Scientists classify the different types of living things into groups called species .
For example, all people belong to a species called Homo sapiens . Humans are grouped with monkeys, apes, and lemurs into a larger group called Primates. The primates in turn are part of a still larger group, the Mammals, which includes all animals that feed their young with milk. Using this system of scientific names , all living things can be sorted into groups which make it easier for people all over the world to study and understand them. To find out what species of fossil they have found, researchers sort the specimens into groups based on similarities and differences between them.