A cikin zamanin Paleozoic mun sami lokuta da yawa. Na ukunsu shine Lokacin Silurian. Tana tsakanin Lokacin Ordovician da kuma Lokacin Devonian. Ofaya daga cikin manyan halayenta shine tsananin tasirin ƙasa wanda samuwar manyan duwatsu yake dashi. Game da Falon Silurian Hakanan zamu sami babban juzu'in halittu da yawa a matakin bambancin halittu. An yi mulkin wannan lokacin tare da canje-canje da yawa a cikin duk fauna.
Saboda haka, zamu sadaukar da wannan labarin don gaya muku duk halaye da canje-canje na fauna na Silurian.
Lokacin Silurian
Tsawon wannan lokacin ya kai kimanin shekaru miliyan 25. Ya fara ne kimanin shekaru miliyan 444 da suka gabata kuma ya ƙare kimanin shekaru miliyan 419 da suka gabata. Lokaci ne mai kyau daga mahangar kasa. Duk tsawon wannan lokacin, tsarin tsaunukan da muka sani yau kamar tsaunukan Appalachian na Arewacin Amurka sun faru.
A wannan lokacin babban bambancin rayuwa. Tsire-tsire na farko na jijiyoyin jiki sun fara bayyana kuma dabbobi sun sami gagarumin canji. Murjani da jijiyoyin jiki suna daga cikin dabbobin da suka samu ci gaba sosai. Hakanan akwai aikin halakarwa wanda aka ɗauka azaman ƙaramin digiri. Wadannan al'amuran sun shafi kwayoyin halittu a cikin mazaunan ruwa. Misali, rabin nau'in trilobite sun bace a zamanin Silurian.
Dangane da yanayin yanayi, duniyar ta dan daidaita sosai dangane da yanayin zafi. Yanayin Silurian ya kasance mafi dumi. A waɗannan lokutan kankarar da suka samu a lokacin da suka gabata sun fi kusa da gindin kudu na duniyar tamu. Akwai shaidar burbushin halittu da ke nuna cewa akwai lokacin babban hadari a wannan lokacin. Bayan wadannan abubuwan canjin yanayi, yanayin yanayin muhalli kamar yana raguwa. Ya kai irin wannan matakin da ya fara sanyaya muhallin ɗan amma ba tare da ya kai matuka ga zamanin kankara ba. A karshen wannan lokacin sauyin yanayi ya fara zama mai ɗumi da dumi tare da adadi mai yawa na hazo.
Flora da ciyayi
Kamar yadda muka ambata a baya, duk abin da ya shafi rayuwa, na fure da na dabbobi, sun sami babban canji a wannan lokacin. Babban taron fadadawa ya faru yayin fauna na Silurian inda wasu nau'ikan zasu iya yaduwa kuma sauran halittu suka samo asali. Kuma wannan lamari ne na ƙarewa yana taimakawa ƙirƙirar sababbin canje-canje ga rayayyun jinsunan.
A cikin flora mun sami adadin algae da yawa a cikin halittun ruwa, galibi koren algae. Waɗannan algae suna da aikin sarrafa daidaituwar yanayi tunda sun kasance ginshiƙin samar da iskar oxygen da kuma tushen sarƙoƙin trophic. A wannan lokacin lokaci mai muhimmanci a ci gaban shuka ya faru. Kuma hakane tsirrai na jijiyoyin farko sun fara bayyana. Waɗannan tsire-tsire sune waɗanda ke da tasoshin gudanarwa da ake kira xylem da phloem.
A farkon wannan lokacin, yanayin shimfidar wuri ya yi nesa da yanayin da muke gani a yau. Yawancin bambancin sun kasance a yankunan ruwa. Tsirrai na farko da suka bunkasa a cikin halittu masu rai na duniya an bukace su su kasance kusa da ruwa. Ta wannan hanyar zasu iya samun wadatar ruwa da abubuwan gina jiki.
Falon Silurian
A ƙarshen zamanin Ordovician akwai tsarin ɓarna da yawa wanda ya shafi adadi mai yawa na dabbobin da ke akwai. Kamar yadda muka ambata a baya, wani tsari na bacewa yana taimaka wa jinsunan da ke raye don samar da sabbin karbuwa don samun damar tsira da sabon yanayin. Daga cikin nau'ikan da aka samu haɓakawa da daidaitawa zuwa waɗannan sababbin mahalli mun sami arthropods. Abubuwan da aka tsara sune dabbobin da suka mallaki fauna na Silurian.
Yana daya daga cikin kungiyoyin da suka sami babban canji. An gano kusan burbushin tarihi guda 425 wadanda suke wakiltar mutanen wannan kwayar halittar. Trilobites sun rage yanki na rarrabawa da yalwa saboda lokacin ƙarewa. A wannan lokacin Myriapods da chelicerates sun fara bayyana a karon farko. Wadannan dabbobin sun fara yaduwa a duk yankuna na duniya.
A gefe guda, maƙallan ma sun ɗan dawo. Daga cikin mollusks da suka wanzu a wancan lokacin muna samun jinsunan bivalves da gastropods. Waɗannan dabbobin sun zauna a bakin teku kuma sun dace da wannan yanayin. Hakanan zamu sami echinoderms azaman dabbobi waɗanda suka sami damar daidaitawa bayan lokacin ƙarewa. A cikin echinoderms mun sami crinoids wanda ya ƙare da rage yawan su. Wadannan crinoids ana daukar su azaman farkon halittu kuma, saboda haka, mafi tsufa a duniya.
Ungiyar kifin za a iya lura da wasu abubuwa daban-daban. A lokacin Ordovician zamanin ostracodererms sun bayyana musamman halayen rashin ciwon muƙamuƙi. Wadannan dabbobi ana daukar su tsofaffin kasusuwan tarihi wadanda akwai bayanan kasusuwan tarihi. Koyaya, yayin zamanin Silurian wasu nau'ikan kifaye sun fara bayyana. Daga cikin fauna na Silurian wani lokaci muna samun muƙamuƙin da aka sani da placoderms. Daya daga cikin siffofinsa na daban shine suna da kwalliya a gaban jikinsu don kare kansu daga masu lalata su.
Sauran nau'ikan kifaye waɗanda suka tashi yayin fauna na Silurian sune hanyoyin. An san su da suna spiny sharks kuma kwayoyin halitta ne kama da ostracoderms, kifin guringuntsi. Akwai shakku tsakanin masana kimiyyar game da bayyanar kifin mai guringuntsi. Wasu suna cewa sun bayyana yayin fauna na Silurian, yayin da wasu ke da'awar cewa sun bayyana a cikin wani lokaci na gaba.
Silurian fauna: murjani
Kogin murjani na da mahimmancin gaske a cikin fauna na Silurian. An sani cewa farkon murjani ya bayyana a lokacin da ya gabata. Koyaya, a wannan lokacin ne suka kara fadada. Jinsunan da ke hade da waɗannan maɓuɓɓugan murjani sun sami damar haɓaka yanki na rarrabawa da yalwa. Wannan saboda saboda wannan babban murjani ya ba su duk abin da suke buƙata don rayuwa.
Godiya da karbuwa daga jinsunan da ke kusa da murjani, an yi su ne da nau'ikan halittu daban-daban. Daga cikin abubuwan da aka fi sani don lura muna da fure-fure da sauran nau'ikan crinoids waɗanda ke cikin ƙungiyar echinoderms.
Ina fatan cewa tare da wannan bayanin zaku iya koyo game da fauna na Silurian.