It has been suggested that Paleomerus and the closely related Strabops could be synonymous with each other, since they differ only in the size of the telson (the posteriormost division of the body) and the position of the eyes.

[4] Like some other arthropod clades, the strabopids possessed segmented bodies and jointed appendages (limbs) covered in a cuticle composed of proteins and chitin.

The head of the strabopids was very short, the back was rounded and lacked trilobation (being divided in three lobes), the abdomen was composed by eleven segments and succeeded by a thick tail-like spine, the telson.

The designated type species, P. hamiltoni, is named after Count Hugo Hamilton, who sent both fossils to the Swedish Museum of Natural History, Stockholm.

This new poorly preserved fossil contains molds of the first eleven segments, with a total corporal length estimated at 6.4 cm (2.5 in, being slightly larger than the holotype).

Bergström tentatively removed Strabopidae (at that time containing Strabops and Neostrabops) and Paleomeridae (only Paleomerus) from the order Aglaspidida based on the fact that the head tagma was too short to accommodate the six pairs of appendages then assumed to be present in aglaspidids.

Ironically, Bergström speculated that the number of pairs of appendages present in the three genera could be fewer than seven, as well as including a possible antennal segment.

[8] A study published by Derek Ernest Gilmor Briggs et al. in 1979 has shown that the aglaspidid Aglaspis spinifer had between four and five pairs of appendages, but not six, weakening Bergström's argument.

Although the outline of the body and the proportions between the prosoma and opisthosoma suggest an assignment to Paleomerus, P. makowskii differs from P. hamiltoni in its great width and in the form of the eleventh segment and telson, as well as in the eyes, placed in elevations with vertical and straight lateral walls.

[7] A year later, the British paleontologists Jason Andrew Dunlop and Paul Antony Selden eliminated Strabopida from the suborder Aglaspidida and classified them as the sister taxa of the latter based on the lack of aglaspidid apomorphies (distinctive characteristics), such as the lack of genal spines (a spine placed in the posterolateral part of the prosoma).

[8] In 2004, the paleontologists O. Erik Tetlie and Rachel A. Moore described a fourth specimen of P. hamiltoni from the Mickwitzia Sandstone, PMO 201.957, housed at the Paleontologisk Museum, Oslo.

Finally, Tetlie and Moore conclude that the phylogenetic position of the strabopids will be difficult to determine without further material that preserves the ventral morphology.

[8] Subsequent authors have preferred to omit the strabopids from their analyses due to the poor abundance and preservation of their fossils, although the most accepted classification at the moment is of arthropods closely related to the Aglaspidida order, but not within it.

These are an abdomen divided into eleven segments followed by a thick spine (the telson), a short head with sessile compound eyes and a rounded back.

Størmer described Paleomerus as an intermediate form between Xiphosura and Eurypterida, only highlighting a unique feature different from Strabops, a twelfth segment.

[1] Nevertheless, a fourth specimen of the type species found in Sweden has shown that this extra segment actually represented the telson of the animal,[8] making them virtually indistinguishable.

[9] Aglaspida Strabops Paleomerus Neostrabops Triopus Duslia Pseudarthron Cheloniellon Lemoneites Weinbergina Bunodes Kasibelinurus Xiphosurida Diploaspis Chasmataspis Eurypterida Scorpiones Other arachnids Note that there are several outdated elements.

[1] In addition, P. makowskii has been associated in the Ociesęki Sandstone Formation with the trilobites Holmia kjerulf, Kjerulfia orcina, Schmidtiellus panowi and Ellipsocephalus sanctacrucensis, alongside various indeterminate species of gastropods, brachiopods and hyoliths.