When we talk about the Extra Terrestrial Life, we talk about possibilities of the presence of life. We breathe Oxygen. But how did the Dinosaurus lived and why couldn't they match with the changing environment and climate?
Aren't there any other chemical elements out there in other Planets by which the Living beings can live---some other WAYS of LIVING out there.
I think that they(the living beings in other planets) breathe(IF "they breathe") some other gases which supports life.