The Nepeidae are a family of

trilobite Trilobites (; meaning "three-lobed entities") are extinction, extinct marine arthropods that form the class (biology), class Trilobita. One of the earliest groups of arthropods to appear in the fossil record, trilobites were among the most succ ...

s, that lived during the late Middle Cambrian - earliest Upper

Cambrian The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordov ...

in what are today Australia, Antarctica, China and New Zealand. The Nepeidae can be recognized by a vaulted area between the front of the glabella and the frontal border, eye ridges that extend outward and slightly forward from the front of the glabella, and fixed cheeks that cut into the free cheeks at the inside of the eye, and that extend backwards, forming the inner base of the genal spines. The genal spines, however, are part of the free cheeks and extend backward at least half the length of the thorax. The

thorax The thorax (: thoraces or thoraxes) or chest is a part of the anatomy of mammals and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main di ...

has at least 20 segments. The tail shield (or

pygidium The pygidium (: pygidia) 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 females, the ovipositor. It is compos ...

) is small.

References

Ptychoparioidea Trilobite families Cambrian trilobites Drumian Guzhangian Miaolingian first appearances Miaolingian extinctions {{Ptychopariida-stub