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. The blue whale is twice as long, at 30 metres, but that is a mammal, not a fish.
Temporal range: Middle Jurassic
|Leedsichthys with scuba-diver for scale|
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. 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.
- 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