Though early discoveries of Pterygotus were confined to England and North America, fossil finds throughout the 20th century would help establish that Pterygotus as a genus achieved a nearly cosmopolitan distribution.
The first eurypterid to be discovered in Australia was Pterygotus australis, whose fossils were found in the Ludlow age Melbourne Group of the Dargile Formation.
The fossils referred to P. australis, consisting of four fragments making up about half of a segment that were discovered during the process of excavations beneath Melbourne during the construction of new drainage works for the city in 1899.
The fragmentary fossils closely resemble fossils of Erettopterus bilobus (classified as a species of Pterygotus at the time), which might make their assignment to Pterygotus questionable.

Kjellesvig-Waering named the species P. bolivianus in 1964 based on fossils recovered from deposits of Emsian-Eifelian (Early to Middle Devonian) age in Bolivia.
This species was the first pterygotid to be discovered in South America, the first Devonian pterygotid to be recovered in deposits in the Southern Hemisphere and also represents one of the last known living member of the pterygotid family.
The specimen (PE6173, housed at the Chicago Natural History Museum) includes the well-preserved anterior half of a chelicera and ramus.
The tooth of the ramus are short, wide and conical, all being slightly curved backwards.
The terminal tooth is larger, but only slightly, than the tooth succeeding it and the inwards bend of the claw suggests that another tooth might be present, creating a kind of "double tooth combination" that is also present in some other species, such as P. lightbodyi, P. impacatus and Erettopterus brodiei.
The total length of the fossilized ramus is 2.35 cm (1 in), but it likely only represents around half of the full ramus.
As in other species (and the Pterygotidae in general), the teeth are finely ribbed.
It can be distinguished from all other species of Pterygotus by the wide but short and evenly sized teeth as well as the terminal tooth not having any particular development.
In 2019, a new fragmentary ramus of a chelicera was found in the Cuche Formation of Colombia.
The specimen (SGC-MGJRG.2018.I.5), assigned with uncertainty to P. bolivianus due to similarities with its holotype, represents the first eurypterid of Colombia and the fourth of South America.
The fossil was dated as Frasnian (Late Devonian), showing that Pterygotus did not become extinct during the Middle Devonian as previously thought.

Following close examination and the discovery of new fossil evidence, further genera would be split off from Pterygotus.
P. rhenaniae was classified as part of its own genus, Jaekelopterus, by Charles D. Waterston in 1964.
He considered the species sufficiently distinct from other Pterygotus species due to its supposedly segmented genital appendage (a feature later realized to be wrong), its narrow and long chelicerae, and its primary teeth being angled slightly anteriorly.
Another species, P. ventricosus, was classified as the separate genus Ciurcopterus in 2007 by O. Erik Tetlie and Derek E. G. Briggs, distinguished primarily by sharing several features with more basal pterygotioid eurypterids, such as its appendages being similar to those of Slimonia.
Though early discoveries of Pterygotus were confined to England and North America, fossil finds throughout the 20th century would help establish that Pterygotus as a genus achieved a nearly cosmopolitan distribution. The first eurypterid to be discovered in Australia was Pterygotus australis, whose fossils were found in the Ludlow age Melbourne Group of the Dargile Formation. The fossils referred to P. australis, consisting of four fragments making up about half of a segment that were discovered during the process of excavations beneath Melbourne during the construction of new drainage works for the city in 1899. The fragmentary fossils closely resemble fossils of Erettopterus bilobus (classified as a species of Pterygotus at the time), which might make their assignment to Pterygotus questionable.
Kjellesvig-Waering named the species P. bolivianus in 1964 based on fossils recovered from deposits of Emsian-Eifelian (Early to Middle Devonian) age in Bolivia. This species was the first pterygotid to be discovered in South America, the first Devonian pterygotid to be recovered in deposits in the Southern Hemisphere and also represents one of the last known living member of the pterygotid family. The specimen (PE6173, housed at the Chicago Natural History Museum) includes the well-preserved anterior half of a chelicera and ramus. The tooth of the ramus are short, wide and conical, all being slightly curved backwards. The terminal tooth is larger, but only slightly, than the tooth succeeding it and the inwards bend of the claw suggests that another tooth might be present, creating a kind of "double tooth combination" that is also present in some other species, such as P. lightbodyi, P. impacatus and Erettopterus brodiei. The total length of the fossilized ramus is 2.35 cm (1 in), but it likely only represents around half of the full ramus. As in other species (and the Pterygotidae in general), the teeth are finely ribbed. It can be distinguished from all other species of Pterygotus by the wide but short and evenly sized teeth as well as the terminal tooth not having any particular development. In 2019, a new fragmentary ramus of a chelicera was found in the Cuche Formation of Colombia. The specimen (SGC-MGJRG.2018.I.5), assigned with uncertainty to P. bolivianus due to similarities with its holotype, represents the first eurypterid of Colombia and the fourth of South America. The fossil was dated as Frasnian (Late Devonian), showing that Pterygotus did not become extinct during the Middle Devonian as previously thought.
Following close examination and the discovery of new fossil evidence, further genera would be split off from Pterygotus. P. rhenaniae was classified as part of its own genus, Jaekelopterus, by Charles D. Waterston in 1964. He considered the species sufficiently distinct from other Pterygotus species due to its supposedly segmented genital appendage (a feature later realized to be wrong), its narrow and long chelicerae, and its primary teeth being angled slightly anteriorly. Another species, P. ventricosus, was classified as the separate genus Ciurcopterus in 2007 by O. Erik Tetlie and Derek E. G. Briggs, distinguished primarily by sharing several features with more basal pterygotioid eurypterids, such as its appendages being similar to those of Slimonia.
Pterygotus