Specimens of Eurypterus are the most common eurypterid fossils worldwide. They are particularly abundant in the Silurian Bertie Group of North America. The Bertie Group Eurypterus species are relatively small compared with associated giants such as Acutiramus, Eusarcana, and Dolichopterus. Here we report the discovery of an isolated telson of Eurypterus lacustris nearly 15 cm long indicating an individual more than half a meter in length. This highly maneuverable swimmer with acute vision joins the list of eurypterid predators with giant representatives.