Liopleurodon harrassing Leedsichthys
Leedsichthys was a giant pachycormid (an extinct group of Mesozoic bony fish) that lived in the oceans of the Middle Jurassic period. The closest living relative of the pachycormids is the bowfin, Amia calva, but this is only very distantly related. The name Leedsichthys means "Leeds' fish", after the fossil collector Alfred Nicholson Leeds, who discovered it before 1886 near Peterborough, England. The fossils found by Leeds gave the fish the species epithet problematicus, because the remains were so fragmented that they were extremely hard to recognize and interpret.
The remains of Leedsichthys have been found in the Callovian of England, northern Germany and France, the Oxfordian of Chile, and the Kimmeridgian of France.