Name: Leedsichthys
(Leed's fish).
Phonetic: Leeds-ick-fiss.
Named By: Arthur Smith Woodward - 1889.
Classification: Chordata, Actinopterygii,
Pachycormiformes, Pachycormidae.
Species: L. problematicus (type).
Diet: Filter feeder.
Size: Estimates vary but the larger specimens may
have approached up to 16 meters long.
Known locations: England, France, Germany, Chile.
Time period: Oxfordian of the Jurassic.
Fossil representation: Many specimens of over 70
individuals are known.
The
secret to
the large size of Leedsichthys is probably down to
its lifestyle as a
filter feeder. This method of feeding requires very littler effort
other than opening the mouth and cruising near the surface of the
water. Such a method of feeding requires only a slow metabolism as it
is not actively hunting for prey. Its large size however may mean that
it was possibly gigantothermic like many of the large fish we know
today.
Because
of the fragmentary
nature of recovered remains, the exact size has been open to much
speculation. Most researchers agree that a size of nine to ten meters
long is realistic, but also recognise isolated remains that are larger
than they appear in more complete specimens. This in turn has pushed
the maximum estimate to a potential sixteen meters long. In contrast,
the largest living fish today is the whale shark with a maximum
recorded body length being just over twelve and a half meters. Some
estimates have further pushed the maximum size of Leedsichthys
to
beyond twenty metres.
Leedsichthys
has been named
after Alfred Nicholson Leeds who first discovered it in 1886. The type
species L. problematicus was so named because of
the difficulty
involved in recovering and reconstructing the first specimen.
1 - Basilosaurus (whale), 2 - C. megalodon - lower average estimate (shark), 3 - Livyatan melvillei - lower estimate (whale), 4 - Pliosaurus funkei, a.k.a Predator X (pliosaur), 5 - Plesiosuchus (thalattosuchian), 6 - Thalattoarchon (ichthyosaur), 7 - Dunkleosteus (arthrodire placoderm), 8 - Shastasaurus (ichthyosaur), 9 - Tylosaurus (mosasaur), 10 - Leedsichthys - upper estimate (fish)), 11 - Brygmophyseter (whale), 12 - Rhizodus (lobe finned fish). |
Further reading
- Preliminary notes on some new and little-known British Jurassic
fishes, Arthur Smith Woodward - 1889.
- The tail of the Jurassic fish Leedsichthys problematicus
(Osteichthyes: Actinopterygii) collected by Alfred Nicholson Leeds - an
example of the importance of historical records in palaeontology, J. J.
Liston & L. F. Noe - 2004.
- Homologies amongst the fragments: searching for synapomorphies in
shattered skulls. In: Poyato-Ariza FJ (ed) Fourth International Meeting
on Mesozoic Fishes - Systematics, Homology and Nomenclature, Extended
Abstracts, J. J. Liston - 2005.
- Lured by the Rings: Growth structures in Leedsichthys.
In:
Poyato-Ariza FJ (ed) Fourth International Meeting on Mesozoic Fishes -
Systematics, Homology and Nomenclature, Extended Abstracts., J. J.
Liston, L. Steel & T. J. Challands - 2005.
- The occurrence of the Middle Jurassic pachycormid fish Leedsichthys.
- Oryctos 9: 1-36. - J. J. Liston - 2010.