, ▁around ▁ 1 5 – 1 6 ▁my a . ▁This ▁makes ▁A pe om yo ides ▁the ▁young est ▁known ▁a pe omy ine , ▁and ▁its ▁occurrence ▁helps ▁close ▁a ▁gap ▁in ▁the ▁known ▁ge ographic ▁range ▁of ▁North ▁American ▁a pe omy ines ▁between ▁M ega pe om ys ▁b ob w il son i ▁elsewhere ▁in ▁Nev ada ▁and ▁A rik are e om ys ▁in ▁Neb r aska . ▁Other ▁e omy ids ▁found ▁at ▁East gate ▁include ▁species ▁of ▁Le pt od ont om ys ▁and ▁Pseud other id om ys . ▁ ▁References ▁ ▁Liter ature ▁c ited ▁ ▁Category : Ge omy oid ▁rod ents ▁Category : M i oc ene ▁rod ents ▁Category : Pre histor ic ▁m amm als ▁of ▁North ▁America ▁Category : Mon ot yp ic ▁m amm al ▁gener a ▁Category : Pre histor ic ▁rod ent ▁gener a <0x0A> </s> ▁The ▁Puerto ▁Rico ▁Sym phony ▁Orchestra ▁( PR SO ) ▁( Or questa ▁S inf ónica ▁de ▁Puerto ▁Rico ▁in ▁Spanish ) ▁a ▁musical ▁ensemble ▁spons ored ▁by ▁the ▁Government ▁of ▁Puerto ▁Rico . ▁It ▁has ▁ 8 0 ▁regular ▁mus icians ▁from ▁around ▁the ▁world ▁performing ▁a ▁ 5 2 - week ▁season ▁which ▁includes ▁sym ph onic ▁concert s , ▁oper as , ▁bal lets , ▁pop s , ▁and ▁other ▁activities . ▁ ▁History ▁The ▁history ▁of ▁the ▁PR SO ▁dates ▁back ▁to ▁ 1 9 5 8 ▁when ▁f amed ▁cell ist ▁Don ▁Pablo