Trilobite

Trilobites are a large group of marine arthropods that inhabited the oceans of the Palaeozoic Era in Earth’s history (520 – 250 million years ago). Trilobites first appeared in the Cambrian period approximately (520 million years ago) and with over 20,000 described species, they are one of the most popular fossils in any amateur or museum collection.

Trilobites come in a wide variety of shapes and sizes, but they all have a similar body plan, making it very easy to identify them. There are three main body parts, the cephalon (head), the segmented thorax (body) and the pygidium (tail). Trilobites are named, not for the body parts described above, but for their two lateral pleural lobes and the central axial lobes. These three lobes are found in all Trilobites and run from the cephalon to the pygidium. Additionally, trilobites occupied a wide variety of ecological roles in the Palaeozoic seas from bottom-dwellers on the sea floor eating smaller invertebrates or scavenging on larger organisms. Some were even predators and consumed plankton within the water column. These differences in lifestyle are reflected in their morphology, allowing palaeontologists to easily identify how the animal might have lived.

Trilobites have occupied our oceans for approximately 270 million years before they went extinct at the end of the Permian period (250 million years ago) in an extinction event known as the “Permo-Triassic” extinction event. This extinction is currently the most severe event to have occurred in Earth’s history, with approximately 95% of all life at that time died out. This catastrophic event is also known as the “Great Dying”.

Trilobites are extremely useful for relatively dating rocks because they are easy to identify, globally widespread, preserve extremely well and are limited to a geological time period. Using this information, we can determine the age of the rock by identifying the species of a trilobite. If you have a rock with a trilobite, or any fossil and would like to learn more, please send an enquiry through our client services.