Trilobites are early forms of arthropods, comprising three segments - the cephalon (or head), the thorax (or body) and the pygidium (or tail) (see diagram, right). Although complete fossils are sometimes found, more commonly only single segments survive, and the shape of these needs to be recognised; otherwise interesting specimens may be overlooked.
Each segment has a number of features which can be critical to identification. Formal descriptions refer to these using the technical terms that have been developed, and these need to be learned if the descriptions are to be understood and applied. The diagram below shows and names most of the features that may be relevant. Refer to this diagram when using the descriptions given on this website. |
Segments of a trilobite
|