Affixes

Most such names are of fossil genera, one exception being Ceratotherium (Greek keras, kerat‑, horn), the genus containing the white rhino. Examples of fossil species are Deinotherium (Greek deinos, terrible), an elephant-like mammal found mainly in the Pliocene epoch; Hyracotherium (Greek hurax, shrew-mouse), the earliest fossil ancestor of the horse from the Eocene epoch; and Megatherium (Greek megas, great), an extinct giant ground sloth of the Pliocene and Pleistocene epochs in America. Names for fossil genera are often written with lower-case initial letter as a general term for a member of the genus and can then be made plural, either in ‑theria (megatheria) or by adding ‑s.