Fossil of an Extinct Trilobite

Tan, U-shaped fossil on a black background. Fossil has three segments: Head, neck or thorax, and tail with about 12 legs.

Trilobites are extinct, but lived on Earth for about 290 million years, achieving incredible abundance during from the Cambrian to Devonian. Trilobites are one of the most diverse groups of extinct organisms known. Their variety of body forms were undoubtedly specialized to different modes of life. Imagine tiny (1 mm long) trilobites floating in the ocean and filter-feeding on suspended detritus, juxtaposed with a large (60 cm, or 2 feet long) predatory trilobite crawling on the seafloor and catching worms. The last trilobite lineages disappeared during the huge end-Permian extinction event (about 252 million years ago). Image 2007-7263 of Trilobites Crotalocephalus by Chip Clark, Smithsonian.