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Why did dinosaurs become extinct?
Why did dinosaurs become extinct? WHY DID DINOSAURS BECOME EXTINCT?
Dinosaurs have been fascinating people for many years. Why and how did such powerful reptiles become extinct so suddenly? It is a puzzle that has mystified scientists for a long time. Help us to study the evidence and solve the puzzle!
An information book collins.co.uk/collinsbigcat
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Claire Llewellyn 29/10/2021 15:05
Why did dinosaurs become extinct? Contents 1 Planet dinosaur
2
2 Age of the Dinosaurs
8
3 What caused the extinction of the dinosaurs? 12 4 A prehistoric puzzle
14
5 Extinction ideas
16
6 Weighing up the evidence
20
7 A new discovery
22
8 The last straw?
34
9 Not just the dinosaurs
36
10 Life returns
38
11 Did all the dinosaurs die?
40
12 The questions continue
42
Glossary
44
Index
45
Dinosaur extinction timeline
46
Written by Claire Llewellyn
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1 Planet dinosaur Long ago, in the ancient past, huge reptiles called dinosaurs lived on Earth. They lived on our planet for over 180 million years. There were hundreds of different kinds of dinosaur. They looked different from one another and they lived in different ways. Some dinosaurs lived in forests; others stayed near water. Some dinosaurs lived alone; others in packs. Some dinosaurs ate plants; others hunted for meat. Diplodocus was a long-necked giant that plodded along on four legs.
Compsognathus was a fastmoving, turkey-sized dinosaur. 2
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Then, quite suddenly, about 66 million years ago, dinosaurs became extinct. They simply disappeared. What might have happened to them? Why did they disappear?
Did you know? So far, about 700 different kinds dinosaur h have ki d off di been identified.
Allosaurus was a two-legged, powerful hunter.
3
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How do we learn about dinosaurs? It’s not easy to find out about animals that lived so long ago. Scientists can’t go back in a time machine to see what was happening then. Everything they know about dinosaurs comes from fossils. These are the traces of ancient animals found in rocks.
How a fossil sil forms After a dinosaur dies, the soft parts of its body rot away.
Its bones are covered by a thick layer of mud.
4
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Over millions of years, heavy layers of mud and sand build up on top. They harden into rock. Water seeps into the bones and, slowly, they change into stone.
Over time, the rocks are worn away by water, wind and ice. Parts of the fossil can now be seen, and sometimes someone finds it.
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What can fossils tell us? A dinosaur fossil provides scientists with evidence about life in the distant past. They study every fossil carefully. They want to know when the dinosaur was alive. Can you think how they might do this? Using special instruments, scientists test the rock where the fossil was found. This helps them to discover its age. If the rock is 150 million years old, then any fossil found in that rock is the same age.
This fossilised footprint was made 220 million years ago.
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Fossils often reveal the size of an animal and how it moved or ate. By comparing fossils from different times, experts can see how species slowly changed g to suit their surroundings. The fossilised jaw of the meat-eating Allosaurus. Unlike plant-eaters, it had long, sharp teeth.
Did you kknow? Scientists have h fossils found foss sils off skeletons, eggs, footprints – and even dinosaur poo! 7
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2 Age of the Dinosaurs Thanks to all the fossil discoveries, scientists know when dinosaurs first appeared on Earth and when they disappeared. They call this the Age of the Dinosaurs. It is split into three different periods of time called eras. The first part is called the Triassic era. This is when the first dinosaurs appeared, such as the Postosuchus. Postosuchus
252–201 million years ago
201–145 million years ago
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Plus
Lime Plus Band 11+
Why did dinosaurs become extinct?
Why did dinosaurs become extinct? WHY DID DINOSAURS BECOME EXTINCT?
Dinosaurs have been fascinating people for many years. Why and how did such powerful reptiles become extinct so suddenly? It is a puzzle that has mystified scientists for a long time. Help us to study the evidence and solve the puzzle!
An information book collins.co.uk/collinsbigcat
85665_Cover.indd 1
Claire Llewellyn 29/10/2021 15:05