The pygidium is the posterior body part or shield of crustaceans and some other arthropods, such as insects and the extinct trilobites. In groups other than insects, it contains the anus and, in femal

Thoracocare is a minute to very small trilobite, that lived during part of the Middle Cambrian in what are today the states of Idaho, Nevada and Utah. It is the only trilobite known with just two thor