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Image that says Geologic Time. Image of the Earth during the Mesozoic Era.

Mesozoic ("Middle Life") Era
This is the second of three geologic eras squeezed into the Phanerozoic ("Evident Life") Eon that covers the last 10% of Earth's whole geologic history. This is the era we all think of when we imagine the Ancient Earth! Rampaging dinosaurs! Dive-bombing pterodactyls! Endless forests of giant ferns! Erupting Volcanoes! (Sorry, no cave men! They didn't show up until the end of the Cenozoic.)

The Mesozoic Era lasted about 180 million years, from about 245 million years ago to about 65 million years ago. The Mesozoic is divided into just three time periods: the Triassic, the Jurassic, and the Cretaceous. Since lots of things were going on in each time period, we can only summarize the events. You can learn more by going to your library or searching the Internet for words like "Mesozoic" or the names of each of the periods.

In the view above, we see Earth in the middle of the Jurassic Period, in mid-Mesozoic times (sort of a middle-middle view). The supercontinents Gondwanaland and Laurasia collided some time back to form a single super-super continent called Pangea ("All-Earth"). But plate tectonics continues its irresistible motions, and even as we look, Pangea is beginning to break up into the continents we know now. At upper left, North America is just breaking away from the northwest coast of Africa, and the Atlantic Ocean and Gulf of Mexico are beginning to form. The Appalachian Mountains of the eastern United States are a high, rugged mountain range, something like the Rocky Mountains of today. Over the next fifty million years or so, South America, India, and Antarctica will all break away from Africa and move toward their present positions.

Life is diversifying rapidly, and beginning to look familiar. The dominant animals on both land and sea are reptiles, the most famous of which are the dinosaurs. Dinosaurs began in the Triassic, spread during the Jurassic, and dominated Earth in the Cretaceous. They are so prominent that the Mesozoic is also called "The Age of Reptiles." But dinosaurs are not the only life form around: birds and mammals also appear during the Mesozoic, as well as deciduous trees and flowering plants.

The climate during the Mesozoic is warm; so warm that there are no ice caps at all, even at the poles! Plants grow like crazy in the warmth and moisture, so there is food everywhere for your average hungry 50-ton Ultrasaurus! So what happened to this Dino Paradise? More change! A mass extinction like those in the Paleozoic ended the idyllic Mesozoic Era (if you can call dodging your friendly local T-Rex as idyllic). More than half of all existing life forms disappeared, including virtually all of the dinosaurs. Why? There are many hypotheses, including disease, volcanic eruptions, and giant impacts. (Pay a visit to the Dinosaur Floor to learn more.

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Geologic Time
Cenozoic Era
Image of a star. Mesozoic Era
Paleozoic Era
The Precambrian Eon
Names on the Staircase of Time
How Old is That Rock?
Geologic Time Activity
What is a Million?
Finding an Event in Time
 
             
     
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Geologic Time | Cenozoic Era | Mesozoic Era | Paleozoic Era | The Precambrian Eon | The Staircase of Time | How Old is That Rock? | Geologic Time Activity | What is a Million? | Finding a Place in Time

Diversity | Adaptation | Plate Tectonics | Cycles | Spheres | Biomes | Geologic Time

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April 28, 2005

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