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NarrativeWikipediaarticle
Occurrence & distributionGBIF · PBDB11 006 records
Deep timePBDB984 fossils
01Narrative
Trilobites (; meaning "three lobes") are 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 () and they flourished throughout the lower Paleozoic before slipping into a long decline, when, during the Devonian, all trilobite orders except the Proetida died out. The last extant trilobites finally disappeared in the mass extinction at the end of the Permian about 252 million years ago. Trilobites were among the most successful of all early animals, existing in oceans for almost 270 million years, with over 20,000 species having been described. By the time trilobites first appeared in the fossil record, they were already highly diversified and geographically dispersed. Because trilobites had wide diversity and an easily fossilized exoskeleton, they left an extensive fossil record. The study of their 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. More recently they have been placed within the Artiopoda, which includes many organisms that are morphologically similar to trilobites, but are largely unmineralised. Trilobites evolved into many ecological niches; some moved over the seabed as predators, scavengers, or filter feeders, and some swam, feeding on plankton. Some even crawled onto land. Most lifestyles expected of modern marine arthropods are seen in trilobites, with the possible exception of parasitism (where scientific debate continues). Some trilobites (particularly the family Olenidae) are even thought to have evolved a symbiotic relationship with sulfur-eating bacteria from which they derived food. The largest trilobites were more than 45 cm long and may have weighed as much as 4.5 kg.
No narrative description available for this taxon yet.
How far back this lineage goes — and how we know. Everything here is measured in Ma, short for “mega-annum”: millions of years ago. The chart reads left to right like a calendar of the Earth, from the deep past on the left to today at the right edgetop to bottom like a core drilled through the Earth, from the deep past at the top down to today at the bottom.
At a glance
Fossil range539–27.3 Ma Cambrian → Paleogene
Dated fossil finds984
Most finds around455 Ma 186 finds · Ordovician
StatusNot recorded since 27.3 Ma
When this lineage existed
How to read this: the coloured strip along the bottomdown the left is the geological calendar — the standard periods (Jurassic, Cretaceous…) every museum uses, shown so you can see which chapter of Earth's history this lineage lived in. The dashed rules marked ✦ are the five great mass extinctions. The solid bar is the fossil range: the span between the oldest and the youngest fossil that palaeontologists have assigned to Trilobita. Above itBeside it, the bars count how many dated finds fall in each slice of time; the tallest bar is labelled, and heights use a square-root scale so that thin slices stay visible next to rich ones. Read this as how well each stretch of time is preserved and studied — thick bars mean plenty of the right kind of rock and plenty of collectors, which is related to, but not the same as, how common it actually was.
fossil range (PBDB)dated finds per slicemass extinction
The range bar reaches further than the finds. PBDB's range runs to 27.3 Ma, but the youngest dated fossil we can place on this axis is around 275 Ma. The young end of the bar rests on records that carry no usable date, so treat it as the weaker of the two claims.
How it livedPBDB
Environmentmarine
Life habitlow-level epifaunal
Dietcarnivore
Motilityfast-moving
Compositionlow Mg calcite, chitin
Ontogenymolting,addition of parts
08Occurrence & distribution
Record type11 006 records
Museum / vouchered878
Fossil10 128
Range
Area of Occupancy AOO1 900 km²
Museum / Voucheredphysical evidence
Backed by a physical specimen — a herbarium sheet, sample or voucher held in a collection. “Vouchered” means supported by material evidence, not just an observation.
Coordinate accuracy75% within 1 km
≤1 km 18≤10 km 6
24 georeferenced · 854 without coordinates
Open the institutions mapphysical evidence878
10Collections & institutions
Holding institutions3 of 3 geolocated
Institutions and collections holding physical, vouchered specimens of this species — click a row to fly to it on the map.
Institution
Specimens
Edmonton, CA
60
Vancouver, CA
19
Cambridge, US
3
3 institutions · 82 of 878 vouchered records shown
