T he trilobites
were one of the most successful groups of organisms to have ever lived.
The first trilobite appeared in the Lower Cambrian and became
extinct by the end of Permian. In their 350 million years of
existence, trilobites evolved into diverse forms adapting to
different marine environments. Trilobites are among the first to have
developed the highly sophisticated visual organs.
Trilobites are arthropods,
their bodies divided into segments; protected themselves by exoskeleton.
Compound eyes in trilobites are thought to be related to the
compound eyes of the modern arthropods. Modern day arthropods
include spiders, shrimps, lobster and other joint-legged organisms.
The most characteristic feature
is the three lobes found along the posterior-anterior axis. Its
name is also derived from this characteristic: tri-lob-ite (three
lobed things). The largest trilobites were measured up to more
than a meter long and the smallest reached a few millimeters.
On average, trilobites are two and seven centimetres long. Some
had spikes all over the body. Some lacked eyes or had elaborate
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