The Collaborative International Dictionary of English v.0.48:

Paleotherium \Pa`le*o*the"ri*um\
   (p[=a]`l[-e]*[-o]*th[=e]"r[i^]*[u^]m), n. [NL., fr. Gr.
   palaio`s ancient + qhri`on beast.] (Paleon.)
   An extinct genus of herbivorous Tertiary mammals, once
   supposed to have resembled the tapir in form, but now known
   to have had a more slender form, with a long neck like that
   of a llama. [Written also Pal[ae]otherium.]
   [1913 Webster]