Mary Allen
Palaeozoic lokaci ne a cikin tarihin duniya. Ya fara kimanin shekaru miliyan 540 da suka wuce kuma ya ƙare kimanin shekaru miliyan 250 kafin zamaninmu. Don haka sashe ne na kusan shekaru miliyan 300.
An raba Palaeozoic zuwa lokuta daban-daban:
- Cambrian 540 zuwa 485 shekaru miliyan da suka wuce,
- Ordovician 485 zuwa 443 shekaru miliyan da suka wuce,
- Silurian 443 zuwa 420 shekaru miliyan da suka wuce,
- Devonian shekaru miliyan 420 zuwa 359 da suka wuce,
- Carboniferous 359 zuwa miliyan 300 da suka wuce kuma
- Permian 300 zuwa 250 shekaru miliyan da suka wuce.
Masana kimiyya kuma suna kiransa da Palaeozoic Era. Kalmar ta fito daga tsohuwar Hellenanci kuma ana iya fassara ta a matsayin “halittu na dā”. Zamanin Mesozoic, wanda dinosaur suka rayu, ya bi Palaeozoic. Lokacin mu na yanzu ana kiransa ilimin geologically Cenozoic Era.
Ta yaya nahiyoyi suka canza?
Duniya ta yi kama sosai da ta yau. A farkon Palaeozoic, ƙasa ta rufe ƙasa a kudu da babbar ƙasa: Gondwana. Yawancin wannan nahiya ta cika da ƙanƙara. Tudun sa na arewa, duk da haka, ya kai har zuwa ga equator. Akwai kuma ƙananan nahiyoyi uku a cikin wurare masu zafi, kudu da equator. Inda Turai take a yau, a lokacin akwai teku. A tsawon miliyoyin shekaru, nahiyoyi sun kara matsawa arewa.
Kimanin shekaru miliyan 400 da suka wuce, tsarin nahiyoyi ya canza sosai. Biyu daga cikin ƙananan nahiyoyi sun yi karo. An kafa nahiyar Laurussia. Lokacin da waɗannan talakawan ƙasa guda biyu suka hadu, tsaunuka sun yi girma, wasu daga cikinsu har yanzu suna wanzu. Waɗannan sun haɗa da, alal misali, Appalachians, ƙananan tsaunuka a cikin Amurka da Kanada. Daga baya har yanzu, sauran babbar nahiyar Gondwana ta matsa gaba zuwa arewa kuma ta yi karo da Laurussia. Ta haka ne aka kafa babbar nahiyar Pangea. Pangea ta kasance abin da ake kira supercontinent saboda ita ce kawai nahiyar a lokacin.
Ta yaya abubuwa masu rai suka samo asali a cikin Palaeozoic?
A farkon Palaeozoic shine Cambrian. A lokacin, dabbobin suna rayuwa ne kaɗai a cikin ruwa. Ya fi soso, murjani, katantanwa, da cephalopods. An riga an sami dabbobin farko waɗanda ke da kwarangwal ko harsashi. Furen ya fi iyakance ga algae. Ƙasar ta kasance babu tsiro.
A cikin lokaci na gaba, Ordovician, dabbobin ƙasa na farko, da tsire-tsire sun bayyana a kusa da bakin teku. Waɗannan galibin masu amphibians ne, watau dabbobin da suke rayuwa wani ɓangare a cikin ruwa da wani ɓangare a ƙasa. Akwai kuma dabbobin farko masu idanu. Musamman a cikin dabbobin Devonian da tsire-tsire suna yaduwa a cikin ƙasa, musamman kwari. Amma kuma da yawa sabbin nau'ikan sun fito a cikin teku. Waɗannan sun haɗa da, misali, kakannin sharks na yau.
Na farko dabbobi masu rarrafe sun bayyana a kan ƙasa a lokacin Carboniferous. Dabbobi sun ajiye ƙwai a ƙasa. Akwai manyan kwari kamar katon mazari. An riga an rufe babban yanki na saman duniya da daji. A zamanin Permian, yawancin dabbobin ruwa na wancan lokacin sun bace. A ƙasa, duk da haka, rayuwa ta ci gaba da haɓaka. Dabbobi masu rarrafe sun fara rarrabuwa zuwa masu ciyawa da masu cin nama. Daga cikin shuke-shuke, akwai na farko conifers.
A ƙarshen Permian, shekaru miliyan 250 da suka wuce, an sami canjin yanayi mai tsanani. An yi ta ne sakamakon mummunar fashewar aman wuta a Siberiya a yau. Sakamakon ya kasance mafi girman ɓarna a tarihin halitta zuwa yau. Sau biyu nau'in nau'ikan nau'ikan sun ɓace kamar lokacin da dinosaur suka ɓace shekaru miliyan 65 da suka gabata.