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Extinction

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99% of all species that ever lived are now extinct...


Extinctions


...and their fossils are preserved in layers that are strictly ordered chronologically. Nowhere do you find fossils that are out of place! Never are the fossils of mammals found with early reptiles, nor are amphibians found with the earliest trilobites. If a fossil were found out of place, it would be a scientist's dream come true. Their reputation would be made. But, so far no one has found a fossil that is out of place anywhere!


Extinctions


Species become extinct all the time, but periodically mass extinctions destroy large numbers of species in a short time.


  • The earth's geologic history has been punctuated by five massive extinctions. In scientific terms a "mass extinction" can be described as follows:
    A mass extinction is any substantial increase in the amount of extinction (i.e., lineage termination) suffered by more than one geographically widespread higher taxon during a relatively short interval of geologic time, resulting in an at least temporary decline in their standing diversity [numbers of species].
    - Sepkoski (in Donovan, 1989)

    In other words, mass extinctions rapidly affect many kinds of living things and are very widespread or even global in extent.
    Mass Extinctions An Ongoing Process


    Extinctions


  • Global Biodiversity Assessment
    The Global Biodiversity Assessment (GBA) is an independent, critical, peer reviewed scientific analysis of the current issues, theories and views regarding the main aspects of biodiversity. It provides an analysis of a wide range of biological and social science issues related to biodiversity.


    Extinctions

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