trilobite

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trilobite

(trī`ləbīt'), subphylum of the phylum ArthropodaArthropoda
[Gr.,=jointed feet], largest and most diverse animal phylum. The arthropods include crustaceans, insects, centipedes, millipedes, spiders, scorpions, and the extinct trilobites.
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 that includes a large group of extinct marine animals that were abundant in the Paleozoic era. They represent more than half of the known fossils from the Cambrian period. The trilobite body was generally oval and flat and was divided into three roughly equal sections: the head, thorax, and tail. The name trilobite refers to a pair of furrows along the length of the animal that divided the body into three longitudinal regions. The body was covered by a mineralized shell. Because the dorsal, or upper, shell was thicker than the under shell, it has been the part best preserved in fossil form. Trilobites were abundant inhabitants of the Cambrian and Ordovician geological periods. They declined thereafter, possibly because they became food for cephalopods and later for fish, and became extinct in the Permian period. Trilobites are most closely related to the chelicerates, which include the horseshoe crabs and spiders.

Bibliography

See R. Fortey, Trilobite! Eyewitness to Evolution (2000).

trilobite

any extinct marine arthropod of the group Trilobita, abundant in Palaeozoic times, having a segmented exoskeleton divided into three parts
References in periodicals archive ?
Trilobite remains form excellent attachment surfaces for encrusting organisms.
2005) and Triassic (shone 1979), where the authors suggested it could have been made by arthropods in non-marine settings, given that trilobites do not extend into non-marine environments or beyond the Permian period.
Trilobites were arthropods, relatives of today's spiders and crabs.
Frederickson (1958) incluye la fauna de trilobites olenidos de Suramerica en la llamada provincia Atlantica o AcadoBaltica (Dinamarca, Noruega, Suecia, Gran Bretana, Terranova, Nueva Escocia, Mexico, Norte de Africa y China).
The Steppey Lane site is famous for its fossils of trilobites, some of the first animals on the planet.
The aim of this study was to investigate the distribution of the trilobites of the lowest part of the Ordovician limestone succession in the East Baltic and to observe their zonation in comparison with Scandinavian trilobite biozones.
Early Silurian Trilobites of Anticosti Island, Quebec, Canada
I'm interested in all aspects of life, and my expertise is in fossils called trilobites.
From the Allosaurus, Velociraptor, Meglasaurus, and Iguanodon, to Trilobites, Saber-Toothed Cats, Mammoths and Mastodons, "Exploring Dinosaurs & Prehistoric Creatures will prove an enduringly popular library acquisition and would make an ideal Memorial Fund selection.
It also made some exciting fossil finds, including a collection of trilobites in black shale.