Object of the Month

Katie, Assistant Curator. Lapworth Museum of Geology, talks about her choice of the Object of the Month
Video transcript here

Crotalocephalus sp. trilobite



Trilobites were marine arthropods which lived between 525-250 million years ago. Like all arthropods they had an exoskeleton which protected them from predators as well as protecting their soft body parts. The trilobite exoskeleton was comprised of three parts, the cephalon (head), a segmented body called the thorax and the pygidium or ‘tail’. Trilobites first appeared in the rock record in the earliest Cambrian, and were quite complex organisms, possessing an exoskeleton and one of the first groups to have a complex visual system. They rapidly became a diverse and wide spread group living in a wide range of environments from shallow to deep marine water.

This exceptionally preserved trilobite displays sharp pleural and pygidial spines. It was found in Anti Atlas in Morocco and is from the Lower Devonian period and therefore approximately 415-400 million years old. Crotalocephalus sp. was likely to have lived on the sea floor, the spines on its thorax would have helped it not sink into the soft sediment as well as offering protection from predators.

Trilobites were a successful and diverse group for over 275 million years, however, after the Devonian,trilobites were confined to just one order the Proetida, and later following the major end Permian mass extinction event, which was responsible for the loss of 95% of all marine life, trilobites became extinct.