Kwixesha lePaleozoic sifumana amaxesha aliqela. Owesithathu kubo ngu Ixesha leSilurian. Ime phakathi kwe Ixesha le-Ordovician kunye Ixesha le-Devoni. Olunye lweempawu zayo eziphambili kukusebenza kwejografi okunobume beentaba ezinkulu. Malunga ne Izilwanyana zaseSilurian Sikwafumana uguquko olukhulu lweentlobo ezininzi zezilwanyana kwinqanaba lokwahlukahlukana. Eli xesha lexesha lalilawulwa ngesixa esikhulu sotshintsho kuzo zonke izilwanyana.
Ke ngoko, siza kulinikela eli nqaku ukuba likuxelele zonke iimpawu kunye nokuvela kwezilwanyana zaseSilurian.
Ixesha leSilurian
Ixesha leli xesha lalimalunga neminyaka ezizigidi ezingama-25. Iqale malunga nezigidi ezingama-444 kwiminyaka eyadlulayo kwaye yaphela malunga ne-419 yezigidi zeminyaka eyadlulayo. Kwakuyixesha elide ukusuka kwindawo yokujonga komhlaba. Ngalo lonke elixesha ukwenziwa kweenkqubo zeentaba esizaziyo namhlanje njengeentaba zeAppalachian zaseNtla Melika zenzeka.
Ngeli xesha umahluko omkhulu wobomi. Izityalo zokuqala zemithambo yaqala ukuvela kwaye izilwanyana zavela kwindaleko ebalulekileyo. Amakhorali kunye nearthropods ziphakathi kwezilwanyana eziguquke kakhulu. Kwakukho nenkqubo yokupheliswa ethathwa njengenqanaba elincinci. Ezi ziganeko zichaphazele ikakhulu izinto eziphilayo zaselwandle. Umzekelo, Isiqingatha seentlobo ze-trilobite saphela ngexesha le-Silurian.
Ngokubhekisele kwimozulu, iplanethi yazinza kancinci ngokubhekisele kumaqondo obushushu. Imozulu yaseSilurian yayishushu kakhulu. Ngamaxesha la maqhekeza omkhenkce awayesekhulile ngexesha elidlulileyo ayebekwe ngakwipali esemazantsi eplanethi. Kukho ubungqina bamathambo abonisa ukuba bekukho ixesha elininzi lezaqhwithi ngeli xesha. Emva kwezi ziganeko zemozulu, ubushushu bendalo esingqongileyo babonakala ngathi buyancipha. Ifikelele kwinqanaba lokuba yaqala ukupholisa imeko-bume kancinci kodwa ngaphandle kokufikelela kwinqanaba lexesha lomkhenkce. Ekupheleni kweli xesha Imozulu yaqala ukufuma ngakumbi kwaye yafudumala ngenani elikhulu lemvula.
Iintyatyambo kunye nohlaza
Njengoko besesitshilo ngaphambili, yonke into echaphazela ubomi, zombini izilwanyana kunye nezilwanyana, zenze utshintsho olukhulu ngeli xesha. Umnyhadala wolwandiso omkhulu wenzeka ngexesha lezilwanyana zaseSilurian apho ezinye iintlobo zinokuhluka kwaye ezinye zavela. Kwaye umsitho wokuphela unceda ekwenzeni ulungelelwaniso olutsha kwiintlobo zezinto eziphilayo.
Kwiflora sifumana isixa esikhulu se-algae kwizinto eziphilayo zaselwandle, ikakhulu ulwelwe oluhlaza. Ezi algae zazinomsebenzi wokulawula ibhalansi yendalo esingqongileyo kuba zazisisiseko sokuveliswa kweoksijini kunye nesiseko seetroniki. Ngeli xesha ixesha elibalulekileyo kuphuhliso lwezityalo lwenzekileyo. Kwaye kunjalo izityalo zokuqala ze-vascular zaqala ukuvela. Ezi zityalo zezo zineenqanawa zokuqhuba ezaziwa ngokuba yi-xylem kunye ne-phloem.
Ekuqaleni kweli xesha, umhlaba wawukude nommandla esiwubonayo namhlanje. Uninzi lokwahlukahlukana lwalusezindaweni zaselwandle. Izityalo zokuqala eziphuhliswe kwindalo ephilayo Bayacelwa ukuba bahlale kufutshane namanzi. Ngale ndlela banokubakho ngakumbi kunamanzi kunye nezondlo.
Izilwanyana zaseSilurian
Ukuphela kwexesha le-Ordovician kwabakho inkqubo yokupheliswa kobunzima echaphazela inani elikhulu lezilwanyana ezikhoyo. Njengoko besesitshilo ngaphambili, inkqubo yokutshabalala inceda izidalwa ezisaphilayo zenze uhlengahlengiso olutsha ukuze zisinde kwindawo entsha. Phakathi kweentlobo eziye zafezekiswa ukwahluka kunye nokuziqhelanisa nale mimandla mitsha sifumana iarthropods. IArthropods yayizilwanyana ezazilawula izilwanyana zaseSilurian.
Elinye lamaqela afumene indaleko ebalulekileyo. Malunga ne-fossil engama-425 ifunyenwe imele abantu abakule phylum. I-Trilobites inciphise uluhlu lwazo kunye nobuninzi ngenxa yokuphela kwexesha. Ngeli xesha I-Myriapods kunye ne-chelicerates zaqala ukubonakala okokuqala. Ezi zilwanyana zaqala ukusasazeka kuyo yonke imimandla yomhlaba.
Kwelinye icala, iimollusk nazo zazinokubuya okuthile. Phakathi kweemollusk ezazikho ngelo xesha sifumana iintlobo zeebivalve kunye neegastropods. Ezi zilwanyana zahlala elwandle zaza zaqhelana nale meko. Sikwafumana ii-echinoderms njengezilwanyana ezikwaziyo ukuziqhelanisa nasemva kokuphela kwexesha. Ngaphakathi kwee-echinoderms sifumana ii-crinoids eziye zanciphisa inani labo. Ezi crinoids zithathwa njengee-echinoderms zokuqala kwaye, ke, indala kwiplanethi.
Iqela leentlanzi liyakwazi ukubona ukwahlukahlukana. Ngexesha le-Ordovician ostracoderms zavela ikakhulu ngokungabinamhlathi. Ezi zilwanyana zithathwa njengezona zilwanyana zakudala zomqolo ekukho kuzo iingxelo zeefosili. Nangona kunjalo, ngexesha leSilurian ezinye iintlobo zeentlanzi zaqala ukubonakala. Phakathi kwezilwanyana zaseSilurian ngamanye amaxesha sifumana umhlathi owaziwa njengee-placoderms. Enye yeempawu zayo ezahlukileyo kukuba zineqokobhe ngaphambili kwimizimba yazo ukuzikhusela kumarhamncwa.
Ezinye iintlobo zeentlanzi ezavela ngexesha lezilwanyana zaseSilurian ziiacanthods. Ziyaziwa njenge-spiny shark kwaye ziyizinto eziphilayo ezifana ne-ostracoderms, intlanzi yeentlanzi. Kukho ukuthandabuza phakathi kwezazinzulu malunga nokuvela kwentlanzi. Abanye bathi bavele ngexesha lezilwanyana zaseSilurian, ngelixa abanye besithi bavela kwixesha elizayo.
Izilwanyana zaseSilurian: izixhobo zekorale
Iingqaqa zekorale zazibaluleke kakhulu kwizilwanyana zaseSilurian. Kuyaziwa ukuba izixhobo zokuqala zekorale zavela kwixesha elidlulileyo. Nangona kunjalo, kwakuleli xesha lokuba baqala ukwanda ngakumbi. Iindidi ezinxulunyaniswa nala matye anqabileyo ekorale zikwazile ukwandisa indawo yokuhambisa kunye nobuninzi. Kungenxa yokuba le coral reef ibanike yonke into abayifunayo ukuze baphile.
Ngombulelo kulungelelwaniso lweentlobo ezijikeleze iingqaqa zekorale, zazenziwe ziintlobo ezahlukeneyo. Phakathi kwezona ziqhelekileyo ukuqaphela sineziponji kunye nezinye iintlobo zeecrinoids eziliqela le-echinoderms.
Ndiyathemba ukuba olu lwazi ungafunda ngakumbi malunga nezilwanyana zaseSilurian.