Mesozoic Era
Precambrian Eon

4,600 - 541 mya

Paleozoic EraPaleozoic.html
541 - 252 myaPaleozoic.html
Mesozoic Era

252 - 66 mya

Cenozoic EraCenozoic.html
66 mya - presentCenozoic.html
Triassic Period
Jurassic Period
Cretaceous Period

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  1. BulletTriassic Period: 248 - 206 million years ago

Climate: Warm and dry

Famous Animals: Coelophysis, Eoraptor

About: Following a devastating extinction that eliminated most of Earth’s life at the end of the Permian period, the Triassic marks the beginning of a new era.  This is also when the first dinosaurs evolved, lived and survived, becoming one of the most dominant animal groups for millions of years.

  1. BulletJurassic Period: 206 - 144 million years ago

Climate: The early Jurassic was still quite arid, but as the landmasses centered themselves over the equator, conditions became mostly tropical.

Famous Animals: Allosaurus, Stegosaurus

About: The Jurassic was a time of abundance for the dinosaurs.  Large, long-necked sauropods lived all over the world, and armored dinosaurs like Stegosaurus lived amongst predators like Allosaurus, Torvosaurus, and Ceratosaurus.

  1. BulletCretaceous Period: 144 - 65 million years ago

Climate: For the most part, it was very warm, but seasonal changes became more extreme, forcing animals to migrate from year to year.

Famous Animals: Tyrannosaurus, Triceratops

About: During the Cretaceous, the landmasses began to break apart and resemble how they look today.  Long-necked sauropods still flourished in South America, and in North America large herds of duck-billed ornithopods and horned ceratopsians dominated.  Of course, they lived alongside famous predators like Tyrannosaurus and its close relatives.  This is also when the first flowering plants evolved.


  1. Smithsonian National Museum of Natural History. (2013). Geologic Time: The story of a changing earth. Retrieved from

  2. University of California Museum of Paleontology. (May, 2011). Geologic time scale. Retrieved from

  3. International Commission on Stratigraphy. (Jan, 2013). International chronostratigraphic chart. Retrieved from

  4. Public Broadcasting Station. (2001). Deep time. Retrieved from