Esikhathini se-Paleozoic sithola izikhathi eziningana. Owesithathu wabo yi Isikhathi se-Silurian. Itholakala phakathi kwe- Isikhathi se-Ordovician futhi i Isikhathi se-Devonia. Esinye sezici zayo eziyinhloko ukusebenza okukhulu kwe-geological okwakhiwa izintaba ezinkulu. Mayelana ne- Izilwane zaseSilurian Sithola nokuvela okukhulu kwezinhlobo eziningi ezingeni lezinto eziphilayo. Lesi sikhathi sesikhathi sabuswa ngenani elikhulu lezinguquko kuzo zonke izilwane.
Ngakho-ke, sizonikezela le ndatshana ukukutshela zonke izici nokuvela kwezilwane zaseSilurian.
Isikhathi se-Silurian
Isikhathi salesi sikhathi sasiyiminyaka engaba yizigidi ezingama-25. Yaqala eminyakeni eyizigidi ezingama-444 edlule futhi yaphela cishe eminyakeni eyizigidi ezingama-419 edlule. Kwakuyisikhathi esihle kakhulu ngokombono we-geological. Phakathi naso sonke lesi sikhathi ukwakheka kwezintaba esizaziyo namuhla kwenzeka, njenge Izintaba ze-Appalachian kusukela eNyakatho Melika.
Ngalesi sikhathi kwaba nokuhlukahluka okukhulu kwempilo. Izitshalo zokuqala ze-vascular zaqala ukuvela futhi izilwane zenza izinguquko ezibalulekile. Phakathi kwezilwane ezavela kakhulu kunamakhorali nama-arthropods. Kuphinde kwaba nenqubo yokushabalala ethathwa njengesezingeni elincane. Lezi zenzakalo zazithinta kakhulu izinto eziphilayo ezihlala olwandle. Ngokwesibonelo, uhhafu wezinhlobo ze-trilobite wanyamalala ngenkathi yeSilurian. Lokhu kushabalala kungafaniswa nezilwane zase-Ordovician.
Mayelana nesimo sezulu, iplanethi izinzile kancane ngokwezinga lokushisa. Isimo sezulu saseSiluria sasifudumele kakhulu. Phakathi nalesi sikhathi, izinguzunga zeqhwa ezakheke phakathi nenkathi edlule zazitholakala kakhulu ngasemaphethelweni aseningizimu yeplanethi. Kunobufakazi bemivubukulo obukhomba ukuthi kwaba nenkathi ende yeziphepho ngalesi sikhathi. Ngemva kwalezi zenzakalo zesimo sezulu, izinga lokushisa le-ambient libonakale lincipha. Kwafinyelela eqophelweni lokuthi indawo ezungezile yaqala ukuphola kancane, kodwa ngaphandle kokufinyelela ezingeni elidlulele leqhwa. Ekupheleni kwalesi sikhathi, Isimo sezulu siqale ukuba nomswakama futhi sishise ngenqwaba yemvula.
Izimbali nezimila
Njengoba sishilo ngaphambili, yonke into ehlobene nokuphila, kokubili izitshalo nezilwane, yaba noshintsho olukhulu phakathi nalesi sikhathi. Isigameko sokuqothulwa okukhulu kwenzeka ngesikhathi sezilwane zaseSiluria lapho ezinye izinhlobo zezilwane zakwazi ukuhlukahluka futhi ezinye izizukulwane zavela. Futhi umcimbi wokushabalala usiza ukudala ukujwayela okusha kwezinhlobo ezisaphila.
Ezitshalweni sithola inqwaba yolwelwe ezindaweni zasolwandle, ikakhulukazi ulwelwe oluluhlaza. Lezi algae zazinomsebenzi wokulawula ibhalansi yendawo ezungezile njengoba zaziyisisekelo sokukhiqiza umoya-mpilo kanye nesisekelo samaketanga okudla. Ngalesi sikhathi kwenzeka ingqophamlando ekuthuthukisweni kwezitshalo. Futhi yilokho izitshalo zokuqala zemithambo zaqala ukuvela. Lezi zitshalo yilezo ezinemikhumbi yokuqhuba eyaziwa njenge-xylem ne-phloem.
Ekuqaleni kwalesi sikhathi, isimo sezwe sasihluke kakhulu kulokho esikubona namuhla. Iningi lezinhlobonhlobo lalitholakala ezindaweni zasolwandle. Izitshalo zokuqala ezakhiwe ezindaweni eziphila emhlabeni kwakudingeka bahlale eduze kwezidumbu zamanzi, okwabavumela ukuba babe nokutholakala okukhulu kwamanzi nemisoco.
Izilwane zaseSilurian
Ekupheleni kwesikhathi se-Ordovician, kwaba nokuqothulwa okukhulu okwathinta inani elikhulu lezilwane ezikhona. Njengoba sishilo ngaphambili, inqubo yokuqothulwa isiza izinhlobo ezisindayo zikhiqize ukujwayela okusha ukuze ziphile endaweni entsha. Phakathi kwezinhlobo ezatholwa hlukanisa futhi uvumelane nalezi zindawo ezintsha esizithola kuma-arthropods. Ama-arthropods kwakuyizilwane ezazilawula izilwane zaseSilurian.
Ngenye yamaqembu abhekana nokuziphendukela kwemvelo okukhulu. Cishe kutholakale izinsalela ezingama-425 ezimele abantu bakule phylum. Ama-Trilobites anciphise ububanzi bawo nobuningi bawo ngenxa yesikhathi sokuphela. Ngalesi sikhathi Ama-myriapods nama-chelicerates aqale ukuvela okokuqala. Lezi zilwane zaqala ukusabalala kuzo zonke izindawo zomhlaba.
Ngakolunye uhlangothi, ama-mollusk nawo abe nokuziphendukela kwemvelo okuthile. Phakathi kwama-mollusk ayekhona ngaleso sikhathi sithola izinhlobo ze-bivalves nama-gastropods. Lezi zilwane zazihlala ngaphansi kolwandle futhi zazijwayelana nale ndawo. Siphinde sithole ama-echinoderms njengezilwane ezakwazi ukuzivumelanisa nezimo ngemva kwesikhathi sokushabalala. Ngaphakathi kwama-echinoderms sithola ama-crinoid, abantu bawo abagcina benciphile. Lawa ma-crinoid abhekwa njengama-echinoderms okuqala futhi, ngakho-ke, amadala kunawo wonke emhlabeni.
Iqembu lezinhlanzi likwazi ukubona ukuhlukahluka okuthile. Ngesikhathi se-Ordovician, kwavela ama-ostracoderms, abonakala ikakhulukazi ngokungabi nomhlathi. Lezi zilwane zibhekwa njengezilwane ezinomgogodla ezindala kakhulu okunamarekhodi ezinsalela. Nokho, phakathi nenkathi yamaSiluriya ezinye izinhlobo zezinhlanzi zaqala ukuvela. Phakathi kwezilwane zaseSiluria sithola izinhlanzi ezinemihlathi ezaziwa ngokuthi ama-placoderms. Esinye sezici zayo ezihlukile ukuthi zinegobolondo ngaphambili komzimba wazo ukuzivikela ezilwaneni ezizingelayo.
Ezinye izinhlobo zezinhlanzi ezavela ngesikhathi sezilwane zaseSiluria ama-acanthodians. Baziwa ngokuthi oshaka abangama-spiny futhi bayizinto eziphilayo ezifana nama-ostracoderms kanye nezinhlanzi ze-cartilaginous. Kukhona ukungabaza phakathi kososayensi mayelana nokubukeka kwezinhlanzi ze-cartilaginous. Abanye bathi bavela ngesikhathi sezilwane zaseSiluria, kanti abanye bathi bavela esikhathini sakamuva.
Izilwane zaseSilurian: izixhobo zamakhorali
Izixhobo zamakhorali zazibaluleke kakhulu ezilwaneni zaseSiluria. Kuyaziwa ukuthi izixhobo zamakhorali zokuqala zavela esikhathini esedlule. Nokho, Kwakuphakathi nalesi sikhathi lapho baqala khona ukwanda kakhulu. Izinhlobo ezihlotshaniswa nalezi zixhobo zamakhorali zikwazile ukwandisa indawo yazo yokusatshalaliswa nokuchichima. Lokhu kungenxa yokuthi lolu dwala lwamakhorali lwabanika konke abakudingayo ukuze baphile.
Ngenxa yokuguquguquka kwezinhlobo ezizungeze izixhobo zamakhorali, zazakhiwa izinhlobo ezahlukahlukene kakhulu. Phakathi kwezinto ezivame kakhulu ukugcinwa sinezipanji nezinye izinhlobo zama-crinoid eziseqenjini lama-echinoderms.
Ngiyethemba ukuthi ngalolu lwazi ungafunda kabanzi ngezilwane zaseSilurian.