Eurypterus

Eurypterus is an extinct genus of eurypterids, aquatic arthropods known from Silurian fossils. Its fossils are among the most familiar examples of sea scorpions.

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Eurypterid: An extinct group of aquatic and terrestrial chelicerate arthropods commonly called sea scorpions. Eurypterus is one genus within this broader fossil group.
Eurypterus remipes: A species of Eurypterus described from Silurian deposits in New York. It is the best-known species and a state fossil of New York.
Eurypterid swimming paddle: A flattened rear appendage in some eurypterids adapted for propulsion through water. Eurypterus used its paddle-shaped appendages for swimming.
Pterygotus: An extinct genus of large eurypterids with powerful grasping appendages and a broad, flattened telson. Its much larger species contrast with the generally smaller Eurypterus.
Chelicerata: An arthropod subphylum that includes arachnids, horseshoe crabs, and extinct groups such as eurypterids. Its body plan places Eurypterus among chelicerate arthropods.
Bertie Group: A Silurian rock unit in New York and Ontario known for exceptionally preserved fossils. Its deposits yielded many of the classic Eurypterus specimens.
Eurypterid prosoma: The fused front body region of a eurypterid, bearing the eyes and six pairs of appendages. This region carried the eyes and limbs that shaped feeding and movement.
Jaekelopterus: An extinct genus of giant eurypterids that includes some of the largest known arthropods. Its exceptional size underscores how modest Eurypterus was by eurypterid standards.
Arthropod exoskeleton: A rigid external covering that supports and protects an arthropod’s body and is periodically shed during growth. Its preserved outer armor reveals the segmented body and appendages.
Waukesha Biota: A diverse Silurian fossil assemblage from Wisconsin preserved in fine-grained sediment. It includes eurypterid fossils that broaden the genus’s fossil record.