Cambrian Stage 4

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The fourth age of the Cambrian period (the time when the fourth stage of the Cambrian system, ie. succession of rock, was laid down) does not yet have an official (ICS) name, but it is informally known as the Botomian after the [[Siberia]]n-[[Kazakhstania]]n stage corresponding to its earlier part (its later part corresponds to the Toyonian).
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The fourth age of the Cambrian period (the time when the fourth ''stage'' of the Cambrian ''system'', ie. succession of rock, was laid down) does not yet have an official (ICS) name, but it is informally known as the Botomian after the [[Siberia]]n-[[Kazakhstania]]n stage corresponding to its earlier part (its later part corresponds to the Toyonian).
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Relative to later ecosystems, the Cambrian ecology was extremely delicate. This may be due to the fact that diveristy was very low, compared to modern ecosystems, and so environmental disruptions could easily wreak havoc (we are witnessing the groundworl of what may well be a similar disaster today - human stupidity and short-sightedness means that large areas of wilderness and biodiversity are being destroyed, to make way for extensive fields of ecologically vulnerable monocultures.)
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Relative to later ecosystems, the Cambrian ecology was extremely delicate. This may be due to the fact that diversity was very low, compared to modern ecosystems, and so environmental disruptions could easily wreak havoc (we are witnessing the groundwork of what may well be a similar disaster today - human stupidity and short-sightedness means that large areas of wilderness and biodiversity are being destroyed, to make way for extensive fields of ecologically vulnerable monocultures.)
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The Botomian witnessed a mass extinction that may have been even more severe than the end Permian extinction, in terms of absolute percentages of species lost. Some 83% of genera of hard-shelled or -bodied animals did not survive into the [[Middle Cambrian]]. However, relative to the rest of the Cambriabn this wasn't so bad. The Cambrian background extinctions between stages was about 40%, compared with about 5% in the Permian. So the Permain extinction was ten times the normal rate whereas the Botomian extinction rate was only twice the background rate.
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The Botomian witnessed a mass extinction that may have been even more severe than the end Permian extinction, in terms of absolute percentages of species lost. Some 83% of genera of hard-shelled or -bodied animals did not survive into the [[Middle Cambrian]]. However, relative to the rest of the Cambrian this wasn't so bad. The Cambrian background extinctions between stages was about 40%, compared with about 5% in the Permian. So the Permain extinction was ten times the normal rate whereas the Botomian extinction rate was only twice the background rate.
MAK020515, checked ATW040707, wikified HAJ090222
MAK020515, checked ATW040707, wikified HAJ090222

Latest revision as of 20:21, 9 September 2009

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