Their bone structure from fossils and their morphology
Scientists learn a few different things. Scientists learn new things very day.
they learn behavioral patterns of the animals.
Scientists can learn many things from fossils:What an ancient animal's bones looked likeWhat ancient plants looked likeHow an ancient animal's body might have lookedWhat kind of environment existed in that area millions of years agoHow animals and plants probably interacted millions of years ago
Their DNA
They don't, they guess.
Yes
so they can learn more things about it.
with technology
So that we can learn more about ancient earth.
There are a number of things that scientists study to learn about prehistory. This will include archaeological facts and fossil evidence which gives an explanation of how most things came into being.
An electron microscope is used to show a picture of things as small as atoms. It is useful to be able to actually see things that are invisible to our normal eyes. People are visual animals, and we learn most of our information by seeing. If scientists can see cells and atoms, it is easier for them to learn about them and study them.
They learn about diseases Take a chimp for example scientists use chimps so that they can discover about diseases that can spread to humans.