These show anatomy that is in between earlier and later forms. The fossil record of horses in North America is quite rich. The fossil record that comes from this is made up of all the fossils that have been found to tell a story of the past and show the evolution of form over millions of years.įossil records with a lot of detail have been found for sequences of species in the evolution of whales and modern horses. Scientists figure out the age of fossils, or remains, and sort them all over the world to decide when the life forms lived in relationship to each other. This causes entire groups of living things to change because the parents pass on what helped them live to their children.įossils give strong evidence that livings things from the past are not the same as those found today because they show a progression of evolution. Evolution is when living things adapt over time to their environments in ways that help them live long enough to reproduce. Since the time of Darwin, what we know has become clearer and broader. A large part of Darwin's book, On the Origin of Species, found patterns in the world around us that make sense with evolution. When they look at every level of organization in living systems, biologists see the mark of past and present changes. The evidence for evolution is deep and far-reaching.

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