All living things on earth can be grouped into a foodchains.
elephant
Above all, that we're all related. Every single living thing uses the same genetic codes.
No, if the Earth was destroyed by an asteroid we would not be living today.
All living things on Earth contain carbon in that most of the molecules in us include carbon atoms. Dinosaurs were living creatures and are like all living creatures today in this respect.
A person or persons with that name living on Earth today.
singled cells
We get food and clear water from nature, and you get various types of living plants and animals, and nature is mostly about natural things which can be still found today.
there are about 1,500 tigers to 3,600 tigers still living on earth today
there are just over 6 billion people living on earth today
There are over Seven (7) Billion people living in the world (Earth) today.
There are thousands of wild dogs that are living today. These dogs can be found in almost all locations on Earth.
You have that the wrong way round, LIVING things have changed Earth's atmosphere to make it suitable for them. When Earth first came into being, the atmosphere was NOT like it is now, it could not sustain the life that exists today. Over Geological time tiny bacterial organisms generated the Oxygen that we have in our air today, and altered the whole environment of the planed in doing so. Thus the driving factor is LIFE not the atmosphere.