^ Lull, R. S., & Wright, N. E. (1942). Hadrosaurian dinosaurs of North America (Vol. 40). Geological Society of America.
  11. ^ Ostrom, J. H.; Wellnhofer, P. (1985). "The Munich specimen of Triceratops with a revision of the genus". Zitteliana. 14: 111–158.
  12. ^ Burkhardt, R., 1892. "Das Gehirn von Agathaumas flabellatus Marsh". Neues Jahrbuch für Mineralogie, Geologie und Paläontologie 1892: 71-72
  13. ^ Forster, C. A. (1996). Species resolution in Triceratops: cladistic and morphometric approaches. Journal of Vertebrate Paleontology, 16(2), 259-270.
  14. ^ a b Carpenter, K., & Young, D. B. (2002). Late Cretaceous dinosaurs from the Denver Basin, Colorado. Rocky Mountain Geology, 37(2), 237-254.
  15. ^ 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
  16. ^ 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.
  17. ^ 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.
  18. ^ Brown, B. (1914). A complete skull of Monoclonius, from the Belly River Cretaceous of Alberta. Bulletin of the AMNH; v. 33, article 34.
  19. ^ Greenfield, Tyler (2020-12-08). "Armor for Agathaumas". Incertae Sedis. Retrieved 2022-03-20.
  20. ^ "The Lost World: Marcel Delgado".
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