জীবন: সংশোধিত সংস্করণের মধ্যে পার্থক্য
বিষয়বস্তু বিয়োগ হয়েছে বিষয়বস্তু যোগ হয়েছে
অসম্পাদনা সারাংশ নেই ট্যাগ: ২০১৭ উৎস সম্পাদনা |
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২৬৬ নং লাইন:
Extinction is the process by which a group of [[taxa]] or [[species]] dies out, reducing biodiversity.<ref>{{cite encyclopedia |title=Extinction – definition |url=http://encarta.msn.com/dictionary_1861609974/extinction.html |archiveurl=https://www.webcitation.org/5kwseRB80?url=http://encarta.msn.com/dictionary_1861609974/extinction.html |archivedate=1 November 2009 |deadurl=yes}}</ref> The moment of extinction is generally considered the death of the last individual of that species. Because a species' potential [[range (biology)|range]] may be very large, determining this moment is difficult, and is usually done retrospectively after a period of apparent absence. Species become extinct when they are no longer able to survive in changing [[habitat]] or against superior competition. In [[History of the Earth|Earth's history]], over 99% of all the species that have ever lived are extinct;<ref>{{cite web | url=http://palaeo.gly.bris.ac.uk/Palaeofiles/Triassic/extinction.htm | title=What is an extinction? | work=Late Triassic | publisher=Bristol University | accessdate=27 June 2012 }}</ref><ref name="Book-Biology">{{cite book |editor1=Kunin, W.E. |editor2=Gaston, Kevin |title=The Biology of Rarity: Causes and consequences of rare—common differences
|url=https://books.google.com/books?id=4LHnCAAAQBAJ&pg=PA110&lpg=PA110&dq#v=onepage&q&f=false|date=31 December 1996 |isbn=978-0-412-63380-5 |accessdate=26 May 2015 }}</ref><ref name="StearnsStearns2000">{{cite book |last=Stearns |first=Beverly Peterson |last2=Stearns |first2=S. C. |last3=Stearns |first3=Stephen C. |title=Watching, from the Edge of Extinction |url=https://books.google.com/books?id=0BHeC-tXIB4C&q=99%20percent#v=onepage&q=99%20percent&f=false |year=2000 |publisher=[[Yale University Press]] |isbn=978-0-300-08469-6|page=preface x |accessdate=30 May 2017 }}</ref><ref name="NYT-20141108-MJN">{{cite news |last=Novacek |first=Michael J. |title=Prehistory's Brilliant Future |url=https://www.nytimes.com/2014/11/09/opinion/sunday/prehistorys-brilliant-future.html |date=8 November 2014 |work=[[New York Times]] |accessdate=25 December 2014 }}</ref> however, [[mass extinction]]s may have accelerated evolution by providing opportunities for new groups of organisms to diversify.<ref>{{Cite journal |last=Van Valkenburgh |first=B. |date=1999 |title=Major patterns in the history of carnivorous mammals |journal=Annual Review of Earth and Planetary Sciences |volume=27 |pages=463–93 |doi=10.1146/annurev.earth.27.1.463 |bibcode=1999AREPS..27..463V}}</ref>
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===জীবাশ্ম===
{{Main article|জীবাশ্ম}}
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