First Children Encyclopedia

(Marvins-Underground-K-12) #1

Earth has an incredibly long history, as


it formed about 4,600 million years ago.


Geologists divided the passage of


time since then into huge


chunks called eras.


The dinosaurs


lived in the


Mesozoic Era.


Age of the dinosaurs

A question of time
Different dinosaurs lived at different
times, and many of the best-known
dinosaurs never actually met. For
example, no T. rex ever tried to kill a
Stegosaurus because their existence was
separated by about 80 million years.

Age of the dinosaurs


Triassic: 248 to 206 million years ago Jurassic: 206 to 144 million years ago


MESOZOIC ERA


182
How do we know what dinosaurs looked like?


Eoraptor Plateosaurus

Coelophysis
Brachiosaurus
Stegosaurus
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