The Collaborative International Dictionary of English v.0.48:

Dinoceras \Di*noc"e*ras\, n. [NL., fr. Gr. ? terrible + ?, ?,
   horn.] (Paleon.)
   A genus of large extinct Eocene mammals from Wyoming; --
   called also Uintatherium. See Illustration in Appendix.
   [1913 Webster]

   Note: They were herbivorous, and remarkable for three pairs
         of hornlike protuberances on the skull. The males were
         armed with a pair of powerful canine tusks.
         [1913 Webster]

WordNet (r) 3.0 (2006):

dinoceras
    n 1: a variety of dinocerate [syn: dinoceras, uintathere]