La Isikhathi se-Oligocene kwaba ngowesithathu nowokugcina ezinkathini ezakha inkathi yePaleogene yenkathi ka I-Cenozoic. Lesi yisikhathi lapho iplanethi yaba nezinguquko eziphawulekayo mayelana nezidalwa eziphilayo kanye ne-geology. I Izilwane ze-Oligocene yakwazi ukuchuma ngenxa yoshintsho oluyisisekelo lwesimo sezulu olwadala izimo ezikahle ukuze izilwane nezitshalo zichume.
Kulesi sihloko sizokutshela ngazo zonke izici nokuvela kwezilwane zase-Oligocene.
Isikhathi se-Oligocene
Le nkathi yaqala cishe cishe iminyaka eyizigidi ezingama-34 futhi yaphela cishe eminyakeni eyizigidi ezingama-23 edlule. Sonke lesi sikhathi iplanethi yathola izinguquko ezibonakalayo. Isimo sezulu sabamba iqhaza elibalulekile ekuthuthukiseni izitshalo nezilwane. Lezi zinguquko kwiplanethi zidale ukuthi izilwane kudingeke ziphinde zisabalalise umhlaba wonke.
I-Oligocene kube yisikhathi esihehe ochwepheshe ekutadisheni kwesikhathi se-geological kwazise banikele isikhathi esanele nomzamo ukuze bakwazi ukucacisa izinto ezifihliwe kakhulu. Isikhathi se-Oligocene cishe siyiminyaka eyizigidi eziyi-11 futhi, ngalesi sikhathi, ukunyakaza kwamapuleti ama-tectonic kwaqhubeka, kwafinyelela izikhundla ezifanayo nalezo abanazo namuhla.
Izilwane ze-Oligocene zidume ngokuthi zaziwa njengenkathi yezilwane ezincelisayo. Futhi iqembu lezilwane ezincelisayo yilona elathola ukuhlukahluka okukhulu nokuhlukahluka phakathi nalesi sikhathi. Ngenxa yokuthuthukiswa nokwanda kwezilwane, kwakhiwe izingxenye ezingaphansi ezaziwayo njengamagundane nama-canids. Okugqame kakhulu kwi-geology yalesi sikhathi yi-Laramide orogeny ne-Alpine orogeny.
Ngokuqondene nesimo sezulu, izimo ezaziphawula lesi sikhathi zazidlulele kakhulu. Yayibonakala ngamazinga okushisa aphansi kakhulu ayegcina izigxobo zimbozwe yiqhwa. Amanye ama-ecosystem ashintshwe ukwehla kwezinga lokushisa lomhlaba. Ake siyibheke kangcono impilo.
Flora
Izimbali zase-Oligocene zibonakala ikakhulukazi ngamahlathi e-coniferous ayedlangile kanye namahlathi ahlabayo. Lawa mahlathi alungiselelwe ukukwazi ukusinda emazingeni okushisa aphansi. Ama-Angiosperms aqala ukusakazeka enanini elikhulu lezindawo zokuhlala, kuba umpetha omkhulu. Ngaphezu kwalokho, ukuziphendukela kwemvelo kwayo kungaqondwa kangcono ngokucabangela umongo wezilwane ze-Paleogene kanye nomthelela wawo ekuziphendukeleni kwezilwane ezincelisayo.
Ngenxa yesimo sezulu esibanda kakhulu, ukwehla kwamahlathi ashisayo kwabonakala, okwathathelwa indawo izitshalo ze-herbaceous kanye nezindawo ezinotshani. Izinhlobo ezihlukahlukene zezitshalo kwadingeka zibhekane nesenzo sokuklama kwezilwane ezidla kuzo. Ake sihlaziye ukuthi ziyini lezi zilwane.
Izilwane ze-Oligocene
Izilwane zase-Oligocene zibonakala ngokuba namaqembu amaningi ezilwane akwazile ukwehlukahlukana futhi achuma naphezu kwezimo zezulu ezitholakale kuzo. Kula maqembu ezilwane ezahlukahlukene kakhulu sithola izinyoni, izilwane ezihuquzelayo nezilwane ezincelisayo. Abanye ososayensi babiza izilwane zase-Oligocene ubudala bezilwane ezincelisayo. Kumayelana nesikhathi senkathi yeCenozoic ukuthi yini enye engakhula ngokuya ngezilwane ezincelisayo.
Kwavela inani elikhulu lezinhlobo ezintsha zezilwane ezincelisayo, kuhlanganise namagundane, ama-canids, ama-primates nama-cetaceans. Ake sihlaziye ngayinye yazo.
Ama-Rodents
Ngaphakathi kokulandelana kwamagundane sithola iqembu eliningi kakhulu lezilwane ezincelisayo ezakhula ngesikhathi sezilwane ze-Oligocene. Isici sabo esasisiza ukubahlukanisa kwabanye kwakungama-incisors abukhali kakhulu asetshenziswa kaningi. Enye yazo ukuluma izilwane ezidla ezinye noma ukuququda izinkuni. Umndeni owaziwa kakhulu wamagundane e-Oligocene kwakuyi-Eomyidae. Zazifana nezingwejeje zanamuhla kodwa ezinomzimba omncane kanye nemikhuba ye-arboreal. Ukuze ufunde kabanzi mayelana nokuvela kwalezi zilwane ezincelisayo, ungabheka isihloko sethu esithi.
Iziboshwa
Ziyiqembu lezilwane ezincelisayo ezibonakala ngokuba neminwe emihlanu emaphethelweni azo. Enye yezinzuzo eziyinhloko zalezi zinkawu ngaphezu kwezinye izilwane ezincelisayo isithupha sazo esiphikisayo. Ngaphezu kwalokho, banezinyawo ze-plantigrade ezivumela ukuthi zisekele yonke indawo yonyawo lapho zihamba. Iphethini yabo yezinyo ijwayelekile futhi ayikhethekile kakhulu. Ama-primates angabonwa kaningi ngalesi sikhathi kwakuyi-lemur ne-tarsier. Ukuze uthole ukwaziswa okwengeziwe mayelana lemurs, ungabheka isihloko sethu isimo sayo samanje nezinsongo.
I-tarsier ingumzala we-tarsier, enosayizi omncane ocishe ube ngamasentimitha ayi-10. Izici zabo eziyinhloko ukuthi zinamehlo amakhulu ezivumela ukuthi zivumelanise umbono wazo nobumnyama. Banokudla kwezinambuzane ngokuphelele futhi bachitha isikhathi sabo esiningi bemisiwe emagatsheni ezihlahla.
Ngakolunye uhlangothi, I-lemur iyi-primate engaba nobukhulu obuhlukahlukene kuye ngezinhlobo ezingaphansi. Esinye sezici zayo eziphawulekayo umsila wayo omude. Ngokuvamile lo msila mude kunomzimba wonke. Amehlo azo makhulu futhi azivumela ukuthi zibone ebumnyameni. Abayihlukanisi kahle imibala, nakuba bekwazi ukuhlukanisa izimo.
Izilwane ze-Oligocene: ama-canids
Ngaphakathi kwamaswidi bangamalungu eqembu lezimpisi nezinja. Isici sayo esiyinhloko ukuba nomzimba onosayizi omaphakathi nokuhamba okusekelwe ezihlokweni zezinzwane zayo. Ziyizilwane ezidla inyama futhi eziningi zazo ziyizilwane ezidla ezinye. Bavela e-Eocene futhi kamuva bahlukahluka. Ukuziphendukela kwemvelo kwalezi zilwane ezincelisayo ezidla inyama maqondana nesimo sezulu kungaqondwa kangcono ngokufunda nge umthelela we-Ice Age.
AmaCetaceans
Iqembu lezilwane ezincelisayo elikwazile ukuzivumelanisa kakhulu nempilo yasolwandle. Izici zayo eziyinhloko ukubekwa phambili kwemboni zangaphambili ukuze zikwazi ukuba amaphiko. Izimpiko zazo zangemuva zinyamalele ngokuhamba kwesikhathi. Ukuphefumula kwabo kungamaphaphu, ngakho-ke kufanele bavame ukuphakama phezulu ukuze bathathe umoya.
Ngesikhathi sezilwane zase-Oligocene esinye sezilwane ezincelisayo zomhlaba ezinkulu kakhulu ezithuthukisiwe. Kuyaziwa njengeParaceratherium. Kwakunezilinganiso ezilinganisiwe ze- icishe ibe ngamamitha ayi-8 ukuphakama namamitha ayi-7 ubude. Kwakuyizilwane ezidla utshani ezinomuzwa wokuhogela okhule kahle kakhulu. Babengenabo nhlobo ubungane, kodwa kunalokho babephila bodwa. Ngokusobala babelwa bodwa ngokungqubuzana amakhanda, bevikelwe amathambo ogebhezi ayeminyene kakhulu kunokwejwayelekile.
Ngiyethemba ukuthi ngalolu lwazi ungafunda kabanzi ngezilwane zase-Oligocene.
