About 200 years ago a man named William Smith was building a large canal. As he dug into the earth, he 'noticed that there were fossils in the strata' and that 'each layer had its own kinds of fossils.' The layers showed how the plants and animals in the layers slowly evolved through time. There would be a certain kind of plant or animal in one layer but after time passed that animal or plant would die out and it wouldn't be found in the layers that were more recent. 'Reptiles were the ancestors of the first mammals, which were shrew-like creatures.' (That probably explains a lot.)'From these, all other mammals evolved'even human beings.' Ages 5-9