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RE: Extinct Species
April 2, 2012 at 10:11 am
(April 2, 2012 at 8:30 am)Phil Wrote: Considering the average lifetime of a species is 5-10 million years and the first life appeared 3800 million years ago, I have no doubt whatsoever that extinct species are over 99%
The problem with assigning numbers is the concept of "species" is hard to apply to the much of the unicellular world where bacteria liberally swap genes wholesale. Fossil evidence is also very lacking for complex life prior to about 600 million years ago, although DNA evidence puts origin of many of the complex animal phylums at 700-900 million years ago. It's not clear if speciation would be rapid prior to evolution of predation around 540 million yesrs ago. Finally there is reason to think rates of extinction amongst higher land animals were substantially different prior to permian extinction.
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RE: Extinct Species
April 2, 2012 at 10:20 am
(This post was last modified: April 2, 2012 at 10:20 am by BoyWonder.)
(April 2, 2012 at 10:11 am)Chuck Wrote: (April 2, 2012 at 8:30 am)Phil Wrote: Considering the average lifetime of a species is 5-10 million years and the first life appeared 3800 million years ago, I have no doubt whatsoever that extinct species are over 99%
The problem with assigning numbers is the concept of "species" is hard to apply to the much of the unicellular world where bacteria liberally swap genes wholesale. Fossil evidence is also very lacking for complex life prior to about 600 million years ago, although DNA evidence puts origin of many of the complex animal phylums at 700-900 million years ago. It's not clear if speciation would be rapid prior to evolution of predation around 540 million yesrs ago. Finally there is reason to think rates of extinction amongst higher land animals were substantially different prior to permian extinction.
You can make it as difficult as you want, and go looking for problems, or you can make it easy: take any 100 million year period you like, any, and look at the extinctions and survivors. That 99% will hold in each and every epoch you care to select.
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RE: Extinct Species
April 2, 2012 at 10:27 am
Not true. We have no firm grounds to even count species for the 3.3 billion years before 540 million years ago. If average life span of a species is 5 million years, and did not simply change gradually into a daughter species, then only 95% ought to be extinct in 100 million years. If 10 million years, then 90%. if sizeable fraction of species are continuous evolving into daughter species and not just dying off leaving no descendants, then the rates would be lower.
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RE: Extinct Species
April 2, 2012 at 10:35 am
(April 2, 2012 at 10:27 am)Chuck Wrote: Not true. We have no firm grounds to even count species for the 3.3 billion years before 540 million years ago. If average life span of a species is 5 million years, and did not simply change gradually into a daughter species, then only 95% ought to be extinct in 100 million years. If 10 million years, then 90%. if sizeable fraction of species are continuous evolving into daughter species and not just dying off leaving no descendants, then the rates would be lower.
Chuck,
You are confusing phyletic extinction (pseudoextinction) and extinction.
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RE: Extinct Species
April 2, 2012 at 10:38 am
(April 2, 2012 at 10:27 am)Chuck Wrote: Not true. We have no firm grounds to even count species for the 3.3 billion years before 540 million years ago. If average life span of a species is 5 million years, and did not simply change gradually into a daughter species, then only 95% ought to be extinct in 100 million years. If 10 million years, then 90%. if sizeable fraction of species are continuous evolving into daughter species and not just dying off leaving no descendants, then the rates would be lower.
Wouldn't new species be a branch of the former one? The concept of "daughter" would be if a species literally evolved into another, but what we get is a species branching from the original one and, in some cases, replacing it as the dominant form thus making it extinct.
“That which is asserted without evidence, can be dismissed without evidence.”
― Christopher Hitchens
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RE: Extinct Species
April 2, 2012 at 10:40 am
(April 2, 2012 at 10:38 am)Styper Wrote: (April 2, 2012 at 10:27 am)Chuck Wrote: Not true. We have no firm grounds to even count species for the 3.3 billion years before 540 million years ago. If average life span of a species is 5 million years, and did not simply change gradually into a daughter species, then only 95% ought to be extinct in 100 million years. If 10 million years, then 90%. if sizeable fraction of species are continuous evolving into daughter species and not just dying off leaving no descendants, then the rates would be lower.
Wouldn't new species be a branch of the former one? The concept of "daughter" would be if a species literally evolved into another, but what we get is a species branching from the original one and, in some cases, replacing it as the dominant form thus making it extinct.
Getting back to the original question, the estimate on wikipedia is 99.9%.
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RE: Extinct Species
April 2, 2012 at 10:42 am
(April 2, 2012 at 10:40 am)Phil Wrote: (April 2, 2012 at 10:38 am)Styper Wrote: (April 2, 2012 at 10:27 am)Chuck Wrote: Not true. We have no firm grounds to even count species for the 3.3 billion years before 540 million years ago. If average life span of a species is 5 million years, and did not simply change gradually into a daughter species, then only 95% ought to be extinct in 100 million years. If 10 million years, then 90%. if sizeable fraction of species are continuous evolving into daughter species and not just dying off leaving no descendants, then the rates would be lower.
Wouldn't new species be a branch of the former one? The concept of "daughter" would be if a species literally evolved into another, but what we get is a species branching from the original one and, in some cases, replacing it as the dominant form thus making it extinct.
Getting back to the original question, the estimate on wikipedia is 99.9%.
Thanks. Although we can't have a real number due to lack of information that seems about right.
“That which is asserted without evidence, can be dismissed without evidence.”
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RE: Extinct Species
April 2, 2012 at 11:17 am
Close enough for all intents and purposes.
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RE: Extinct Species
April 2, 2012 at 11:57 am
(April 2, 2012 at 8:30 am)Phil Wrote: Considering the average lifetime of a species is 5-10 million years and the first life appeared 3800 million years ago, I have no doubt whatsoever that extinct species are over 99%
Why is it that a species can't last any longer than that?
"It is the mark of an educated mind to be able to entertain a thought without accepting it" ~ Aristotle
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RE: Extinct Species
April 2, 2012 at 11:59 am
(April 2, 2012 at 11:57 am)FallentoReason Wrote: (April 2, 2012 at 8:30 am)Phil Wrote: Considering the average lifetime of a species is 5-10 million years and the first life appeared 3800 million years ago, I have no doubt whatsoever that extinct species are over 99%
Why is it that a species can't last any longer than that?
Who said they can't?
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