▁evol ved ▁during ▁the ▁C ret ace ous . ▁Rec ently ▁a ▁close ▁relationship ▁with ▁Per i pty ch idae ▁has ▁been ▁suggested . ▁This ▁would ▁make ▁p ant od ont s ▁crown - group ▁ung ulate ▁pla cent als ▁and ▁not ▁related ▁to ▁c im ol est ids ▁at ▁all . ▁ ▁Gener a ▁from ▁North ▁America ▁t ended ▁to ▁be ▁large ▁and ▁robust , ▁starting ▁with ▁P ant ol ambda ▁and ▁Ca en ol ambda ▁in ▁the ▁Middle ▁Pale oc ene ▁epo ch , ▁and ▁later ▁in ▁the ▁epo ch ▁started ▁to ▁get ▁larger , ▁with ▁B ary lambda ▁as ▁the ▁largest ▁Pale oc ene ▁form ▁of ▁p ant od ont . ▁However , ▁Asian ▁forms , ▁such ▁as ▁Arch ae ol ambda , ▁t ended ▁to ▁be ▁th inner ▁and ▁less ▁robust , ▁around ▁the ▁size ▁of ▁a ▁medium - s ized ▁dog . ▁Only ▁later ▁in ▁the ▁E oc ene , ▁with ▁Hyper c ory ph odon , ▁did ▁Asian ▁p ant od ont s ▁get ▁large ▁and ▁robust . ▁ ▁Tim eline ▁of ▁gener a ▁ ▁References ▁ ▁Foot notes ▁ ▁External ▁links ▁Pale oc ene - M amm als ▁▁▁ ▁Category : M amm al ▁sub orders ▁Category : P ri ab onian ▁ext in ctions ▁Category : P ale oc ene ▁first ▁appearances ▁Category : F oss il ▁tax a ▁described ▁in ▁ 1 8 7 3 ▁Category : T ax a ▁named ▁by ▁Edward ▁Dr ink er ▁C ope <0x0A> </s> ▁Y ah ya ▁K