ium ▁( ▁) ▁is ▁an ▁ext inct ▁genus ▁of ▁cam el id , ▁en demic ▁to ▁North ▁America . ▁They ▁lived ▁from ▁the ▁E oc ene ▁to ▁Mi oc ene ▁epo chs , ▁ 4 6 . 3 — 1 3 . 6 ▁my a , ▁existing ▁for ▁approximately ▁. ▁ ▁Disc overy ▁and ▁history ▁▁ ▁Po eb ro ther ium ▁was ▁first ▁named ▁by ▁scient ist ▁Joseph ▁Le id y ▁in ▁ 1 8 4 8 , ▁and ▁its ▁relationship ▁to ▁other ▁White ▁River ▁foss ils ▁was ▁later ▁expanded ▁by ▁him ▁in ▁ 1 8 5 3 . ▁Fur ▁tra pper ▁Samuel ▁C ul bert son ▁was ▁working ▁in ▁Neb r aska ▁in ▁purs uit ▁of ▁fur ▁bearing ▁m amm als , ▁and ▁found ▁a ▁collection ▁of ▁strange ▁foss il ▁animal ▁b ones . ▁He ▁sent ▁a ▁box ▁of ▁these ▁b ones ▁to ▁his ▁family ▁back ▁east , ▁and ▁not ▁knowing ▁what ▁to ▁make ▁of ▁them , ▁they ▁forward ed ▁the ▁remains ▁to ▁Le id y ▁for ▁identification . ▁Several ▁animals ' ▁remains ▁were ▁included ▁in ▁this ▁package , ▁but ▁one ▁of ▁the ▁most ▁interesting ▁was ▁that ▁of ▁a ▁small ▁m amm al , ▁about ▁the ▁size ▁of ▁a ▁small ▁de er ▁or ▁sheep . ▁In ▁addition ▁to ▁a ▁partial ▁sk ull , ▁a ▁portion ▁of ▁a ▁for el imb ▁was ▁found . ▁The ▁port ions ▁that ▁Le id y ▁was ▁able ▁to ▁examine ▁helped ▁him ▁determine ▁it ▁was ▁likely ▁related ▁to ▁modern ▁llam as , ▁even ▁though ▁there ▁was ▁a ▁pau