Amphibians â the comeback kings of evolution

[Dann Pigdon <dannj@alphalink.com.au>]

Amphibians â the comeback kings of evolution
08 January 2007, NewScientist.com news service
Catherine Brahic 


...a look at their latest evolutionary tree reveals that amphibians have a 
remarkable capacity to bounce back from environmental changes, says Kim 
Roelants of Vrije University in Brussels, and colleagues. 

...The work revealed that todayâs amphibians have three common ancestors, 
which arose around 350 million years ago. That trio suddenly branched out 
between 250 million and 225 million years ago â around the time of a 
global mass extinction at the end of the Permian Period, when some 95% of 
all life forms had disappeared from the face of the planet. The three 
eventually gave rise to frogs and toads, salamanders, and caecilians 
(snake-like animals that live underground), respectively. This boom, called 
explosive radiation, gave rise to the gamut of amphibians we know today. 

Another two booms happened around the Cretaceous-Tertiary extinction, about 
65 million years ago. In total, approximately 86% of frog species alive 
today and more than 81% of salamander species descend from just five 
amphibian species that survived this mass extinction 65 million years ago... 

Read more at:
http://www.newscientist.com/article/dn10910-amphibians--the-comeback-kings-o 
f-evolution-.html 

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Dann Pigdon
GIS / Archaeologist         http://www.geocities.com/dannsdinosaurs
Melbourne, Australia        http://heretichides.soffiles.com
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