Common name for a class of extinct ocean arthropods that lived during the Paleozoic Era, about 540 million to 245 million years ago
n any of numerous extinct marine arthropods of the class Trilobita of the Paleozoic era, having a segmented exoskeleton divided by grooves or furrows into three longitudinal lobes
Any one of numerous species of extinct arthropods belonging to the order Trilobita
Any of a group of ovate arthropods (subphylum Trilobita) that came to dominate the seas 540 million years ago and became extinct 245 million years ago. Trilobites had a chitinous exoskeleton and three body lobes: a raised middle lobe with a lower lobe on each side. The head, thorax, and tail were segmented; each segment bore two appendages. The forwardmost appendages were sense and feeding organs. Most species had two compound eyes, though some were eyeless. Some were predators, others were scavengers, and still others probably ate plankton. Paradoxides harlani, found near Boston, grew to 18 in. (45 cm) long and may have weighed 10 lbs (4.5 kg). Other species were small
an extinct arthropod that was abundant in Palaeozoic times; had an exoskeleton divided into three parts
Trilobites were very common in the Silurian and Devonian periods, but became extinct at the close of the Paleozoic
- extinct mobile marine with a body divided by two furrows into three parts; crayfish-like, related to millipedes, scorpions, sea spiders; important early fossil