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Temporal range: Late Cretaceous, 66 Ma
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Clade: Dinosauria
Order: Ornithischia
Family: Ceratopsidae
Genus: Polyonax
Cope, 1874
P. mortuarius
Binomial name
Polyonax mortuarius
Cope, 1874

Polyonax (meaning "master over many") was a genus of ceratopsid dinosaur from the late Maastrichtian-age Upper Cretaceous Denver Formation of Colorado, United States. Founded upon poor remains, it is today regarded as a dubious name.


During an 1873 trip through the western US, paleontologist and naturalist Edward Drinker Cope collected some fragmentary dinosaurian material which he soon named as a new genus.[1] Catalogued today as AMNH FR 3950,[2] the type material included three dorsal vertebrae, limb bone material, and what are now known to be horn cores, from a subadult individual.[3] Although it was briefly mixed up with hadrosaurs, and even considered to be a possible synonym of Trachodon,[4] it was recognized as a horned dinosaur in time for the first monograph on horned dinosaurs (1907), wherein it was regarded as based on indeterminate material.[5] Today, the name is used as little more than a historical curiosity, as it dates from a time before horned dinosaurs were known to exist.[6] The most recent review listed it as an indeterminate ceratopsid.[7]

It has sometimes been listed as a synonym of Agathaumas,[8] or Triceratops.[9]


As a ceratopsid, Polyonax would have been a large, quadrupedal herbivore, with brow and nasal horns and a neck frill.[7]

See also[edit]


  1. ^ Cope, E.D. (1874). Report on the stratigraphy and Pliocene vertebrate paleontology of northern Colorado. Bulletin of the U.S. Geological and Geographical Survey of the Territories. 9:9-28.
  2. ^ "American Museum of Natural History - Division of Paleontology - FR 3950".
  3. ^ Glut, D.F. (1997). "Polyonax". Dinosaurs: The Encyclopedia. McFarland & Company. pp. 723–724. ISBN 978-0-89950-917-4.
  4. ^ Hatcher, J.B. (1902). The genus and species of the Trachodontidae (Hadrosauridae, Claosauridae) Marsh. Annals of the Carnegie Museum 14(1):377-386.
  5. ^ Hatcher, J.B., Marsh, O.C., and Lull, R.S. (1907). The Ceratopsia. Government Printing Office:Washington, D.C., 300 pp. ISBN 0-405-12713-8
  6. ^ Dodson, P. (1996). The Horned Dinosaurs. Princeton University Press:Princeton, New Jersey. ISBN 978-0-691-02882-8.
  7. ^ a b Dodson, P., Forster, C.A., and Sampson, S.D. (2004). Ceratopsidae. In: Weishampel, D.B., Dodson, P., and Osmólska, H. (eds.). The Dinosauria (second edition). University of California Press:Berkeley, 494-513. ISBN 0-520-24209-2.
  8. ^ Romer, A.S. (1956). Osteology of the Reptiles. University of Chicago Press:Chicago, 1-772. ISBN 0-89464-985-X.
  9. ^ Lambert, D., and the Diagram Group. (1990). The Dinosaur Data Book. Facts on File:Oxford, England, 320 p.