Redlichiida
Introduction
Trilobites represent a group of sea-living animals that have been
extinct for over 250 million years. They are known mainly from their
exoskeletons, or shells, that provided a hard protective layer to which
soft body tissues and legs were attached during life. The body plan of
the trilobite exoskeleton is relatively complex. The name
‘trilobite’ comes from a division of the exoskeleton
width-ways into three lobes, 'tri-lobe-ite'. The division
is seen as a raised axial region running down the whole length of the
trilobite much like a spine, and two flat regions each side called the
pleural fields. Another division of three occurs lengthways with a
definite head end (the cephalon), middle region (the thorax), and tail
(the pygidium).
Everything we know about trilobites comes from fossils, and only
relatively recently have they been found with details of segmented legs
and antennae. This tells palaeontologists that trilobites are closely
related to modern insects, crustaceans and arachnids (spiders and
scorpions) grouped together as the arthropods.
There are nine groups of trilobites: the Agnostida, Redlichida,
Ptychoparida, Corynexochida, Lichida, Asaphida, Harpetida, Phacopida, Proetida. This website concentrates on the redlichids.
Paradoxidid trilobites could grow to a large size.
(Suborder Redlichina; Superfamily Redlicoidea)
Author: Sue Beardmore
Last updated: 18/11/06
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produced by students
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Palaeobiology programme in the Department
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