Asayansi ochokera ku Canada apeza ku Arctic zotsalira za cholengedwa chamapiko chomwe chidakhala padziko lapansi zaka 90 miliyoni zapitazo. Chifukwa cha izi, akatswiri ofufuza zinthu zakale adziwa momwe nyengo ya Arctic imakhalira nthawi zakale.
Mbalame yomwe anthu aku Canada adapeza inali Tingmaitornis arctica. Malinga ndi akatswiri ofufuza zakale, anali ndi mano ndipo amasaka nsomba zazikuluzikulu. Ananenanso kuti mbalameyi ndi kholo la mbalame zam'madzi zamakono ndipo mwina ngakhale kumira m'madzi kufunafuna chakudya pansi pamadzi.
Chosangalatsa ndichakuti, izi zidabweretsa ziganizo zodabwitsa. Poyerekeza zotsalira, zaka 90 miliyoni zapitazo, nyengo ya Arctic sinkagwirizana ndi zamakono ndipo inali yofanana ndi nyengo ya Florida masiku ano.
Zotsalazo zidaloleza asayansi kuti apange malingaliro ena pazakusintha kwanyengo komwe kudachitika kudera la Arctic ku Upper Cretaceous. Mwachitsanzo, asayansi am'mbuyomu, ngakhale adadziwa kuti nyengo ya Arctic ya nthawiyo inali yotentha kuposa momwe amakono, adaganiza kuti Arctic idakutidwabe ndi ayezi nthawi yozizira.
Zomwe apezazi zikusonyeza kuti kunali kotentha kwambiri kumeneko, popeza nyama zomwe mbalame zoterezi zimatha kudya zimangokhala nyengo yotentha. Chifukwa chake, mpweya waku Arctic wanthawiyo umatha kutentha mpaka 28 digiri Celsius.
Kuphatikiza apo, akatswiri ofufuza zakale apeza chigaza cha nyama yosadziwikabe yomwe idakhala ku California. Yemwe ali ndi chigaza sichidziwikebe, koma pali malingaliro akuti anali mammoth omwe adakhala zaka 30 zikwi zapitazo. Kuphatikiza apo, kufa kwa nyama kumalumikizidwa ndikuzizira kwapadziko lonse. Ngati lingaliroli likutsimikizika ndipo likhala lalikulu kwambiri, ndiye kuti likhala lakale kwambiri pamakontena onse aku North America.
