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Ancient life · Life in the sea

Trilobites

Armoured sea arthropods that lasted for more than 250 million years.

Most 3 to 6 cm; giants such as Paradoxides up to 60 cm or more. Beside a person 1.75 m tall; ticks every metre.Body shape drawn for this site

When
Early Cambrian to the end of the Permian
Where
Seas worldwide; famous British finds include Dudley in the West Midlands
Size
Most 3 to 6 cm; giants such as Paradoxides up to 60 cm or more
A curled, ribbed trilobite fossil, the Dudley Bug, on a block of grey limestone.
Calymene blumenbachii, the Dudley Bug, in the collections of Amgueddfa Cymru, the National Museum Wales.Amgueddfa Cymru - Calymene blumenbachii - 214359 by Amgueddfa Cymru – Museum Wales, CC BY-SA 4.0, via Wikimedia Commons. Resized. This version is shared under CC BY-SA 4.0 too.

Trilobites appear abruptly early in the Cambrian and came to dominate the Cambrian and early Ordovician seas. After a long decline they finally died out at the end of the Permian, about 250 million years ago.

Most trilobites had compound eyes made of many separate lenses. Most were 3 to 6 cm long, but some, such as Paradoxides, were giants up to 60 cm or more, while the tiny blind agnostids were only a few millimetres long. Calymene blumenbachii from the Silurian rocks of Dudley was known locally as the Dudley Bug, and it is on the town’s coat of arms.

Trilobites640 Manow
Trilobites: 520 to 251.9 million years ago. That is 11% of the way back to the Earth’s birth.Periods from the ICS chart

Found in Britain. See where Britain was at the time in Britain’s journey.

Read more in The first animals.

Also in life in the sea

Sources