Encrinurus is in the Encrinuridae family, within the Phacopida order, and under the Trilobita class (a group of extinct marine artiopodan arthropods).
Encrinuridae Family: Phacopida Order: Trilobita Class: Trilobites ( /tralbat, tr-, -lo-/; meaning "three lobes") are a group of extinct marine artiopodan arthropods that form the class Trilobita. 
