mardi 19 novembre 2013

How do we know how large a percentage of all species that have gone extinct?

It is often said that 99.something percent of all species that have ever existed on Earth are extinct.



What is that number based on? As far from all organisms become fossilized, it is almost certainly the case that not all species have left remains (I'm not think of unicellular species, but of multicellular ones). So how did the estimate end up where it did?





via JREF Forum http://forums.randi.org/showthread.php?t=268827&goto=newpost

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