Pterygotus anglicus is a species of the Early Devonian euryptetids (sea scorpions) (order Eurypterida、family Pterygotidae) ⁴⁾, and has been found in Scottland and Canada ⁴⁾. Some lineages of eurypterids(order eurypterida) are 2 m or more in length, which are the largest arthropods to have ever found ^{2), 4)}.

Although eurypterids are called "sea scorpions" informally and are resemble the extant terresterial scorpions morphologically, they are not specifically the closest relatives ²⁾. Many questions related to the evolution and the phylogeny of eurypterids still remain.

The body length is approximately 1 m. The walking legs (appendages II - V) are slender, the appendage VI is a paddle-shaped swimming leg, and the podomere (coxa) at its base is a gnathobase which is a feeding organ for grinding food ⁴⁾.

The first appendage is a large chelicera, which can cut prey but is not adapted for crushing, suggesting that Pterygotus was a scavenger that pinched and ate detritus or small animals ⁴⁾.

The gill covers (the plate-like operculums) bearing the book gills in their inside cover the ventral surface where the air-breathing organ called "Kiemenplatten" is located, indicating that eurypterids were able to breathe on land ³⁾.

The depositional environments in which the specimens were found was a fluvial and these environments may have been partially connected to the marine, suggesting that Pterygotus was freshwater or brackish, such as lagoons or estuaries ⁴⁾.

The "mas-moult-mate" hypothesis, eurypterids have migrated and molted in a group, and they have adopted the reproductive method using spermatophore transfer on land like did the extant arachnid has been proposed ¹⁾. However, masticating food using gnathobase and the paddle-like swimming appendage indicate that their primary habitat was aquatic environment ³⁾. They have sometimes crawled to the land to take advantage of the shallow water and pools as quiet environments during reproduction and molting.