Megalograptus is a genus of eurypterid, an extinct group of aquatic arthropods containing five species, all based on fossil material found in the United States: M. alveolatus, M. ohioensis (pictured), M. shideleri, M. welchi and M. williamsae. They were predators, with the largest and best-known species, M. ohioensis, growing to 78 centimeters (2 ft 7 in). The two most distinctive features of Megalograptus were its massive and spined forward-facing appendages, and its sharp spike-shaped telson (the last division of the body). Attached beneath the non-venomous telson were a pair of rounded blade-formed lobes which made it capable of grasping. Researchers have been able to infer the coloration that specimens might have possessed in life, believed to be brown and black, with M. ohioensis being darker than the others. Megalograptus lived in near-shore marine environments, where it used its large appendages to capture prey. The predator may have been cannibalistic at times, like many modern chelicerates. (Full article...)