Outline Restoration by Charles R. Knight [7]
__________________________

[1] Scott, William, A History of Land Mammals in the Western Hemisphere, (New York: The MacMillian Co., 1913), 272
[2] Bennet, Deb, The Evolution of the Horse: History and Techniques of Study, 2008, 14
[3] https://en.wikipedia.org/wiki/Orohippus
[4] Woodward, Henry, A Guide to the Fossil Mammals and Birds in the Department of Geology and Palaeontology in the British Museum (Natural History), (London: Harrison and Sons, 1896), 38
[5] Ibid
[6] National Museum of Natural History, Smithsonian Institution, Washington, DC, USA.
[7] Osborn, Henry, The Age of Mammals in Europe, Asia and North America, (New York: The MacMillian Co., 1921), 162
[8] Granger, Walter, Article XV - A Revision of the American Eocene Horses, (American Museum of Natural History,1908), Vol. XXIV, Plate XVII
[9] Marsh, O.C., Fossil Horses in America,The American Naturalist, Vol. 8, No. 5, (The University of Chicago Press for The American Society of Naturalists, May 1874), 289. Retrieved from http://www.jstor.org/stable/2447952 (Gray added)


Skull and Jaw [8]
Orohippus osbornianus
A - Skull half, inferior view
B - Lower jaw half, occusal view
Fd. Bridger Formation, Wyoming, USA
12648 American Museum Collection
A
B
By Daderot [Public domain], from Wikimedia Commons
Skeleton [6]
Orohippus pumilus
Restoration by Charles R. Knight (1896)
via Wikimedia Commons
Foreleg [9]
Orohippus agilis
Orohippus
Copyright 2018 All rights reserved.

 

Size

Small, no bigger than a fox [1]

Eye sockets

Incomplete bony rim, about 0.5 of skull length from front of skull to center of socket

Type of teeth

Low crowned, enamel over dentine [2]

Toes

Four toes on each foreleg, three toes on each hindleg [3], all toes will touch ground

Hooves/pads

Pad on each toe

Locations found

North America [4]

Other

“Prof. Cope states that the American Orohippus is identical to Hyracotherium” [5]

Back arched upward

There appears to be fifteen sets of ribs in the photo below

Anchippus
Anchitherium
Equus 1 (Recent)
Equus 2 (Recent)
Equus 1 (Fossils)
Equus 2 (Fossils)
Hipparion
Hippidion
Hypohippus
Kalobatippus
Merychippus
Mesohippus
Miohippus
Nannippus
Neohipparion
Orohippus
Parahippus
Pliohippus
Protohippus
Protorohippus
Unidentified
Hyracotherum (Eohippus)
Horse Evolution?