Mu 2011, akatswiri ofufuza zinthu zakale anapeza mwala wosungidwa bwino wa anamgumi amiyendo inayi otchedwa Peregocetus pacificus - kupezedwa komwe kumapereka chidziwitso chatsopano pakusintha kwa nyama zoyamwitsa kuchokera kumtunda kupita kunyanja.
Makolo a anamgumi ndi ma dolphin adayenda Padziko Lapansi zaka 50 miliyoni zapitazo m'magawo omwe tsopano aku India subcontinent.
Paleontologists m'mbuyomu adapeza zotsalira zamitundu ya ku North America zomwe zinali zaka 41.2 miliyoni zomwe zikuwonetsa kuti panthawiyi, ma cetaceans anali atalephera kunyamula zolemera zawo ndikuyenda padziko lapansi.
Chitsanzo chatsopanochi, chofotokozedwa mu kafukufuku yemwe adasindikizidwa mu Epulo 2019 Current Biology, anali ndi zaka 42.6 miliyoni ndipo adapereka chidziwitso chatsopano pakusintha kwa cetaceans.
Zotsalira zakalezi zinapezedwa pafupifupi makilomita 0.6 (kilomita imodzi) kumtunda kuchokera kugombe la Pacific la Peru, ku Playa Media Luna.
Mandibles ake adadyetsera nthaka ya m'chipululu ndipo pofukula, ofufuzawo adapeza nsagwada zapansi, mano, vertebrae, nthiti, mbali za kutsogolo ndi kumbuyo kwa miyendo, komanso zala zazitali za kholo la whale zomwe mwina zinali zokopa.
Kutengera ndi momwe thupi lake limakhalira, asayansi adazindikira kuti cetacean iyi yautali pafupifupi 13 (mamita anayi) imatha kuyenda ndi kusambira.
Malinga ndi kunena kwa wolemba wamkulu Olivier Lambert wa ku Royal Belgian Institute of Natural Sciences, “mbali ina ya fupa la fupa la msana wa mchirawo inasonyeza kufanana ndi nyama zamasiku ano zokhala m’mphepete mwa madzi monga otters.”
"Chotero ichi chikanakhala chinyama chomwe chikanayamba kugwiritsa ntchito kwambiri mchira wake kusambira, zomwe zimasiyanitsa ndi cetaceans zakale ku India ndi Pakistan," adatero Lambert.
Zidutswa za anamgumi amiyendo inayi zinapezedwa m’mbuyomo ku Egypt, Nigeria, Togo, Senegal ndi Western Sahara, koma zinali zogaŵikana kwambiri kotero kuti zinali zosatheka kuganiza motsimikiza ngati angathe kusambira.
Lambert anati: “Ichi ndiye chitsanzo chathunthu cha namgumi wamiyendo inayi kunja kwa India ndi Pakistan.
Ngati namgumi wa ku Peru akanatha kusambira ngati otter, ofufuzawo anaganiza kuti mwina anawoloka nyanja ya Atlantic kuchokera kugombe lakumadzulo kwa Africa kupita ku South America. Chifukwa cha kugwedezeka kwa kontinenti, mtunda unali theka la masiku ano, pafupifupi makilomita 800, ndipo mphamvu ya kummawa ndi kumadzulo kwa nthawiyo ikanawathandiza kuyenda.
Kupeza kumeneku kungapangitse kuti kusakhalenso lingaliro lina lolingana ndi momwe anamgumi adafikira kumpoto kwa America kudzera ku Greenland.
Mphepete mwa nyanja ya Pisco, yomwe ili kumphepete mwa nyanja ya kumwera kwa Peru, mwachiwonekere ili ndi zokwiriridwa zakale zambiri, chifukwa chakuti ndi yabwino kwambiri kuti isungidwe. Akatswiri ofufuza zinthu zakale amanena kuti “ali ndi ntchito kwa zaka 50 zikubwerazi.”
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