▁b ark eri . ▁Prim itive ▁versions ▁of ▁hem og lo bin ▁have ▁been ▁found ▁in ▁M . ▁ac et iv or ans , ▁suggesting ▁the ▁micro be ▁or ▁an ▁ancest or ▁of ▁it ▁may ▁have ▁played ▁a ▁cru cial ▁role ▁in ▁the ▁evolution ▁of ▁life ▁on ▁Earth . ▁ ▁Species ▁of ▁M eth anos arc ina ▁are ▁also ▁noted ▁for ▁unus ually ▁large ▁genom es . ▁M . ▁ac et iv or ans ▁has ▁the ▁largest ▁known ▁gen ome ▁of ▁any ▁arch ae on . ▁ ▁According ▁to ▁a ▁theory ▁published ▁in ▁ 2 0 1 4 , ▁M eth anos arc ina ▁may ▁have ▁been ▁largely ▁responsible ▁for ▁the ▁largest ▁ext inction ▁event ▁in ▁the ▁Earth ' s ▁history , ▁the ▁Perm ian – Tri ass ic ▁ext inction ▁event . ▁ ▁The ▁theory ▁suggests ▁that ▁ac quisition ▁of ▁a ▁new ▁met abol ic ▁path way ▁via ▁gene ▁transfer ▁followed ▁by ▁exponential ▁reprodu ction ▁allowed ▁the ▁micro be ▁ ▁to ▁rapidly ▁consume ▁vast ▁depos its ▁of ▁organ ic ▁carbon ▁in ▁ ▁marine ▁sed iments , ▁leading ▁to ▁a ▁sharp ▁bu il dup ▁of ▁m eth ane ▁and ▁carbon ▁dio x ide ▁in ▁the ▁Earth ' s ▁o ce ans ▁and ▁atmosphere ▁that ▁killed ▁around ▁ 9 0 % ▁of ▁the ▁world ' s ▁species . ▁ ▁This ▁theory ▁could ▁better ▁explain ▁the ▁observed ▁carbon ▁is ot ope ▁level ▁in ▁period ▁depos its ▁than ▁other ▁theories ▁such ▁as ▁vol can ic ▁activity . ▁ ▁M eth anos arc ina ▁has ▁been ▁used