ABSTRACT
If human-like aliens were to visit our present globe, they would probably be amazed by arthropods and their diversity in constructions, shapes, colors and life styles. Without even considering the terrestrial forms, there are thousands of marine species of crustaceans alone from lobsters to ostracods, not to mention the extinct forms. The Cambrian Burgess-type Lagerstätten confront us with arthropods that are weird and disparate even by modern standards. It would be a hopeless task to deal with the tremendous diversity of arthropods in the context of this book. Yet, there is an excuse for the omissions: most of them have unmineralized chitinous skeletons that became preserved only under exceptional conditions, such as the anoxic muds of Burgess-type Lagerstätten. The best known of the early groups are the trilobites. This is because their carapaces are more common than other arthropods due to a partly calcified (calcitic) cuticle that did not require exceptional conditions to be preserved.
