Dunkleosteus is an extinct genus of arthrodire placoderm fish that existed during the Late Devonian period, about 360–380 million years ago. Some of the species, such as D. terrelli, D. marsaisi, and D. magnificus, are among the largest arthrodire placoderms ever to have lived. The largest species, D. terrelli, measuring up to 6 m (20 ft) long and 1 t (1.1 short tons) in weight, was a hypercarnivorous apex predator. Few other placoderms, save, perhaps, its contemporary Titanichthys, rivaled Dunkleosteus in size.