Agathaumas
From Ancient Greek 'αγαν' (agan, 'much') and 'θαυμα' (thauma, 'wonder'); meaning 'much wonder', given by Cope in reference to the large size of the type material.
Agathaumas is a dubious genus of a large ceratopsid dinosaur that lived in Wyoming during the Late Cretaceous (late Maastrichtian stage, 66 million years ago). It was seen as the largest land animal known at the time of its discovery.
Species
Agathaumas sylvestris Cope, 1872 Nomen dubium
Type species
From Latin 'sylvestris' (of the forest, wild). Cope (1872) coined the binomial as 'marvelous forest-dweller', in reference to the great size of the animal and to the forested environment indicated by plant fossils from the same beds.
- Holotype
- AMNH FR 4000 , American Museum of Natural History
- Material
- Sixteen vertebrae (including a sacrum, with dorsals and caudals), both ilia and other pelvic bones (those of one side nearly perfect), limb bones, ribs, and other undetermined parts.
- Horizon
- Lance Formation, Maastrichtian, Late Cretaceous , 72.2–66.0 million years ago
- Locality
- Black Buttes Station, near the Hallville Coal Mines, Wyoming, United States
References
- Cope, E. D. (1872). On the existence of Dinosauria in the transition beds of Wyoming. Proceedings of the American Philosophical Society (separate) 1-2. cope1872a
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Olshevsky, G. (1991). A revision of the parainfraclass Archosauria Cope, 1869, excluding the advanced Crocodylia. Mesozoic Meanderings 2: 1-196.
Lists Agathaumas as a nomen dubium and queries its synonymy with Brachyceratops.
olshevsky1991a -
Weishampel, D. B.; Dodson, P.; Osmólska, H. (eds.) (2004). The Dinosauria, Second Edition. University of California Press, Berkeley.
Lists Agathaumas sylvestris among the ceratopsid nomina dubia.
weishampel2004a -
Jones, B. (2026). The Princeton Encyclopedia of Dinosaurs: Ornithischians. Princeton University Press.
Treats Agathaumas as a nomen dubium on undiagnostic postcranial remains.
jones2026a