• Webster's Revised Unabridged Dictionary
    • n Pliohippus (Paleon) An extinct genus of horses from the Pliocene deposits. Each foot had a single toe (or hoof), as in the common horse.
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Century Dictionary and Cyclopedia
    • n pliohippus A genus of fossil horses or Equidæ from the Pliocene of North America.
    • n pliohippus [lowercase] A horse of this genus.
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Webster's Revised Unabridged Dictionary
NL., fr. E. plio,cene + Gr. horse


In literature:

Pliohippus is a further intermediate form.
"The Story of Evolution" by Joseph McCabe
The first one-toed horse, Pliohippus, about forty inches high at the shoulder.
"The Outline of Science, Vol. 1 (of 4)" by J. Arthur Thomson
This animal lived in Europe while the Pliohippus and the Protohippus were flourishing in America.
"Earth and Sky Every Child Should Know" by Julia Ellen Rogers