摘要：Parasites are organisms of notoriously bad reputation. This is not surprising, as they benefit at the expense of their host organisms. Today, parasites are everywhere (living on both land and in water) and diverse (having representatives among bacteria, animals and plants). They have roamed on the Earth for hundreds of millions of years, adapting to various invertebrate and vertebrate hosts, including hominids and modern humans later on in the Cenozoic era. This indicates that parasites have achieved great evolutionary and ecological success. However, many issues concerning parasites and parasitism—such as its origin, evolution, co-evolutionary patters, geographical dispersion, and even how to recognize it in the fossil record—are still problematic.
