Aglaspidida

Aglaspidida Temporal range: Cambrian –Ordovician PreЄ Є O S D C P T J K Pg N
Aglaspis spinifer
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
(unranked):	Arachnomorpha
Class:	†Artiopoda
Order:	†Aglaspidida Walcott, 1911

Aglaspidida is an extinct order of aquatic arthropods that were once regarded as primitive chelicerates. However, anatomical comparisons demonstrate that the aglaspidids cannot be accommodated within the chelicerates, and that they lie instead within the Artiopoda, thus placing them closer to the trilobites.
Aglaspidid fossils are found in North America (upper Mississippi valley, Missouri and Utah), Europe, Australia, and China.

Certain other artiopods are believed to be closely related to the aglaspidids, including the order Strabopida, which includes the genera Strabops, Khankaspis, Paleomerus, and Parapaleomerus.