Leedsichthys was a type of fish that lived in the middle of the Jurassic period.
It may have been the largest fish to ever swim in the oceans of our planet
Earth. The exact length is not known; a complete skeleton has not been found.
But based on fossilized remains that have been discovered, it is estimated that
Leedsichthys must have been at least 15 m. (about 50 feet) long. Some people
think that Leedsichthys might have sometimes grown to a length of 30 m.
Leedsichthys was not a shark; it was a bony fish. Thus it differed from sharks,
which are cartilaginous fishes. This excerpt from an article by Jeff Liston
tells about a recent excavation of a fossilized Leedsichthys:

In July 2001, I received a bone in the mail which I identified as being part of
a dorsal fin of Leedsichthys. Visiting the site 3 months later, it was apparent
that there were over a dozen bones belonging to this fish emerging from the same
clay level of a cliff in a Peterborough brick pit. The bones protruded over a
length of more than 8.5 metres. This was extremely likely to be one individual
animal, possibly still articulated, spread over a bed of clay - an opportunity
for excavation that simply could not be missed, as the last substantial partial
skeleton of this fish was found in 1913. A 20 metre cliff was removed during the
last week of June the following year (2002), and diggers began to work with
dental tools, paring away the cliff from the fragile bone fragments that
saturated the now revealed bed of clay. The expected dig time of 2 weeks proved
to be ludicrously optimistic - the dig ran for a solid 10 weeks, and some more
work was done (primarily for the benefit of the
cameras, it has to be said) over a weekend in November. By the end of that
time, over 2,100 bones had been recovered (in the course of 3.119 staff hours),
and their positions thoroughly recorded on plastic mapping sheets - with one or
two exceptions: one extremely experienced digger, all too eager to perform for
the cameras, excavated and lifted ahuge skull bone, neglecting to map it first -
then could not remember where it had come from!
But aside from this exception, the diggers performed the all-too difficult task
of extracting the delicate bone fragments from the clay and numbering them
against recorded locations with aplomb, acquitting themselves well in a dig that
was uniquely difficult through the exceptional fragility and large size of the
fossil remains.
The fish gained the nickname 'Ariston' (because the quantity of bone simply went
on ... and on ...), and the resulting television programme (which does not
feature the rash removal of the skull bone!) was broadcast on Monday 8th
September, 2003 at 8:30 pm on Channel 4 as part of the RDF series 'The Big
Monster Dig'. Since that programme was made a team has returned to clear the bed
over two weeks in August this year (2003), and it is planned to excavate more of
the bed next summer. So far, the dig has yielded many paired bones (left and
right equivalents), something never before recorded for the fish, many bones
recorded in isolated specimens, and some completely new bone morphologies.

Liston goes on to mention that many organizations gave financial support to the
dig. They included:
NERC emergency funding
Aggregates Levy Sustainability Fund
Paleontological Association
East Midlands Geological Society
National Museums of Scotland
University of Portsmouth
Hunterian Museum

Neal Robbins

P.S. Fossilized remains of Leedsichthys were first found by a farmer named
Alfred Leeds, who was a fossil collector. He discovered the bones in the Oxford
Clay, a Jurassic mudrock. Leeds eventually sold the fossils to what is now the
Natural History Museum in London. Arthur Smith Woodward studied them. He named
and described Leedsichthys in 1889. Woodward first thought that Leedsichthys was
related to sturgeons. However, he ultimately realized that Leedsichthys was of
an extinct family called Pachycormidae.

P.P.S. Leedsichthys is of the class Actinopterygii and the subclass Neopterygii.
The order is Pachycormiformes.







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