Smithsonian National Museum of Natural History Geologic Time The Story of a Changing Earth
Presented by the Department of Paleobiology.
The Jurassic
Contents
Overview
Jurassic Life
Diversity in the "Age of Dinosaurs"
Flight and the Origin of Birds
Jurassic Climate and Tectonic Activity
Evidence
Skeleton of Camarasaurus
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sample
Allosaurus fragilis
Diplodocus longus
Camptosaurus dispar
Ceratosaurus nasicornus
Stegosaurus stenops
Archaeopteryx lithographica
Lytoceras cornucopiae
Promicroceras planicosta
Crocodilian
Ichthyosaur
Dragonfly
Walking stick
Norfolk Island pine
Ginkgo leaf
references and links
Foundational Concepts
Dating Methods
Earth Processes
Life Processes
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Jurassic Climate and Tectonic Activity
Pangea, which had begun forming in the Devonian (400 million years ago) and lasted through the Triassic, finally began to split apart in the Late Triassic. By the Middle and Late Jurassic, enough plate movement had occurred to separate South America from southern Africa. Laurasia (which consisted of North America and Eurasia) also moved away from Africa and South America, helping to create the Atlantic Ocean and the Gulf of Mexico. Volcanic activity was common along these rifting continental margins. At the same time, Eurasia (Europe and Asia) moved to the south and started to close off the Tethys Ocean. Sea level gradually rose during the Jurassic, creating epicontinental seaways in North America and Europe. The end result was a world with many more separate land-masses, and a great deal more coastline, than the world of the Triassic.

Much of the Jurassic world was warm and moist, with a greenhouse climate. Coal deposits formed under forests in Australia and Antarctica. Although some arid regions remained, much of the rest of Pangea was lush and green. Northern (Laurasian) and southern (Gondwanan) biotas were still distinct in many ways, but by the Jurassic, faunas had acquired a more intercontinental character. Some animals and plants were now found nearly worldwide, instead of being restricted to particular regions.



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Overview | Jurassic Life | Diversity in the “Age of Dinosaurs”
Flight and the Origin of Birds | Jurassic Climate and Tectonic Activity



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