Introducing the “Terrible Lizard”
One of the most fascinating creatures to ever roam the Earth was the dinosaur. You most likely have heard
of dinosaurs, seen pictures of them on TV or the Internet, or may have seen their bones in a museum.
Dinosaurs are an interesting group of animals that no longer exist, meaning they are extinct.
Dinosaurs evolved, meaning they changed, over millions of years. All animals change over time.
The word dinosaur was first used in 1842 by an English biologist (a person who studies life), Sir Richard
Owen. He needed a new word for a group of animals he identified and used the word Dinosauria. The word
comes from two other words that means terrible lizard. However, dinosaurs are not lizards but are reptiles.
Sometimes early birds were also referred to as dinosaurs.
Dinosaurs first lived over 200 million years ago but they died out about 66 million years ago. The time-period
they lived during is called the Mesozoic Era, which is also called the Age of Reptiles. The era is divided
into three smaller periods:
• Triassic: The earliest dinosaurs appeared, but they were small and walked on two legs. During this
period, an extinction took place and the period ended.
• Jurassic: The climate was hot and humid and there were many rainforests appearing. The
dinosaurs were the dominant (main) animals with backbones called vertebrates.
• Cretaceous: Dinosaurs continued to survive until another extinction took place. However, the flying
“dinosaurs” technically called birds, survived. The dinosaurs lasted about 170 million years.
By comparison, human beings have only lived for about 200,000 years on Earth. It is like people surviving
on Earth for 4 days, but dinosaurs living for almost one year.
The remains of dinosaurs have been found on every continent. This is because millions of years ago the
continents were joined together and there was one supercontinent called Pangaea. The dinosaurs easily
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roamed the land moving from place to place because the oceans
did not separate the continents.
Once the continents separated, the oceans prevented dinosaurs
from moving between continents. Climates throughout the world
changed as well. The Earth began to cool and there was more
rain. During the last two periods of the Mesozoic Era, the land
separated to its present form today.
The dinosaurs’ extinction took place about 66 million years ago 75%
of all life on Earth died. There are many theories or guesses as to
what may have happened leading to the extinction. They include
worldwide volcanic eruptions, changes in the Earth’s climate, or
perhaps a meteorite from space smashing into the Earth.