ys ▁med emi ) ▁is ▁a ▁species ▁of ▁t urt le ▁in ▁the ▁family ▁E my d idae ▁en demic ▁to ▁north western ▁Colombia . ▁It ▁was ▁described ▁in ▁ 2 0 1 7 . ▁ ▁Geographic ▁range ▁The ▁A tr ato ▁slider ' s ▁ge ographical ▁range ▁is ▁in ▁the ▁lower ▁A tr ato ▁river ▁bas in ▁of ▁Ant io quia ▁and ▁Ch oc ó ▁depart ments ▁of ▁north western ▁Colombia , ▁near ▁the ▁Pan aman ian ▁border . ▁ ▁E volution ary ▁history ▁There ▁were ▁two ▁major ▁migr ations ▁of ▁sl iders ▁into ▁South ▁America ▁during ▁the ▁Great ▁American ▁Inter change ▁of ▁the ▁C en oz o ic . ▁During ▁the ▁first ▁migration , ▁which ▁occurred ▁about ▁ 7 . 1 - 8 . 6 ▁million ▁years ▁ago , ▁the ▁last ▁recent ▁common ▁ancest or ▁of ▁T . ▁med emi ▁and ▁T . ▁d orb ign i ▁spread ▁from ▁Central ▁America ▁into ▁South ▁America , ▁with ▁T . ▁d orb ign i ▁expand ing ▁into ▁the ▁eastern ▁parts ▁of ▁the ▁continent ▁while ▁T . ▁med emi ▁remained ▁in ▁present - day ▁Colombia . ▁T . ▁med emi ▁diver ged ▁from ▁T . ▁d orb ign i ▁about ▁ 2 . 8 - 4 . 1 ▁million ▁years ▁ago , ▁with ▁T . ▁d orb ign i ▁divers ifying ▁about ▁ 1 . 9 - 2 . 3 ▁million ▁years ▁ago . ▁In ▁the ▁meant ime , ▁during ▁the ▁second ▁migration ▁of ▁Tra chem ys ▁sl iders ▁ 2 . 2 -