Like the order Phacopida, the proetids have exoskeletons that sometime have pits or small tubercles, especially on the glabella (middle portion of the head).

These two features can aid in distinguishing proetids from some phacopid trilobites in the suborder Phacopina, to which they can be very similar.

[2] Others observe that globular non-adult larvae also occur in some taxa within the proposed order Aulacopleurida.

More recently phylogenetic analysis of both larval and adult characters suggests the proetids as earlier understood probably are monophyletic.

The analysis identifies the taxa Asaphida, Olenina and Phacopida (including the Holotrachelidae) as sister groups.

The sixth node combines a restricted Bathyuridae split off from Bathyurella with the family Proetidae (including Phillipsiidae, which, according to Lamsdell, has been demoted to the subfamily Phillipsiinae).