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Temporal range: Miocene
Syndyoceras skeleton.jpg
Skeleton, Nebraska State Museum of Natural History
Scientific classification edit
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Protoceratidae
Genus: Syndyoceras
Species: S. cooki
Binomial name
Syndyoceras cooki
Barbour, 1905

Syndyoceras is a small extinct genus of Artiodactyla, of the family Protoceratidae, endemic to central North America from the Miocene epoch (24.8—20.6 Ma), existing for approximately 4.2 million years.[1]


Restoration by Robert Bruce Horsfall

Syndyoceras was named by Barbour (1905). Its type is Syndyoceras cooki. It was assigned to Protoceratidae by Barbour (1905) and Carroll (1988); and to Kyptoceratini by Webb (1981), Prothero (1998), Webb et al. (2003) and Prothero and Ludtke (2007).[2][3][4][5]


The skull decoration of Syndyoceras looked quite unlike those of a deer. It had two pairs of horns. The first was a V-shaped pair on the snout, fused at the base. The second pair was placed between the eyes and the ears and was curved inwards, the horns facing towards each other in a semicircular shape. Like giraffe ossicones, these protrusions were covered with skin. They were probably used for display and fighting.[6]

In addition to the horns, Syndyoceras also possessed tusk-like canine teeth, that it may have used to root through soil and undergrowth for food, in a similar manner to a modern musk deer. The shape of the skull also suggests that it may have had an inflated muzzle, like that of a modern saiga.[6]

The 5.2-foot-long (1.6 m), creature closely resembled a deer, having two hooved toes and reaching a weight over 60 kg.[7] Like early horses, such as Merychippus, it had two vestigial outer toes on each foot, which did not touch the ground.


  1. ^ PaleoBiology Database: Syndyoceras, basic info
  2. ^ E. H. Barbour. 1905. Nebraska Geological Survey 2(3)
  3. ^ R. L. Carroll. 1988. Vertebrate Paleontology and Evolution. W. H. Freeman and Company, New York 1-698
  4. ^ S. D. Webb. 1981. Journal of Vertebrate Paleontology 1(3-4)
  5. ^ D. R. Prothero and J. A. Ludtke. 2007. Family Protoceratidae. in D. R. Prothero and S. Foss (eds.), The Evolution of Artiodactyls 169-176
  6. ^ a b Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 273. ISBN 1-84028-152-9.
  7. ^