FOCUS Book
When real scientists make a new discovery, they may
conduct a scientific argument with peers to discuss
what they found. Suppose you discovered a fossilized
skeleton of an unknown creature from the Jurassic
Period. Imagine the features of this skeleton, including
the type of teeth, the size and shape of the skull, and
the size and shape of the limbs. Draw a detailed sketch
of this skeleton and trade sketches with a classmate.
Looking at your classmate’s skeleton drawing, try to
determine what the animal was like when it was alive.
Was it a plant eater or meat eater? How can you tell?
Did it walk, swim, or fly? Why do you think so? Describe
in writing your classmate’s animal on the basis of
inferences you made about the skeleton. Then discuss
your findings with your classmate and see if you agree
about each other’s discovery.
Beyond the Book
Visit a natural history museum, or a museum
website, to view fossils and lifelike models
of creatures from the Jurassic Period.
T he Jurassic Period
FOCUS Question
How do extinct food chains compare
to food chains of today?
Patterns
Photo Credits:
Front cover: © Paul D. Stewart/Science Source; icons (used throughout): © Jupiterimages Corporation; pages
3 (top), 6 (bottom), 8 (bottom): © De Agostini Picture Library/Bridgeman Images; page 3 (bottom): © Richard
Bizley/Science Source; page 4 (left): © Ken Lucas/Visuals Unlimited/Corbis; page 4 (right): © Scott Camazine/
Alamy; pages 5 (left), 6 (top): © Roger Harris/Science Source; page 5 (right): © trevkitt/iStock/Thinkstock;
page 6 (center): © gsagi/iStock/Thinkstock; page 7 (main): © Jaime Chirinos/Science Source; page 7 (inset):
© Ihar Byshniou/iStock/Thinkstock; page 8 (top): © Tobias Bernhard/Corbis; page 9 (left): © USO/iStock/
Thinkstock; page 9 (right): © DeAgostini/DeAgostini/Superstock
Earth was very different
during the Jurassic Period.
But just like today, the
plants and animals that
lived during that time
belonged to food chains.
Living things were either
producers or consumers,
and each represented a link
in a now-extinct food chain.
Illustration Credit:
Page 2: Signe Nordin/© Learning A–Z
Jurassic Food Chains
© Learning A–Z
Written by Charles Piddock
All rights reserved.
www.sciencea-z.com
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AE
A
PANGAEA BECOMES THE
MODERN CONTINENTS
G
Equator
PA
N
Imagine if you could open a
door and suddenly step into
the time of dinosaurs. You
would find a very different
world. The Jurassic Period
was a time in Earth’s history
that lasted from about 200
to 145 million years ago.
The air was hot and moist,
similar to the air in today’s
Amazon rainforest.
Pangaea—a single, huge
continent—was breaking
apart into the continents
we know today.
Permian Period
(250 million years ago)
Laurasia
Equator
Gondwana
Tethys
Sea
Jurassic Period
(145 million years ago)
North
America
Europe Asia
South
America
Africa Equator
Antarctica
Present
During the Jurassic Period, the
landmasses that became today’s
continents were much closer
together and were separated
by warm, shallow seas.
Jurassic Life
Links in the C hain
During the Jurassic Period, moist
air, fertile soil, and strong sunlight
produced thick jungles that
covered vast areas of Earth.
Plants called cycads (SY-kadz)
Herbivores consumed
were especially common. Lush
the lush plant life of the
plant life (producers) supported
Jurassic Period.
large plant-eating dinosaurs. Insects were abundant.
They provided food for mouselike creatures that lived in
dense forests. In the late Jurassic Period, the feathered
dinosaur, Archaeopteryx, took to the skies. It was a
consumer that ate lizards, frogs, and beetles.
The structure of food chains during the Jurassic Period
was similar to modern-day food chains. Each living thing
had a niche (can rhyme with hitch or leash)—a specific
role within the environment. Some were producers that
provided energy to primary consumers. Small primary
consumers ate plants low to the ground. Taller herbivores
ate leaves high in the treetops.
Secondary consumers were predators; they ate primary
consumers. The top predators ate many types of
consumers, so they influenced many food chains.
Let’s learn about a few Jurassic animals and the niche
that each one occupied in its own food chain.
Jurassic oceans were warm and teeming with life.
Microscopic plankton provided food for fish and many
other sea creatures. Coral reefs grew in the warm
waters, and snails, mollusks, and fish flourished. Top
predators, such as paddle-finned plesiosaurs and giant
marine crocodiles,
ruled the sea.
Jurassic seas
supported many
different species
of organisms.
Food Chains • Jurassic Food Chains
Scientists are able to infer what dinosaurs ate by
examining fossil skulls and teeth. Plant eaters had short,
flat teeth designed for grinding up leaves and other
vegetable matter. Meat eaters had strong, sharp
teeth suited for tearing flesh.
herbivore
Artist’s rendering
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carnivore
Primary C onsumers
Stegosaurus (STEG-uh-SORE-us) was a large dinosaur
that weighed about 4,500 kilograms (10,000 lb.). It was
an herbivore that fed on plants close to the ground.
Because it had a short neck, it most likely ate mosses,
ferns, and low-growing cycads. Along its back, this
dinosaur had a double row of plates; no one knows the
purpose. Perhaps they protected the animal from meateating secondary consumers.
Some of the largest animals to ever live were sauropod
(SORE-uh-pod) dinosaurs of the Jurassic Period. One such
dinosaur was Brachiosaurus (BRACK-ee-uh-SORE-us). This
massive creature stood up to 16 meters (52 ft.) tall and
was 26 meters (85 ft.) long. An adult could weigh more
than 75,000 kilograms (165,000 lb.). For comparison, the
largest elephant weighs “only” 7,000 kg (15,000 lb.).
Brachiosaurus had a long neck that allowed it to eat
vegetation from the tops of lush trees such as tree ferns
and cycads. Despite its enormous size, this dinosaur most
likely traveled in herds for protection from predators.
Stegosaurus
Artist’s rendering
white-tailed deer
Artist’s rendering
sauropods
Dinosaurs were the dominant land
animals during the Jurassic Period.
But hiding among the leaf litter on
the forest floor were small, furry
Morganucodon
mammals that ate insects.
giraffe
Modern giraffes fill a similar niche in food chains to Brachiosaurus
during the Jurassic Period, eating vegetation from the tops of trees.
Food Chains • Jurassic Food Chains
Modern deer fill a similar niche
to Stegosaurus in the Jurassic
Period, eating from low-growing
trees and shrubs.
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Secondar y C onsumers
Metriorhynchus (MEH-tree-oh-RINK-us) was a Jurassic sea
creature shaped much like a large crocodile. Fossils show
that this dinosaur was about 3 meters (10 ft.) long. It was
completely adapted to a marine environment. It had large
paddle-like fins and a smooth, streamlined body.
Ceratosaurus (suh-RAT-uh-SORE-us) was a powerful
medium-sized carnivorous dinosaur. It was about
6 meters (20 ft.) long and weighed up to 950 kilograms
(2,100 lb.).
This carnivorous dinosaur
fed on a wide variety of
animals, including fish and
other sea life. While fearsome,
Metriorhynchus was not a
top predator. It was preyed
upon by an animal even higher
on the food chain.
This predator walked on two strong legs. It used its huge
hind claws and smaller front claws as killing weapons.
It had long, sharp teeth to grab and tear meat. It ate
other dinosaurs and may have also hunted in the water
to catch fish. Fossil tracks show that Ceratosaurus might
have hunted in packs. This kind of cooperative hunting
allows animals to capture more or larger prey than when
hunting alone.
Artist’s rendering
saltwater
crocodile
Ceratosaurus
Wolves occupy a similar niche
to Ceratoasaurus during the
Jurassic Period, hunting in
packs to bring down prey.
Food Chains • Jurassic Food Chains
Metriorhynchus
Artist’s rendering
Modern-day crocodiles occupy a similar niche to Metriorhynchus in
the Jurassic Period, hunting for aquatic animals.
wolves
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Artist’s rendering
Write your answers on separate paper. Use details from
the text as evidence.
1 Using details from the text, list two ways in which
Earth was different during the Jurassic Period than
it is today.
2 What is a niche, and how does it relate to food chains?
great white shark
Great white sharks occupy a
similar niche to Liopleurodon
during the Jurassic Period.
They are both apex predators
in their food chains.
3 Sauropods were the largest animals ever to walk
on Earth. Using what you learned about Earth
during the Jurassic Period, why do you suppose
they became so large?
Liopleurodon
4 Fossil evidence shows that Ceratosaurus hunted
in packs. What advantage did hunting in groups
give them?
Ter tiar y C onsumer
Liopleurodon (LEE-oh-PLUR-uh-don) was the Jurassic’s
top ocean predator. It ranged in length from 5 to 7 meters
(16–23 ft.). It was considered an apex predator because
no other animals preyed upon it. Leopleurodon used its
strong fins to zoom through the water, chasing down
Metriorhynchus, sharks, and anything else in its path.
Fossil skulls of Liopleurodon show that it had extremely
strong jaw muscles to clamp down on prey.
5 Using examples from the book, describe a typical
Jurassic food chain.
FOCUS Question
How do extinct food chains compare to food
chains of today? Describe at least two ways that
food chains of the Jurassic Period were similar
to food chains today. Then describe
at least two ways they were different.
Many different food chains existed during the Jurassic
Period. While the animals have changed, the important
links in food chains have remained similar across the ages.
Food Chains • Jurassic Food Chains
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