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Longman Dictionary of Contemporary English
▪ As the trilobites spread through the seas of the world, they diversified into a great number of species.
▪ For example, you never find horse fossils among trilobite remains.&.
▪ The trilobites produced the mosaic eye which has been retained by the insects.
▪ The differences among the trilobites of different ages can be used by paleontologists to date these rocks.
▪ The external shell gives the crustaceans the problem it gave the trilobites.
▪ There are a number of Paradoxides species, which include some of the largest trilobites.
▪ This is one of the most primitive trilobites known.
▪ Trinucleid trilobites are blind, and with a greatly inflated mid-part of the head region.
The Collaborative International Dictionary

Trilobite \Tri"lo*bite\ (tr[imac]"l[-o]*b[imac]t), n. [Cf. F. trilobite. See Trilobate.] (Paleon.) Any one of numerous species of extinct arthropods belonging to the order Trilobita. Trilobites were very common in the Silurian and Devonian periods, but became extinct at the close of the Paleozoic. So named from the three lobes usually seen on each segment.

Douglas Harper's Etymology Dictionary

extinct marine arthropod, 1820, from Modern Latin Trilobites (Walch, 1771), from Greek tri- "three" (see three) + lobos "lobe" (see lobe); so called because its body is divided into three lobes.


n. (context biology English) An extinct arthropod of the class Trilobita, whose body had three large lobes.


n. an extinct arthropod that was abundant in Palaeozoic times; had an exoskeleton divided into three parts


Trilobites (; meaning "three lobes") are a 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 , and they flourished throughout the lower Paleozoic era before beginning a drawn-out decline to extinction when, during the Devonian, all trilobite orders except the Proetids died out. Trilobites finally disappeared in the mass extinction at the end of the Permian about . The trilobites were among the most successful of all early animals, roaming the oceans for over 270 million years.

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, 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 lifestyles; some moved over the sea bed as predators, scavengers, or filter feeders, and some swam, feeding on plankton. Most lifestyles expected of modern marine arthropods are seen in trilobites, with the possible exception of parasitism (where scientific debates still exist). Some trilobites (particularly the family Olenidae) are even thought to have evolved a symbiotic relationship with sulfur-eating bacteria from which they derived food.

Trilobite (disambiguation)

A trilobite is a member of a class of extinct marine arthropods.

Trilobite or Trilobites may also refer to:

  • Trilobites (genus), an obsolete genus of the marine arthropods
  • Electrolux Trilobite, a robot vacuum cleaner
  • Trilobyte (company), a computer game developer
  • The Trilobites, Australian rock band
  • Trilobite: Eyewitness to Evolution, a 2001 book by Richard Fortey

Usage examples of "trilobite".

By now the time-levels of the geological strata have been reliably mapped, and we can see that the period of trilobite dominance lasted an immensely long time -- so long that we are not really able to comprehend it.

But it was in the trilobite tribe that the concept was refined to a remarkable degree.

And he goes on to show us how the fossil evidence, hundreds of millions of years old, of these strange trilobite eyes that were stony even before they fossilized, gives us clues into the workings of their nervous systems and even into their varying ways of life in the oceans of remotest antiquity.

That one chapter on trilobite eyes is a work of magic, of fantasy, even -- and yet it is science in its purest form.

Tom and I have the north bedroom, which could really be called two rooms because of the little L-shaped anteroom off the end where Tom keeps his precious trilobite collection in a locked glass case.

Tom, like his father before him, has a family practice in Orangetown, a quick ten minutes away, but he spends at least a third of his time working on trilobite research, his hobby, his avocation, he would tell you in a kind of winking way so that you understand trilobites are his real work.

I went into Toronto with Tom to a one-day trilobite conference at the museum, and even attended a session, thinking it might provide distraction.

A paleontologist, a woman called Margaret Henriksen, from Minneapolis, lectured in a darkened room, and illustrated her talk with a digital representation of a trilobite folding itself into a little ball.

No one has ever seen a trilobite, since they exist only in the fossil record, but the sections of its bony thorax recorded in stone were so perfectly made that, when threatened, these creatures were able to curl up, each segment nesting into the next and protecting the soft animal underbodies.

After the conference in Toronto, some trilobite friends from England wanted to go for a meal at a place called the Frontier Bar on Bloor Street West, where the theme is Wild West.

Tom is writing a paper for the trilobite conference next year in Estonia.

No one knows a thing about the trilobite brain or even how they reproduced sexually.

Barrett stared up at the salmon moon and reached into his pocket to finger the little trilobite before he remembered that he had given it to Hahn.

The trilobite I crawled up on the shore no sand, no beach, just a shelf I of rock and advanced until it was eight or ten feet from the waves.

The trilobite completed its slow perambulation of the shoreline rocks and scuttered back into the sea unharmed.