Pterygotioidea is a superfamily of eurypterids, an extinct group of aquatic arthropods. Pterygotioids were the most derived members of the infraorder Diploperculata and the sister group of the adeloph
Slimonia acuminata 1
Reconstruction of Hughmilleria socialis. Hughmilleria is a relatively basal pterygotioid.
Slimonia acuminata reconstruction
Eurypterids, often informally called sea scorpions, are a group of extinct marine arthropods that form the order Eurypterida. The earliest known eurypterids date to the Tremadocian stage of the Ordovi
Pterygotioidea
…Pterygotioidea (the name deriving from the type genus Pterygotus, meaning "winged one") is a superfamily of eurypterids, an extinct group of aquatic arthropods. Pterygotioids were the most derived members of the infraorder Diploperculata and the sister group of the…
Illustration of Hibbertopterus, a large stylonurine (lacking swimming paddles) eurypterid
The holotype of Palmichnium kosinkiorum, containing the largest eurypterid footprints known
The supposed "gill tracts" of eurypterids have been compared to the air-breathing pseudotracheae present in the posterior legs of modern isopods, such as Oniscus (pictured).