Explain how trilobites meet each of the 4 criteria for being an index fossil.

Index fossils delineate the epochs of geologic time. In order for an organism to be considered as an index fossil it must possess at least one of the four characteristics: it must be unique, extensive, abundant and inadequate in geologic time. Most type of organism may be considered distinctive but not widespread which tolerate them to inhabit all over the world. While some are considered abundant that they were able to be developed as the most susceptible to environmental modification and destruction. Just like the trilobites, this is known as a precise example of index fossil for the Paleozoic rocks that is inhabit in all parts of the ocean. They develop new species throughout their being, which is according to some reports, lasted 270 million years from Middle Cambrian time to the termination of the Permian Period. Because of their ability to travel, they tend to dwell in global areas. The trilobites are huge that they can be used in a study even without a microscope and they are also hard-shelled invertebrates which make them petrified effortlessly.