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Title: Moropus  
Author: World Heritage Encyclopedia
Language: English
Subject: Chalicothere, Chalicotheres, Journey to the Beginning of Time, White River Fauna, Chalicotherium
Publisher: World Heritage Encyclopedia


Temporal range: Early Miocene, 23–13.6 Ma
Moropus elatus skeleton at the
National Museum of Natural History,
Washington, DC
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Suborder: Ancylopoda
Superfamily: Chalicotherioidea
Family: Chalicotheriidae
Subfamily: Schizotheriinae
Genus: Moropus
Marsh, 1877
  • M. distans Marsh 1877
  • M. elatus Marsh 1877
  • M. hollandi Peterson 1907
  • M. matthewi Holland and Peterson 1913
  • M. merriami Peterson 1914
  • M. oregonensis Leidy 1873
  • M. senex Marsh 1877

Moropus (meaning "slow foot") is an extinct genus of perissodactyl ("odd-toed") mammal that belonged to the group called chalicotheres, which were endemic to North America during the Miocene from ~23.0—13.6 Mya, existing for approximately .

Moropus is related to the modern horse, rhino, and tapir.[1]


  • Taxonomy 1
  • Morphology 2
  • Fossil distribution 3
  • Species 4
    • M. elatus 4.1
    • M. hollandi 4.2
    • M. matthewi 4.3
    • M. merriami 4.4
    • M. oregonensis 4.5
    • M. senex 4.6
  • See also 5
  • References 6


Moropus was named by Marsh (1877). Its type is Moropus distans. It was synonymized subjectively with Macrotherium by Osborn (1893). It was assigned to Moropodidae by Marsh (1877); to Chalicotheriidae by Marsh (1877), Peterson (1907), Skinner (1968), Coombs (1978), Carroll (1988), Coombs (1998) and Holbrook (1999); and to Schizotheriinae by Geraads et al. (2007).[2][3]


Restoration of Moropus threatening a pair of Daphoenodon, from a paleoart mural by Jay Matternes

Like other chalicotheres, they differed from their modern relatives in having large claws, rather than hooves, on the front feet; these claws may have been used for defense or digging for food.[1] Moropus stood about 8 feet (2.4 m) tall at the shoulder. The three highly compressed claw-like hooves on each foot were split down the middle. These claws actually gave Moropus its name: "slow (or sloth) foot". This name implies that because of the claws, Moropus was a clumsy mover. But the articulation of the phalangeal (finger) bones, in addition to the likely presence of large foot and toe pads, shows that Moropus probably could raise the claws slightly to enable it to move about quite smoothly. As the hooves curved inward, it probably had a pigeon-toed gait.

Fossil distribution

First complete skeletal restoration, 1918


M. elatus

M. elatus specimen, AMNH
Restoration of M. elatus by Robert Bruce Horsfall

M. elatus was named by Marsh (1877).

Body mass

Two specimens were examined by M. Mendoza, C. M. Janis, and P. Palmqvist for body mass.[4]

  • Specimen 1: 118.4 kg (260 lb)
  • Specimen 2: 296.8 kg (650 lb)

Fossil distribution

M. hollandi

M. hollandi was named by Peterson (1907).[5]

Fossil distribution

M. matthewi

M. matthewi was named by Holland and Peterson, 1913-1914.

M. merriami

M. merrami was named by Holland and Peterson (1914). It was recombined as Macrotherium merriami by Matthew (1929) and Stirton (1939); it was recombined as Chalicotherium merriami by von Koenigswald (1932).

Fossil distribution

  • High Rock Canyon, Humboldt County, Nevada, estimated age: ~17.2 Mya.
  • Virgin Valley, Humboldt County, Nevada, estimated age: ~16.3 Mya.
  • Humbug Quarry, Sioux County, Nebraska, ~16.5—16.25 Mya.
  • Echo Quarry, Sioux County, Nebraska, ~16.3—13.6 Mya.

M. oregonensis

M. oregonsis was named by Leidy 1873. It was named by Leidy (1873) and recombined as Moropus oregonensis by Holland and Peterson (1914) and M. C. Coombs in 1978 and 1998, and also by M. C. Coombs, R. M. Hunt, E. Stepleton, L. B. Albright, III, and T. J. Fremd.[6]

Body mass

Two specimens were examined by M. Mendoza, C. M. Janis, and P. Palmqvist for body mass.[7]

  • Specimen 1: 58.4 kg (130 lb)
  • Specimen 2: 90.3 kg (200 lb)

Fossil distribution

M. senex

M. senex was named by Marsh (1877). It was considered a nomen dubium by Coombs (1978) and Coombs (1998).

See also


  1. ^ a b Palmer, D., ed. (1999). The Marshall Illustrated Encyclopedia of Dinosaurs and Prehistoric Animals. London: Marshall Editions. p. 261.  
  2. ^ O. C. Marsh. 1877. Notice of some new vertebrate fossils. American Journal of Arts and Sciences 14:249-256
  3. ^ D. Geraads, E. Tsoukala, and N. Spassov. 2007. A skull of Ancylotherium (Chalicotheriidae, Mammalia) from the late Miocene of Thermopigi (Serres, N. Greece) and the relationships of the genus. Journal of Vertebrate Paleontology 27(2):461-466
  4. ^ M. Mendoza, et al.
  5. ^ O. A. Peterson. 1907. Annals of Carnegie Museum 4(3)
  6. ^ M. C. Coombs, R. M. Hunt, E. Stepleton, L. B. Albright, III, and T. J. Fremd in 2001. Stratigraphy, chronology, biogeography, and taxonomy of early Miocene small chalicotheres of North America. Journal of Vertebrate Paleontology 21(3):607-620
  7. ^ M. Mendoza, et al. p. 270(1):90-101
  • Cambridge Journals Online, Journal of Zoology
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