Kashimarana

Kashimarana - jinsin dabbobin da suka mutu, suna da alaƙa da tetrapods (ƙananan ƙafa huɗu na ƙasa). An samo shi ne azaman dutse a gabashin Greenland na Late Devonian lokacin shekaru miliyan 370 da suka gabata. Kodayake ana kiran Ichthyostegus a matsayin "tetrapods" saboda gabobin da yatsun hannu, ya kasance jinsin "dadadden" na asali fiye da tetrapods na kambi na gaskiya, kuma ana iya kiransa da madaidaici stegocephalic ko kara tetrapod.

Asalin jinsin da bayanin

Hotuna: Ichthyostega

Ichthyostega (daga Girkanci "rufin kifi") ɗan adam ne na farko daga ƙirar tetrapodomorphs waɗanda suka rayu a ƙarshen zamanin Devonian. Ya kasance ɗayan farkon kasusuwa huɗu masu gaɓoɓin da aka samo a cikin burbushinsu. Ichthyostega ya mallaki huhu da gaɓoɓi waɗanda suka taimaka mata kewaya cikin zurfin ruwa cikin fadama. Ta hanyar tsari da halaye, ba a ɗauke shi memba na gaskiya na ƙungiyar ba, tun da farkon amphibians na zamani (membobin ƙungiyar Lissamphibia) sun bayyana a lokacin Triassic.

Bidiyo: Ichthyostega

Gaskiya mai ban sha'awa: An bayyana jinsuna huɗu asali kuma an bayyana jinsin na biyu, Ichthyostegopsis. Amma ci gaba da bincike ya nuna samuwar wasu amintattun jinsuna guda uku gwargwadon yanayin kwanyar da kuma hade da abubuwa daban-daban guda uku.

Har zuwa lokacin da aka gano wasu farkon stegocephals da kifi masu alaƙa a ƙarshen karni na 20, Ichthyostega ya kasance shi kaɗai ne wanda aka samo a matsayin burbushin halittu tsakanin kifi da tetrapods, yana haɗuwa da kifi da tetrapods. Wani sabon binciken da aka gudanar ya nuna cewa tana da tiyatar da ba a saba gani ba.

A al'adance, Ichthyostega yana wakiltar ajujuwan halittu masu raunin tetrapods, saboda haka yawancin masu binciken zamani basa sanya shi a matsayin kakannin jinsunan zamani. Nazarin Phylogenetic ya nuna cewa ichthyosteg hanya ce ta tsaka-tsakin tsaka-tsakin tsaka-tsakin tetrapods. A cikin 2012, Schwartz ya tattara bishiyar juyin halittar farkon stegocephals.

Bayyanar abubuwa da fasali

Hotuna: Yaya ichthyostega yake?

Ichthyostega tsayinsa ya kai kusan mita daya da rabi kuma yana da ƙaramar ƙaran dorsal a gefen jelar. Wutsiyar kanta ta mallaki wasu nau'ikan goyan bayan abubuwa masu yawa irin na wutsiyar wutsiyar da ake samu a cikin kifi. Sauran fasalulluka wadanda suka ci gaba a cikin kasusuwa na farkon ruwa sun hada da dan karamin bakin bakinsa, kasancewar wani kashin preopercular a yankin kunci wanda yake matsayin wani bangare na kwazazzabo, da kananan sikeli masu yawa a jiki. Abubuwan haɓaka na yau da kullun waɗanda ke da alaƙa da tetrapods sun haɗa da jerin ƙasusuwa masu ƙarfi da ke tallafa wa gaɓoɓin jiki, rashin ƙoshin lafiya da haƙarƙari masu ƙarfi.

Gaskiya mai ban sha'awa: Ichthyostega da danginsa suna wakiltar siffofin da suke da ɗan ci gaba fiye da na ruwa na Eusthenopteron, kuma da alama suna kusa da layin juyin halitta wanda ke haifar da tetrapods na farko a doron ƙasa.

Babban sanannen yanayin kwarangwal na ichthyosteg shine iyakar abin da haƙarƙarin ya haɗu. Aƙarin hakarkarin hanji ɗaya na iya haɗuwa da haƙarƙarin haƙarya uku ko huɗu, yana yin "corset" mai kama da ganga a jiki. Wannan yana nuna cewa dabbar ba zata iya lankwasa jikinta daga gefe yayin tafiya ko iyo ba. Abun bayanan baya kasance abin ƙyama, amma jijiyoyin jijiyoyin suna da shahararren zygapophyses.

Ana iya ɗauka cewa dabbar ta motsa sosai sakamakon jujjuyawar juzu'i fiye da lokacin tafiya na al'ada. Wataƙila an yi amfani da manyan goshin ne don jan dabbar a gaba sannan a murɗa yankin shugaban ƙasa don taƙaita bayanta. Limananan gaɓoɓin kafa sun ƙunshi wata gajeriyar mace mai kauri tare da babban flange da mai haɗawa da zurfin zurfin fossa.

Manyan, kusan tibiyon hudu da kuma gajeren fibula an daidaita su. Babban matsakaici da fibula sun hada da yawancin kasusuwa na idon sawun. Kyakkyawan samfurin da aka adana, wanda aka tattara a cikin 1987, ya nuna cikakken saiti na yatsu bakwai, ƙarami uku a gefen gaba da kuma cikakkun huɗu a baya.

A ina ne ichthyostega yake rayuwa?

Hotuna: Ichthyostega a cikin ruwa

An samo ragowar ichthyosteg a cikin Greenland. Kodayake ba a san ainihin nau'in jinsin ba, ana iya ɗauka cewa ichthyostegs mazaunan arewacin duniya ne. Kuma sun rayu cikin ruwan Tekun Atlantika da Arctic yanzu. Lokacin Devonian yana da yanayi mai ɗan dumi kuma, mai yiwuwa, babu kankara. Bambancin zafin jiki daga mahaɗan zuwa sandunan bai kai yadda yake a yau ba. Yanayin ya kuma bushe sosai, galibi tare da kima, inda yanayin ya fi bushewa.

Gaskiya mai ban sha'awa: Maimaitawar yanayin yanayin yanayin teku mai zafi yana ɗaukar kimanin 25 ° C a cikin farkon Devonian. Matakan Carbon dioxide sun ragu sosai a lokacin Devonian, yayin da binne sabbin gandun daji da aka fitar da carbon daga yanayi zuwa daskararre. Ana nuna wannan a tsakiyar lokacin Devonian ta sanyayar yanayin ƙwanƙwasawa zuwa 5 ° C. Marigayi Devonian yana da yanayin ƙaruwa da zafin jiki zuwa matakin daidai da farkon Devonian.

A waccan lokacin, babu wani ƙaruwa mai daidaito a cikin adadin CO² kuma yanayin yankuna yana ƙaruwa (kamar yadda yanayin zafi ya nuna). Kari akan haka, wasu shaidu da yawa, kamar rarraba shuke-shuke, suna nuni ne ga dumamar Marigayi Devonian. A wannan lokacin ne burbushin halittun da aka samo suna kwanan wata. Zai yiwu cewa an adana ichthyostegs a cikin zamanin Carboniferous na gaba. Ballantuwarsu na iya haɗuwa da raguwar zafin jiki a mazauninsu.

A wannan lokacin, sauyin yanayi ya shafi yawancin kwayoyin halittu a cikin reefs, microbes sune manyan kwayoyin halittar reef a lokacin dumi, kuma murjani da stromatoporoids sun taka rawar gani a lokutan sanyi. Dumamar ɗumi a ƙarshen Devonian na iya ba da gudummawa ma don ɓacewar stromatoporoids.

Yanzu kun san inda aka samo ichthyosteg. Bari muga me ta ci.

Menene Ichthyostega ya ci?

Hotuna: Ichthyostega

Yatsun ichthyosteg sun yi rauni sosai, kuma tsarin murdadden ya yi rauni, amma dabbar, ban da yanayin ruwa, tuni yana iya motsawa tare da yankunan ƙasar da ke da fadama. Idan muka yi la'akari da lokacin shaƙatawa na ichthyostega a cikin misalan kashi, to, 70-80% na lokacin da ta ci nasarar haɓakar ruwan, da sauran lokutan ta yi ƙoƙari ta mallaki ƙasar. Babban tushen abincin shi shine mazaunan tekun wancan lokacin, kifi, jirgin ruwa, da kuma yiwuwar tsire-tsire na ruwa. Matsayin teku a cikin Devonian gaba ɗaya ya kasance mai tsayi.

Har yanzu faunas na cikin ruwa sun mamaye ta:

• bryozoans;
• bambance bambancen da yalwa;
• gederellids mai ban mamaki;
• microconchids;
• crinoids masu kama da lily, duk da kamanninsu da furanni, suna da yawa;
• trilobites sun kasance suna gama gari.

Zai yiwu Ichthyostega ya ci wasu daga waɗannan nau'in. A baya, masana kimiyya sun danganta ichthyostega tare da bayyanar tetrapods a doron ƙasa. Koyaya, mai yiwuwa, ya tafi kan ƙasa na ɗan gajeren lokaci, kuma ya koma ruwa. Wanene daga cikin tsofaffin ƙananan ƙasashe ya zama ainihin mai gano ƙasa har yanzu ana iya gani.

A zamanin Devonian, rayuwa tana cikin tafiya cikin tsarin mulkin mallaka na ƙasar. Dazukan silus na silurian da dattin kwayar cuta a farkon lokacin sun haɗa da shuke-shuke na asali waɗanda suka ƙirƙiri ƙasashe masu jurewa na farko da maƙogwaro irin su mites, kunama, trigonotarbids da millipedes. Kodayake arthropods sun bayyana a duniya fiye da farkon Devonian, kuma kasancewar burbushin halittu irin su Climactichnites yana nuna cewa arthropods na duniya na iya bayyana tun farkon Cambrian.

Burbushin halittun farko da ya yiwu ya bayyana a farkon Devonian. An gabatar da bayanan tetrapod na farko azaman sawun burbushi a cikin lagoons masu zurfin ruwa na dandamali / shimfidar carbonate a lokacin Tsakiyar Devonian, kodayake waɗannan takun sawun an yi tambaya kuma masana kimiyya sunyi tunanin alamun ciyar da kifi. Duk wannan tsire-tsire masu saurin girma da fauna sun kasance tushen tushen abinci ga Ichthyosteg.

Fasali na ɗabi'a da salon rayuwa

Hotuna: inarshen Ichthyostega

An saita shekarun dabbar zuwa shekaru miliyan 370 kuma sun dace da lokacin Devonian. Ichthyostega shine ɗayan tsofaffin sanannun tetrapods. Saboda halayensa, wadanda suka hada da halaye na kifi da na amphibians, Ichthyostega yayi aiki a matsayin muhimmiyar kafa da kuma shaidar mahaifa ga ka'idar juyin halitta.

Gaskiya mai ban sha'awa: Oneaya daga cikin mafi kyawun gaskiyar game da ichthyosteg ba shine tana da ƙafafun kafa ba, amma cewa tana iya shan iska - aƙalla na ɗan gajeren lokaci. Koyaya, koda tare da wannan damar mai ban mamaki, mai yiwuwa ba ta daɗe sosai a ƙasa. Wannan saboda yana da nauyi sosai kuma ƙafafunsa ba su da ƙarfi don motsa ƙarfin jikinsa.

Gaban Ichthyostega ya bayyana da nauyi kamar haka kuma gaban goshin ya kasa faɗaɗa gabaɗaya. Rabon hatimin giwa shine kwatancin tsarin anatomical tsakanin dabbobi masu rai. Wataƙila Ichthyostega ya hau kan rairayin rairayin bakin teku masu motsi, yana motsa ƙafafun gaba a layi daya kuma yana jan gabobin baya da shi.

Dabbar ta kasa tabuka komai saboda yanayin gaban gabanta ba su da yanayin jujjuyawar da ake bukata. Koyaya, ainihin salon rayuwar Ichthyostega bai bayyana ba tukunna saboda abubuwan da yake da su.

Tsarin zamantakewa da haifuwa

Hotuna: Ichthyostegai

An yi amannar cewa ichthyostegs da danginta sun ɗan share lokaci suna laluben rana don ɗaga zafin jikinsu. Sun kuma koma cikin ruwa don suyi sanyi, farautar abinci, da haifuwa. Yanayin rayuwarsu yana buƙatar gaban goshi mai ƙarfi don cire aƙalla gaban daga ruwa, da ƙyamar ƙugu da kashin baya don tallafa musu, yin tanning a cikin cikinsu kamar kada mai zamani.

Gaskiya mai ban sha'awa: Ichthyostegs ya zama magabatan manyan rassa biyu na amphibians, sun banbanta da tsarin kwanyar da ƙafafu. A cikin Late Devonian, labyrinthodonts ya tashi. A waje, sun yi kama da kada ko salamanders. A yau, ɗaruruwan nau'ikan labyrinthodonts sun zama sananne, suna zaune a cikin gandun daji mai dausayi da koguna.

Ruwa ya zama dole ne ga ichthyostega, tunda ƙwai farkon tetrapods ba za su iya rayuwa a wajen ruwa ba, don haka haifuwa ba za ta iya faruwa ba tare da yanayin ruwa ba. Hakanan ana bukatar ruwa don tsutsa da kwayayen waje. Tun daga wannan lokacin, mafi yawan ƙasusuwan ƙasashen duniya sun haɓaka hanyoyi biyu na hadi na cikin gida. Ko dai kai tsaye, kamar yadda aka gani a cikin dukkanin amniotes da ampan amphibians, ko kuma kai tsaye ga masu salamanders da yawa, sanya spermatophore a ƙasa, sannan mace ta ɗaga.

Abokan gaba na ichthyosteg

Hotuna: Yaya ichthyostega yake?

Kodayake ba a sake gina ƙasan gaba ba saboda ba a same su cikin sanannun burbushin dabba ba, an yi imanin cewa waɗannan abubuwan haɗin sun fi na bayan dabbar girma. Masana kimiyya sunyi imanin cewa ta wannan hanyar ichthyostega ya motsa jikinsa daga ruwa zuwa ƙasa.

Da alama locomotion, wanda yake aiki ne na ɗabi'ar motsa jiki na tsarin musculoskeletal na jiki, yana wakiltar ɗan bambancin motsi ne kawai a ƙarƙashin ruwa ta amfani da haɗuwa da jela da ƙafafun kafa. A wannan halin, an yi amfani da ƙafafu musamman don wuce tsokoki ta cikin ambaliyar ruwa ta shuke-shuke na shuke-shuke.

Gaskiya mai ban sha'awa: Kodayake motsi na ƙasa yana yiwuwa, Ichthyostega ya sami ci gaba sosai don rayuwa cikin ruwa, musamman a lokacin matakan girma na rayuwarta. Ba safai yake tafiya kan tudu ba, kuma mafi kankantar girman kananan yara, wanda ya basu damar matsawa cikin sauki a kan tudu, bai yi aikin neman abinci ba a wajen ruwan, amma a matsayin wata hanya ce ta kauce wa wasu manyan masu cin nama har sai sun girma da yawa don kada su zama ganimar su.

Masana kimiyya suna jayayya cewa ci gaban ƙasa ya ba dabbobi kyakkyawan tsaro daga masu farauta, ƙarancin gasa don ganima, da wasu fa'idodin muhalli waɗanda ba a samu a cikin ruwa, kamar ƙwarin oxygen da kula da yanayin zafin jiki - wanda ke nuna cewa ƙananan gabobin ma suna dacewa da hali wani ɓangare na lokacin su daga ruwa.

Koyaya, bincike ya nuna cewa sarcopterygs sun kirkiro gabobin hannu masu kama da tetrapod wadanda zasu dace da tafiya sosai kafin tafiya ƙasa. Wannan yana nuna cewa sun saba da tafiya a kan ruwa karkashin kasa kafin su koma kasa.

Yawan jama'a da matsayin jinsin

Hotuna: Ichthyostega

Ichthyostega wani nau'in ne wanda ya dad'e da dad'ewa. Saboda haka, a yau yana da wahala a yanke hukunci kan yadda yawan Ichthyostega ya yadu a Duniya. Amma tunda burbushin halittu ne kawai aka samu a cikin Greenland, tabbas adadin mutane ba shi da wata mahimmanci. Wadannan dabbobi sun rayu a cikin wani mawuyacin lokaci. Wani babban halaka ya faru a farkon matakin ƙarshe na Devonian, fauna na ajiyar Famennian ya nuna cewa kimanin shekaru miliyan 372.2 da suka wuce, lokacin da duk kifin-agnatans, ban da heterostracic psammosteids, ba zato ba tsammani.

Late Devonian ya kasance ɗayan manyan abubuwa biyar na ɓacewa a tarihin rayuwar Duniya, kuma ya kasance mai tsattsauran ra'ayi fiye da irin wannan lamarin na ɓarna wanda ya rufe Cretaceous. Rikicin ɓarkewa na onabilanci da farko ya shafi al'ummar tekun kuma ya zaɓi ƙwayoyin ruwa-ruwa a cikin ruwa mai dumi. Babban mahimmin rukuni wanda ya sha wahala daga wannan abin da ya faru a cikin halakar shi ne magina manyan tsarukan ruwa.

Daga cikin kungiyoyin ruwan tekun da abin ya shafa sun hada da:

• brachiopods;
• ammonites;
• trilobites;
• akritarchs;
• kifi ba tare da muƙamuƙi ba;
• conodonts;
• duk placoderms.

Tsirrai na ƙasa da nau'ikan ruwa irin su kakanninmu masu tetrapod ba su da tasirin abin da ya faru na Late Devonian. Har yanzu ba a san dalilan bacewar nau'ikan halittu a Marigayi Devonian ba, kuma duk bayanin na ci gaba da hasashe. A cikin waɗannan yanayi saukarinna ya rayu kuma ya yawaita. Tasirin Asteroid ya canza saman Duniya kuma ya rinjayi mazaunanta.

Ranar bugawa: 08/11/2019

Ranar da aka sabunta: 09/29/2019 a 18:11