Incomplete larger specimens from another locality, representing either older T. xiushanensis or possibly a second species of Terropterus, are estimated to have reached 100 centimeters (3.3 ft) in length.

[3] Terropterus can be distinguished from other mixopterid genera mainly by the unique arrangement and the relative length of the spines on its third pair of appendages.

Because the spine patterns of the appendage and the proportions of the joints in the limb are more or less the same as in Xiushan fossils, they were referred, tentatively, to ‘Terropterus sp.’.

Wang and colleagues noted that it was difficult to determine whether these fossils represent a different second species of Terropterus, or (since they were larger) an older individual of T. xiushanensis.

The discovery of Terropterus, the only mixopterid known from the southern continent of Gondwana, as well as the oldest representative of the family, not only expanded knowledge on the morphological variety within the Mixopteridae but also extended the known temporal and geographical range of the group.

[5] In particular, the discovery of Terropterus, and the possibility of finding more fossil material in the future, was noted by Wang and colleagues as indicating that the Mixopteridae may have had a more cosmopolitan (worldwide) distribution than previously assumed.

[5] Terropterus could confidently be placed in within the Mixopteridae due to its styliform (in this case scorpion-like) telson and the morphology of its fourth and fifth pair of appendages, which were of Hughmilleria-type, characteristic of the mixopterids.

[5] In the phylogenetic analysis by Wang and colleagues, Terropterus xiushanensis was recovered as the sister taxon of Lanarkopterus dolichoschelus, consistent with what was expected from its morphology.

[2] Other animals whose fossils have been preserved in the lower member (early Silurian portion) of the Xiushan Formation include the trilobite Luojiashania, the gastropods Coelozone and Hormotoma, the brachiopods Eospirifer, Leptostrophia, Nalivkinia and Nucleospira, as well as fragmentary remains of another eurypterid, of the Pterygotidae family.