GEOLOGY

Detailed explanation-1: -Because they evolved rapidly, and moulted like other arthropods, trilobites serve as excellent index fossils, enabling geologists to date the age of the rocks in which they are found.

Detailed explanation-2: -For instance, Bathyuriscus rotundatus is a trilobite index fossil used to date rocks from the Middle Cambrian (505 million years ago).

Detailed explanation-3: -There are some types of index fossils which include Ammonites, Brachiopods, Graptolites, Nanofossils and Trilobites.

Detailed explanation-4: -Their fossilized remains are found in the rugged mountains of western Canada, the rolling plains of eastern Europe, the scorching deserts of northern Africa and the verdant hills of southern China. Indeed, trilobites can be discovered on every continent on earth where Paleozoic outcroppings exist.

Detailed explanation-5: -Cer-tain floral and faunal remains are often found to be restricted to a particular geologic horizon. Such fossils are known as ‘index fossils’ or ‘guide fossils’. Thus, index fossil is an abundant and easily identifiable fossil with a wide geographic distribution and a short geologic range.