Mycteroptids and hibbertopterids continued to survive for some time, with one genus of each group known from Permian strata: "Hastimima" and "Campylocephalus" respectively. "Hastimima" went extinct during the Early Permian, as "Adelophthalmus" had, while "Campylocephalus" persisted longer. A massive incomplete carapace from Late Permian (Changhsingian stage) deposits in Russia represents the sole fossil remains of the species "C. permianus", which might have reached in length. This giant was the last known surviving eurypterid. No eurypterids are known from fossil beds higher than the Permian. This indicates that the last eurypterids died either in the catastrophic extinction event at its end or at some point shortly before it. This extinction event, the Permian–Triassic extinction event, is the most devastating mass extinction recorded, and rendered many other successful Paleozoic groups, such as the trilobites, extinct.