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species of fish (fossil)

Leedsichthys problematicus ("leeds fish") was a giant fossil fish of the Jurassic period. It was a pachycormid, a group of extinct ray-finned fishes (Actinopterygii). Leedsichthys is the largest fish known, with an estimated length of up to 16 meters.[1] The blue whale is twice as long, at 30 metres, but that is a mammal, not a fish.

Temporal range: Middle Jurassic
Leedsichthys problematicus.jpg
Leedsichthys with scuba-diver for scale
Scientific classification
Binomial name
Leedsichthys problematicus

Leedsichthys fossils are incomplete, making it impossible to know the exact length. The fossil is named after its discoverer, Alfred Nicholson Leeds, who discovered it before 1886 near Peterborough, England.[1] No full fossil is known, mainly because parts of the skeleton were made of cartilage, which does not fossilise. The front of the snout was made of cartilage.


Like the world's biggest fish today, the whale shark, Leedsichthys was a filter feeder, getting its nutrition from plankton. Remains of over 70 individuals have been found.[1]


  1. 1.0 1.1 1.2 Liston J.J. 2004. An overview of the pachycormiform Leedsichthys. In: Arratia G and Tintori A (eds) Mesozoic Fishes 3 - Systematics, Paleoenvironments and Biodiversity. Pfeil, München. 379-390