An yi imanin cewa tsoffin marsupials sun yi hijira daga abin da yanzu ke Kudancin Amurka zuwa Ostiraliya dubun miliyoyin shekaru da suka gabata a lokacin Gondwana, kuma sun samo asali yayin da Ostiraliya ta zama mafi ƙaranci. An samo burbushin halittu na jinsunan da suka yi kama da aljannu na zamani, amma ba a san ko sun kasance kakannin jinsunan zamani ba, ko kuma ko aljannu na yanzu sun kasance tare da waɗannan nau'ikan. Ba a san ranar da aljan Tasmanian ya zama a cikin gida ba daga yankin Australiya ba; mafi yawan shaidu sun nuna cewa sun yi kwangila zuwa ga al'ummomi uku da suka rage a kusa da shekaru 3000 da suka gabata. An gano hakori a Augusta, Western Australia a cikin shekaru 430 da suka gabata, amma masanin ilimin kimiyyar ilmin kimiyyar Oliver Brown ya yi jayayya da wannan kuma ya yi la'akari da asarar babban yankin shaidan ya faru a kusa da shekaru 3000 da suka gabata.
aljannu