▁lower ▁their ▁eyes , ▁but ▁an ▁alternative ▁hypothesis ▁exists ▁in ▁which ▁sal am and ers ▁and ▁ca ec ili ans ▁are ▁each ▁other ' s ▁closest ▁relatives ▁as ▁part ▁of ▁a ▁cla de ▁called ▁the ▁Pro cera , ▁with ▁fro gs ▁position ed ▁as ▁the ▁sister ▁tax on ▁of ▁this ▁group . ▁ ▁Orig ins ▁The ▁earliest ▁b atra chi ans ▁are ▁the ▁stem - f ro gs ▁Tri ad ob at rach us ▁and ▁Cz at k ob at rach us ▁from ▁the ▁Early ▁Tri ass ic , ▁about ▁ 2 5 0 ▁million ▁years ▁ago . ▁However , ▁several ▁mole cular ▁clock ▁estimates ▁place ▁the ▁first ▁appearance ▁of ▁the ▁Bat rach ia ▁( the ▁time ▁at ▁which ▁f rog ▁and ▁sal am ander ▁line ages ▁diver ged ▁from ▁each ▁other ) ▁before ▁the ▁Early ▁Tri ass ic . ▁Most ▁estimates ▁place ▁the ▁diver gence ▁in ▁the ▁Perm ian ▁but ▁some ▁put ▁it ▁as ▁far ▁back ▁as ▁ 3 6 7 ▁million ▁years ▁ago ▁in ▁the ▁Late ▁Dev onian . ▁However , ▁there ▁is ▁no ▁evidence ▁of ▁l iss am ph ib ians ▁or ▁l iss am ph ib ian - like ▁animals ▁in ▁the ▁foss il ▁record ▁at ▁this ▁time . ▁The ▁t et rap od ▁groups ▁that ▁are ▁hypoth es ized ▁as ▁ancest ors ▁of ▁modern ▁am ph ib ians ▁( le pos pond yl s ▁and ▁am ph ib am id ▁tem nos pond yl s ) ▁appear ▁in ▁the ▁Late ▁Car bon ifer ous , ▁roughly ▁ 3