UKS2 Topic: Dinosaurs & Fossils Block E: Ice Age Fossils Session 2
Fascinating Fossils
The story of the ammonite, the Megalosaurus and the
ichthyosaur
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Ammonites
Now we know that
ammonites were a sea
creature related to
squid that lived 220-65
million years ago.
When they were first
found, they were
thought to be magical
petrified curled snakes.
William Smith
William Smith was a
farmer's son but he
became a surveyor
working out where
canals could be built.
He got to see rocks and
fossils being dug up and
noticed that there were
several different types
of ammonite.
Strata
He noticed that each
type of ammonite was
always found in only
one type of rock.
He realised that the
ammonites changed
over time and the rocks
were from different
periods, all laid on top
of each other. He called
them strata.
Map of Britain
William realised that
these strata had folded
and eroded over time,
so sometimes older
rocks were at the
surface.
He made a map of
England, Wales and
some of Scotland
showing the different
layers, and ages, of rock
at the surface.
Why are ammonites important?
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They changed over time, so helped people move
towards the theory of evolution.
They were found with different rocks so helped
people to work out which layers of rock were older
or younger.
There are many of them in many different layers of
rock so they show that the earth is very, very old.
Megalosaurus
Now we know that there were lots of different types
of dinosaurs that lived 220-65 million years ago and
that Megalosaurus lived about 166 million years ago.
Great lizard
Fossil Megalosaurus
bones were found in
Stonesfield Quarry in
Oxfordshire.
William Buckland got
hold of them, and the
French scientist
Georges Cuvier visited
him and thought they
were from a giant
lizard.
Mary's contribution
Mary Morland, later Buckland's wife, made detailed
drawings of the giant lizard bones, like this one of a
jaw and teeth, that he could use in an article.
Dinosaurs
Buckland did more
work and announced
Megalosaurus to the
world in 1824.
After similar ‘giant
lizard’ bones were
found, Richard Owen,
who worked at the
British Museum,
invented the word
‘dinosaur’ to describe
them.
Why is Megalosaurus important?
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It was the first described dinosaur.
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It helped people realise that there was a whole
period of time when animals were very different:
the ‘Age of Lizards’.
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It started the study of dinosaurs as a group of
animals.
Ichthyosaur
Ichthyosaurs are not dinosaurs because they
lived in the sea.
They lived 248-85 million years ago.
Mary Anning
They were first found
and identified by Mary
Anning, a fossil
collector and seller
from Dorset.
Buckland often bought
fossils from her.
Unfairly, because she
was a woman she was
not given credit for her
finds.
Bezoar stones
Mary Anning found
strange stones in the gut
of the ichthyosaur. She
called them bezoar
stones.
William and Mary
Buckland did
experiments to work out
that bezoar stones were
actually fossilised
ichthyosaur poo!
Why are ichthyosaurs important?
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They showed that there weren't just very different
land animals in the past (dinosaurs) but also very
different animals in the sea.
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They were found by a woman.
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Their fossilised poo (coprolite) was the first to be
recognised. Now coprolite is very useful to work out
what ancient, extinct animals were eating.