Trilobites
Speaking of biodiversity, in this showcase you see fossils of the single most diverse class of extinct organisms, the Trilobites. They constitute an extinct class of jointed legged animals made up of over 20,000 described species. Still new species of trilobites are unearthed and described every year
What kind of skeleton do jointed legged animals have?
It is a box; organs and muscles are inside the box. The box has quite a lot of protrusions, called extremities, like legs, feelers. This exoskeleton is not able to grow. Before growing, the skeleton has to be shed. Then the animal grows quickly and after that, the new skeleton hardens. Many of the fossils of the trilobites are discarded shells.
All fossils in the showcase show only the upper side of the external skeleton, which is reasonably thick. The parts of the underside are invisible, including the limbs. Moreover, usually these parts are not even preserved. In many trilobites each of the bases of the limbs possess jagged tooth like structures. They are called gnathobases. Together they form a body length food processor. It cuts the food to pieces and transports the pieces forward to the mouth.
Remarkable are also the eyes. The majority of trilobites bore a pair of compound eyes (made up of many lensed units). Compound eyes in living arthropods such as insects are very sensitive to motion, and it is likely that they were similarly important in predator detection in trilobites. (Predator=animal preying on other animals, hunter)
Where doed the name Trilobite come from? The body has three lobes: left, middle and right.
Which lobes are to be seen on the foto?