Appendages: the jointed legs

All arthropods have articulated legs which are covered by a hard, rigid cuticle and are joined together by flexible membranes. The cuticle, which forms part of the exoskeleton, is made of mainly chitin. The membranes allow movements and locomotions.

There are 31 pairs of appendages in trilobites: one pair in antennae; three modified pairs in cephalic region; five pairs in pygidium and eight in abdominal tract as limbs.

The legs were rarely perserved in the fossil record. The X-ray photograph (left) is to used to show the arrangement and position of the legs and appendages.