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ZoomDinosaurs.com
The Mesozoic Era (248 - 65 million years ago) Ages of the Mesozoic Era
Triassic Period
248 - 206 mya
First dinosaurs and mammals
Jurassic Period
206-144 mya
Many dinosaurs and the first birds
Cretaceous Period
144-65 mya
First flowering plants, the height of the dinosaurs. Ends in huge extinction.
Early - Middle
248-227 mya
Late
227-206 mya
Early
(Lias)

206-180 mya
Middle
(Dogger)

180-154 mya
Late
(Malm)

154-144 mya
Early
(Neocomian)

144-127 mya
Middle
(Gallic)

127-89 mya
Late
(Senonian)

89-65 mya

THE JURASSIC PERIOD

THE BEGINNING OF THE JURASSIC

Earth 150 million years agoAt the beginning of the Jurassic, the Earth's continents were still jammed together, forming the supercontinent Pangaea, but they were beginning to drift apart. There had been a minor extinction at the end of the Triassic period, which gave rise to an abundance of dinosaurs in the Jurassic. The climate was hot and dry and at the beginning of the Jurassic, strongly seasonal.

The dinosaurs dominated the near-tropical Earth during the Jurassic, and many new groups appeared. The gigantic sauropod dinosaurs, like the Diplodocus and Apatosaurus, diversified. Carnivorous theropods, like Allosaurus and Compsognathus, were abundant. Bird-like dinosaurs also flourished.

About 140 million years ago, during the late Jurassic period, the flowering plants (angiosperms) evolved, and would soon change the face of the Earth.

There was a minor mass extinction toward the end of the early Jurassic period (roughly 190-183 million years ago) in which more than 80% of marine bivalve species (like many clams) and many other shallow-water species died out. The cause of this extinction is unknown, but there is some speculation (by sedimentologist Stephen P. Hesselbo et al.) that it was triggered by the release of huge methane deposits from within the Earth (these deposits formed beneath the seabed as surface algae dies and sinks to the sea floor).



OTHER ANIMALS AND PLANTS IN THE JURASSIC
Early mammals were developing and diversifying in the Jurassic. Some Jurassic period mammals included Morganucodontids (like Morganucodon and Megazostrodon), Haramiyids (like Haramiya), Docodonts (like Docodon), multiberculates, symmetrodonts, pantotheres, and a recently-found, mouse-sized Middle Jurassic mammal (a tribosphenidan) from Madagascar.

Also, Archaeopteryx, the first, primitive, dinosaur-like bird appeared about 150 million years ago, toward the end of the Jurassic. There were also pterosaurs , flying reptiles which were the largest vertebrates ever known to fly.

In the Jurassic seas, there were abundant coral reefs, fish, ichthyosaurs (fishlike reptiles), plesiosaurs, giant marine crocodiles , ammonites, squid , sharks and the first rays .

Plant lines from the Triassic continued. There were many tufted, palm-like cycads, seed ferns , gingkos, and conifers in the subtropical forests.



THE MIDDLE JURASSIC
In the Middle Jurassic, the supercontinent Pangaea started to drift apart. A north-south rift formed in mid-Jurassic, and by the late Jurassic, the separation of the continents of Laurasia and Gondwana was almost complete. PANGAEA

Laurasia



GEOLOGY AND CLIMATE DURING THE JURASSIC
The Jurassic period is named for rock strata found in the Jura Mountains, which are located between France and Switzerland.

There was no polar ice during the Jurassic, so the sea levels were higher than they are now. The climate was warm. Early in the Jurassic, the continents were jammed together into a supercontinent (Pangaea), making much of the inland area dry and desert-like. Towards the middle of the Jurassic, when Pangaea becgan to break up, there were vast flooded areas, temperate and subtropical forests, and coral reefs. The extensive water moderated the strong seasonality so that by the end of the Jurassic there was less seasonality than we have now.


THE END OF THE JURASSIC
Many giant sauropods (like Mamenchisaurus, pictured at the right) lived during the late Jurassic period. Conifers dominated the landscape.

There was a minor mass extinction toward the end of the Jurassic period. During this extinction, most of the stegosaurid and enormous sauropod dinosaurs died out, as did many genera of ammonoids, marine reptiles, and bivalves. No one knows what caused this extinction.

Printout:
Jurassic animal printouts

ZoomDinosaurs.com
The Mesozoic Era (248 - 65 million years ago) Ages of the Mesozoic Era
Triassic Period
248 - 206 mya
First dinosaurs and mammals
Jurassic Period
206-144 mya
Many dinosaurs and the first birds
Cretaceous Period
144-65 mya
First flowering plants, the height of the dinosaurs. Ends in huge extinction.
Early - Middle
248-227 mya
Late
227-206 mya
Early
(Lias)

206-180 mya
Middle
(Dogger)

180-154 mya
Late
(Malm)

154-144 mya
Early
(Neocomian)

144-127 mya
Middle
(Gallic)

127-89 mya
Late
(Senonian)

89-65 mya



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