a dubious centrosaurine ceratopside dinosaur from the Late Cretaceous of North America.
(Great wonder) and Polyonax
(Master over many), Monoclonius
was E.D. Cope's third crack at naming a ceratopsian and the only one worth the paper it's written on. Everyone else thinks it's highly dubious, and that its "probably" juvenile remains belong to an already-named adult, (popular choice Centrosaurus
). The problem being; non-adult specimens of ceratopsian (horn faced dinosaurs) are notoriously difficult to identify at species level, even ones known from decent remains, which Monoclonius
Its holotype partial skull, complete with name-prompting teeth that most probably belong to a hadrosaur (duck-billed dinosaur) and have been carelessly misplaced, were discovered in 1876 at "the mouth of Dog Creek" in the Judith River Formation of Montana, and were excavated before tension in the area led to Custer's last stand against the Lakota-Northern Cheyenne Indians at battle of the little big horn later that year.
The fact that Cope had no idea that horned dinosaurs existed until his nemesis redescribed a "Pliocene-aged bison" as Triceratops
in 1889 led to lots of initial head-scratching. But since then, all and sundry busied themselves assigning copious amounts of farcically fragmentary fossils to Monoclonius
with gay abandon and raising over a dozen species along the way. Today though, only the original name-bearing specimen remains, but only by the skin of its long-lost teeth.
: Late Cretaceous
: 84-71 mya
Est. max. length
: 5.5 meters
Est. max. hip height
Est. max. weight
: 2 tons
("recurved horn", named by Cope in 1889 for AMNH 3999 from the Judith River Beds of Montana) is a nomen dubium.
("wedge-horned", named by Cope in 1889 for AMNH 3989, found by Sternberg in 1876 on Cow Island) is a nomen dubium.
("the split one", named by Cope in 1889 for AMNH 3988 from the Judith River Beds of Montana) is a nomen dubium.
("for Dawson", named by Lambe in 1902) is a subjective synonym of Centrosaurus apertus
("for John Bell Hatcher") was discovered by Lawrence Lambe in 1898 and named in 1902 on the assumption it was related to Cope's Monoclonius
, basically because all ceratopsians discovered in the Judith River Formation were assumed to be related to Cope's Monoclonius
However, Sternberg discovered more 'Monoclonius' remains in Alberta, Canada, and Lambe renamed them, along with his original fossils, Chasmosaurus belli
in 1914. But only because Protorosaurus
), his first choice, was already occupied by the earliest known archosauromorph.
("from Canada", named by Lambe in 1902) is now Chasmosaurus canadensis
(Lambe, 1904) is now classified as Centrosaurus apertus
("from Alberta", named by Lambe in 1913) is now classified as Styracosaurus albertensis
(Brown, 1914) is a subjective synonym of Centrosaurus apertus
("from Montana", named by Gilmore in 1914) is now known as Brachyceratops montanensis
("for Cutler", named by Brown in 1917) is a subjective synonym of Centrosaurus apertus
(Brown, 1917) is a subjective synonym of Styracosaurus albertensis
(Sternberg, 1940) is a junior synonym of Centrosaurus apertus
(Sternberg, 1940) is a synonym of Monoclonius crassus
(Dodson, 1986) is now Avaceratops lammersi
• Cope, E.D. (1876) "Descriptions of some vertebrate remains from the Fort Union Beds of Montana". Proceedings of the Academy of Natural Sciences of Philadelphia 28: 248-261.
• Brown, B. (1914) "A complete skull of the horned dinosaur Monoclonius,
from the Belly River of Alberta
". Bulletin of the American Museum of Natural History, 33: 549–558.
• Brown, B. (1917) "A complete skeleton of the horned dinosaur Monoclonius, and description of a second skeleton showing skin impressions
• Dodson, P. (1998) "Monoclonius - The First Ceratopsid" in "The Horned Dinosaurs: A Natural History
• Creisler, B.S. (September 1992) "Why Monoclonius
Cope Was Not Named for Its Horn: The Etymologies of Cope's Dinosaurs". JVP, Vol. 12.
• Dodson, P. (1990) "On the status of the ceratopsids Monoclonius
" in Dinosaur Systematics: Perspectives and Approaches
• Ryan, M.J. (2006) "The status of the problematic taxon Monoclonius
(Ornithischia: Ceratopsidae) and the recognition of adult-sized dinosaur taxa". Geological Society of America Abstracts with Programs, 38(4):62.
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