Darwin’s claim was that earth’s species are dependents of ancestral species that were different from the species on earth in present day. He believes these changes are true because of decent with modification. A fossil can tell a lot about what the species of animal it was to how big and time period the animal was from. There were many men before Darwin who were thinking that animals were not just placed her on earth by god but have been here for a while. A man by the name of Nicholas Steno figured out that these rocks that look like sharks teeth are actually fossilized bones. Before Steno found this out, everyone thought that fossils fell from the sky. Another man by the name of Georges Cuvier found out that some species of animals that were once on earth are no longer here. He found a skeleton of an elephant in Italy, and at that time elephants were only found in Africa and India. When Darwin was on the Galapagos Islands when he found skeletons of animals that no longer exist, he found one of the first species of llamas and a giant sloth. All these are ancestors of animals found today. This showed Darwin that the animals on the earth now have changed in one way or another to survive for how long they have. This process is called natural selection. “The animals with the better attribute survive and pass on those traits that make more of that animal with the better traits is what causes animals to survive”(9 Weiner 7). Today, modern science shows us different ways animals are related by crossing fossil records. By looking at fossils you can see animal’s ancestors and how they could have changed to survive for how long they have. When Darwin is studying the finches on the Galapagos Islands he gathers a few from different islands and brings them home. Darwin shows the finches to a man named Gould who realizes the similar looking finches had small differences. He tells this to Darwin and he starts to think about common ancestry. If all the finches are closely related with a few minor changes from the ones from different islands. This must mean they have changed to adapt to their new habitat. The idea of changing to a new environment to survive is the theory of natural selection. A man named Galen was one of the first pe