Causes and Consequences of Species Extinctions
نویسندگان
چکیده
The five largest mass die-offs in which 50–95% of species were eliminated occurred during the Ordovician [490–443 million years ago (mya)], Devonian (417–354 mya), Permian (299–250 mya), Triassic (251–200 mya), and Cretaceous (146–64 mya) periods. Most recently, human actions espe cially over the past two centuries have precipitated a global extinction crisis or the ‘‘sixth great extinction wave’’ com parable to the previous five. Increasing human populations over the last 50,000 years or so have left measurable negative footprints on biodiversity.
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تاریخ انتشار 2009