The Jurassic Period
Dawn began to break over the sleeping swamp.
Golden sunlight poured through the wispy mist that hung low over the damp
ground. Moisture dripped from the
great leaves of the cycads. The
morning calls of the swamp’s inhabitants filled the humid air.
Ferns crashed and rustled as a small dinosaur bounded through them on its
way to drink at the water’s edge. Morning
had come to the swamp, and the moist air was filled with the sounds of life. 
What the Weather Was
What Was Growing
How Do We Know That?
Mesozoic Timeline
The Jurassic period occurred during the middle
of the Mesozoic Era, the Age of Dinosaurs.
It began after the Triassic period, and was followed by the Cretaceous
period. The Jurassic period began
206 million years ago and ended about 144 million years ago.
How the Earth Moved
During the Jurassic period, the plates that
make up the Earth’s surface began to move, and the gigantic continent called
Pangaea began to break up. North
America began to drift away from South America and Africa.
The Atlantic Ocean began to form in between these two landmasses.
Most of the areas that would become North America and Europe were slowly
covered by a vast, shallow sea called the Sundance Sea.
At the same time, the breakup of Pangaea caused
many earthquakes and volcanic eruptions. These
upheavals, combined with the movements of the continents, brought about new rift
valleys, mountains and ocean ridges. The Sierra Nevada and Rocky Mountains of North America began
to form at this time.
What the Weather Was
As the movement of the Earth’s continents
brought shallow seas further inland, the planet’s climate began to change.
In previous times, most of the Earth had been like a desert.
During the Jurassic, the world became like a greenhouse.
The climate all over the Earth was warm and very moist, with no ice
anywhere.
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What
Was Growing
The greenhouse climate of the Jurassic period
encouraged the growth of a variety of vegetation.
Tall, palm-like trees called cycads were very common, as were conifers
and ginkgos. Many different
varieties of ferns covered the ground. Horsetails
were also very common. In the
fertile swamps, horsetails could grow up to 100 feet (30 meters) tall.
The plants of the Jurassic period were all non-flowering plants that
reproduced from seed, cones or spores.
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How Do We Know That?
The
Jurassic period got its name from the Jura Mountains in eastern France and
western Switzerland. The Earth’s
movements have left many expanses of Jurassic-age rocks exposed in these
mountains. Scientists have used the
Jura Mountains to study the composition of Jurassic rocks, in order to find out
more about the Earth’s structure at that time.
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Mesozoic Timeline
