How many climates does the U.S. have?

How can we use fossils to tell us about past climates on the Earth?

• Answer:

  Just as the other answerers said; morphology (bone structure usually) of a fossil is typically how paleontologists infer climate from fossils. If an organism had a similar morphology as something that presently exists in a warm climate, we can be pretty sure that it also lived in a warm climate. However, there are other ways. I did my senior thesis on foraminifera which are tiny amoeba-like creatures with shells. They live in the oceans and form these shells out of calcium, carbon and oxygen, (calcium carbonate or CaCO3) they get the oxygen atoms from the water around them. When they die the shells fall to the ocean floor and get buried. If, millions of years later, a scientist collects these shells, they can do an analysis of the relative ion levels of the oxygen. These oxygen ratios are related to temperature, thus by knowing the right equations we can get a fairly precise temperature reading for the oceans millions of years ago, which is more accurate than a temperature range from morphology. Scientists can use other elements, including carbon, from various sources to give a more complete picture of the Earth at the time of interest. I hope this helps a litte and didn't just confuse you more! Basically there are more ways to tell climate than just bones.