Leedsichthys

Leedsichthys
Temporal range: Middle Jurassic
Leedsichthys with scuba-diver for scale
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Actinopterygii
Order:
†Pachycormiformes
Family:
†Pachycormidae
Genus:
†Leedsichthys

Woodward, 1889
Binomial name
Leedsichthys problematicus
Woodward, 1889

Leedsichthys problematicus ("leeds fish") was a giant fish of the Jurassic period. Its fossils were first found in England.

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 metres. The blue whale is twice as long, at 30 metres, but it is a mammal, not a fish.

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.

Leedsichthys fossils have also been found in France, Germany and Chile.

Size comparison of different pachycormiformes

Description

Remains

Many remains of this fish are very incomplete, despite over 70 being discovered, largely because many skeletal elements did not ossify. Furthermore, the fish's skeleton was mostly made out of cartilage, which rarely fossilises.

Size

Leedsichthys was the largest member of the Osteichthyes. Iincomplete fossils and the lack of a preserved vertebral column, however, has made it difficult to know its exact length. Old size estimates said the largest individuals would reach 27.6 metres (91 feet). Subsequent estimates also mentioned Leedsichthys would be around 30 metres.

In a paper published in 2013, Liston and colleagues revised the Leedsichthys's length using bone-ring analysis. Based on their research, the largest individuals would reach about 16.5 metres (54 ft) long.

Food

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.

References

  1. 1 2 3 4 5 6 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
  2. ↑ Martill, D.M. (1986). "The world's largest fish". Geology Today. March–April: 61–63.
  3. ↑ Martill, D.M. (1988). "Leedsichthys problematicus, a giant filter-feeding teleost from the Jurassic of England and France". Neues Jahrbuch für Geologie und Paläontologie.
  4. ↑ Catch the 100ft fish, The Mirror, London, England. September 18, 2003.
  5. ↑ Liston, Jeff; Newbrey, Michael; Challands, Tom; Adams, Colin (2013-06-01), Growth, age and size of the Jurassic pachycormid Leedsichthys problematicus (Osteichthyes: Actinopterygii), pp. 145–175, ISBN 978-3-89937-159-8, retrieved 2026-08-27

Other websites

Media related to Leedsichthys at Wikimedia Commons