Prehistoric life
Palaeontologists have identified more than 20,000 different trilobites, an amazingly diverse group of animals. They all lived in the sea: some burrowed in the mud, some crawled on the surface of the seabed and others swam about in open water or inhabited reefs. Although some types of trilobites were blind, most had well developed eyes with very sophisticated lenses that had a great depth of field. Some species had eyes on stalks and these are believed to have buried themselves in the mud, with only their eyes sticking out like periscopes.
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The eyes have it
Detailed vision was an evolutionary trump card for mantis shrimps and trilobites.
Detailed vision was an evolutionary trump card for mantis shrimps and trilobites.
Earliest eyes
Life's first complex eyes helped trilobites lead an active life.
Life's first complex eyes helped trilobites lead an active life.
Trilobite types
Streamlined swimmers or bottom crawlers, trilobite types are thought to be varied.
Streamlined swimmers or bottom crawlers, trilobite types are thought to be varied.
Trilobite treasure
Wales is one of the best places in the world for a vast range of trilobite fossil shapes and sizes.
Wales is one of the best places in the world for a vast range of trilobite fossil shapes and sizes.
The following habitats are found across the Trilobites distribution range. Find out more about these environments, what it takes to live there and what else inhabits them.
Discover what these behaviours are and how different plants and animals use them.
Additional data source: Animal Diversity Web
Discover the other animals and plants that lived during the following geological time periods.
Permian mass extinctionLearn more about the other animals and plants that also form these fossils.
Trilobites have featured it our folklore - learn more our ancestors beliefs
before we understood fossilisation and evolution.
Trilobites (/ˈtraɪlɵbaɪt/, /ˈtrɪlɵbaɪt/; meaning "three lobes") are a well-known fossil group of extinct marine arthropods that form the class Trilobita. Trilobites form one of the earliest known groups of arthropods. The first appearance of trilobites in the fossil record defines the base of the Atdabanian stage of the Early Cambrian period (521 million years ago), and they flourished throughout the lower Paleozoic era before beginning a drawn-out decline to extinction when, during the Devonian, all trilobite orders except Proetida died out. Trilobites finally disappeared in the mass extinction at the end of the Permian about 250 million years ago. The trilobites were among the most successful of all early animals, roaming the oceans for over 270 million years.
When trilobites first appeared in the fossil record they were already highly diverse and geographically dispersed. Because trilobites had wide diversity and an easily fossilized exoskeleton an extensive fossil record was left behind, with some 17,000 known species spanning Paleozoic time. The study of these fossils has facilitated important contributions to biostratigraphy, paleontology, evolutionary biology and plate tectonics. Trilobites are often placed within the arthropod subphylum Schizoramia within the superclass Arachnomorpha (equivalent to the Arachnata), although several alternative taxonomies are found in the literature.
Trilobites had many life styles; some moved over the sea-bed as predators, scavengers or filter feeders and some swam, feeding on plankton. Most life styles expected of modern marine arthropods are seen in trilobites, with the possible exception of parasitism (where there are still scientific debates). Some trilobites (particularly the family Olenidae) are even thought to have evolved a symbiotic relationship with sulfur-eating bacteria from which they derived food.
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Cambrian period
Ordovician period
Silurian period
Devonian period
Carboniferous period
Permian period
