Answer:
The fittest organism survive and produce.
For the answer to the question above, I think the answer is simply because <span>four legs characteristic is not special to mammals but the hair that is something more important and special characteristic of the mammals, that's why. I hope this helps
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Energy used since long time ago is a energy production system where the energy is joined with the new resources and alll of that turns into electric energy!<span />
CO2 traps heat in the atmosphere of the earth which leads to global warming because of the green house effect
