Fossil trilobite

Fossil trilobite
Paradoxides carens

Trilobites were one of the first arthropods (invertebrates with exoskeletons and jointed limbs), appearing in the oceans of the Cambrian period about 521 million years ago. They were extremely common – over 17,000 species have been described, ranging in length from about 3 millimetres to 70 centimetres. The last of the trilobites died out in the Permian mass extinction about 250 million years ago.

The name ‘trilobite’ comes from the structure of the body. Three lobes can clearly be seen on the fossil – a central raised lobe with two flattened lobes on either side.

Trilobites are one of the most commonly found fossils. Not only were there numerous species, but their hard exoskeleton could be easily preserved in ocean bed sediment. Even their moults have been found as fossils.

Mid Cambrian, 515 million years ago, Czech Republic