Fossils of the single and type species, D. menneri, have been discovered in deposits of the Early Devonian period (Lochkovian epoch) in the Krasnoyarsk Krai, Siberia, Russia.

Its prosoma (head) was subquadrate (almost square) to parabolic (nearly U-shaped), with (bean-shaped) to subovate (nearly oval) eyes and surrounded by a marginal rim.

[1] Dvulikiaspis was originally described in 1959 as a species of the eurypterid genus Stylonurus, S. menneri, based on one single nearly complete specimen, PIN 1271/2 (housed at the Paleontological Institute of the Russian Academy of Sciences, Moscow).

It was found in deposits near the Imangda River at the southwest of the Taymyr Peninsula, near Norilsk, Krasnoyarsk Krai (Russia, then the Soviet Union).

The specific name menneri honors the Russian paleontologist and geologist Vladimir Vasilyevich Menner, who discovered the fossil in 1956.

[1] Novojilov reported the presence of paired tubercles in the center of the second and fourth to sixth tergites of S. menneri, and he compared this new species with the Scottish eurypterid Lamontopterus knoxae (then also part of Stylonurus).

[3] Based on these tubercles, Novojilov would later assign S. menneri to the eurypterid genus Tylopterella, with whom it shared this characteristic.

They also described the two specimens collected in 1974, determining that all known material of this genus was subject to taphonomic distortion (that is, defects product of the fossilization of the organism).

They also noted that features such as the almost straight segment boundaries were shared with another chasmataspidid, Loganamaraspis, although the latter probably did not have a paddle-like sixth appendage.

[4] D. menneri was originally recognized as a species of Stylonurus in 1959,[3] being moved to Tylopterella in 1962 due to the apparent presence of paired tubercles in the tergites.

[2] This was demonstrated in 2014, when it was redescribed as a new genus of chasmataspidid and removed from Eurypterida, noting its distinction with other diploaspidids and suggesting a relationship with Loganamaraspis.

[5] The cladogram below is based on a larger study (simplified to only show chasmataspidids) from 2015 carried out by the paleontologists Paul A. Selden, Lamsdell and Liu Qi, expanded to include the species Diploaspis praecursor, described in 2017.

[1] D. menneri has been found alongside specimens of the chasmataspidids Heteroaspis stoermeri and Skrytyaspis andersoni, as well as the possible prosomapod Borchgrevinkium taimyrensis and indeterminate species of eurypterids like Acutiramus.

The chasmataspidids remains were collected at between 307 m and 308 m. Here, D. menneri has been found with fossils of S. andersoni and the eurypterids Pterygotus and Parahughmilleria hefteri.