Hibbertopterus scouleri

Hibbertopterus is a genus of eurypterid, a group of extinct aquatic arthropods. Fossils of Hibbertopterus have been discovered in deposits ranging from the Devonian period in Belgium, Scotland and the United States to the Carboniferous period in Scotland, Ireland, the Czech Republic and South Africa. The type species, H. scouleri, was first named as a species of the significantly different Eurypterus by Samuel Hibbert in 1836. The generic name Hibbertopterus, coined more than a century later, combines his name and the Greek word πτερόν meaning "wing".

Like other known hibbertopterid eurypterids, Hibbertopterus was a large, broad-bodied and heavy animal. It was the largest known eurypterid of the suborder Stylonurina, composed of those eurypterids that lacked swimming paddles. A carapace referred to the species H. scouleri, from Carboniferous Scotland, measures 65 centimetres wide. Since Hibbertopterus was unusually wide relative to its length for a eurypterid, the animal in question would probably have measured around 180–200 ...

In 1831, Scottish naturalist John Scouler described the remains, consisting of a massive and unusual prosoma and several tergites, of a large and strange arthropod discovered in deposits in Scotland of Lower Carboniferous age, but did not assign a name to the fossils. Through Scouler's examination, the fossils represent the second eurypterid to be scientifically studied, just six years after the 1825 description of Eurypterus itself.

Cyrtoctenus and Dunsopterus Many analyses and overviews treat the ten species assigned to Hibbertopterus as composing three separate, but closely related, hibbertopterid genera

Hibbertopterids such as Hibbertopterus were sweep-feeders, having modified spines on their forward-facing prosomal appendages that allowed them to rake through the substrate of their living environments. Though sweep-feeding was used as a strategy by many genera within the Stylonurina, it was most developed within the hibbertopterids, which possessed blades on the second, third and fourth pair of appendages. Inhabiting freshwater swamps and rivers, the diet of Hibbertopterus and other sweep-feed.