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Reason behind dinosaurs' extinction from the earth |
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Environment
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Written by Team Josh
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Monday, 28 April 2008 |
 US scientists have found the reason behind why dinosaurs' extinction from the earth and it is because they lack a heat-generating tissue present in them. Scientists have gone on to conclude that the absence of this tissue may have led to the extinction of dinosaurs.
All mammals have two kinds of adipose tissue – white and brown fat. White fat is used for storing energy-rich fuels, while brown fat generates heat.
While most mammals have a key gene called UCP1, which is responsible for the heat-generation function of brown fat, birds do not.
Researchers at New York Medical College found they could induce a specific type of stem cell in chicken embryos to produce differentiated cells that are structured and behave like brown fat.
These chicken cells could even activate a UCP1 gene if presented with one from a mouse.
The ability to produce brown fat evolved in a common ancestor of birds and mammals. But the ability to generate heat was lost in the group that gave rise to birds and lizards after it separated from the mammalian lineage.
Dinosaurs, which diverged from birds even later than lizards, also lacked brown fat and that lead to their extinction.
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