Jurassic
The Jurassic ( ) is a geologic period and stratigraphic system that spanned from the end of the Triassic period million years ago (Mya) to the beginning of the Cretaceous period, approximately Mya. The Jurassic constitutes the middle period of the Mesozoic era and is named after the Jura Mountains, where limestone strata from the period were first identified.

The start of the Jurassic was marked by the major Triassic–Jurassic extinction event, associated with the eruption of the Central Atlantic Magmatic Province. The beginning of the Toarcian stage started around 183 million years ago, and is marked by an extinction event associated with widespread oceanic anoxia, ocean acidification, and elevated the temperatures likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear boundary with the Cretaceous and is the only boundary between geological periods to remain formally undefined.

By the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses: Laurasia to the north and Gondwana to the south. The climate of the Jurassic was warmer than the present, and there were no ice caps. Forests grew close to the poles, with large expanses of desert in the lower latitudes.

On land, the fauna transitioned from the Triassic fauna, dominated jointly by dinosauromorph and pseudosuchian archosaurs, to one dominated by dinosaurs alone. The first birds appeared during the Jurassic, evolving from a branch of theropod dinosaurs. Other major events include the appearance of the earliest lizards and the evolution of therian mammals. Crocodylomorphs made the transition from a terrestrial to an aquatic life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, while pterosaurs were the dominant flying vertebrates.
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geologic period
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stratigraphic system
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Triassic
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Q44626
Cretaceous
TIME
Q83222
Mesozoic era
TIME
Q178611
Jura Mountains
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Q23757
limestone
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Triassic–Jurassic extinction event
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Central Atlantic Magmatic Province
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Toarcian
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oceanic anoxia
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ocean acidification
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Q6373242
Karoo-Ferrar large igneous provinces
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Q55833
supercontinent
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Pangaea
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rift
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Q132033
Laurasia
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Gondwana
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ice caps
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dinosauromorph
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pseudosuchia
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archosaur
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Q430
dinosaur
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theropod
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Q130942
theria
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Q131863
Crocodylomorphs
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marine reptiles
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Q194515
ichthyosaur
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Q269195
plesiosaur
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pterosaur
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vertebrates
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Jurassic
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Jurassic
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Jurassic
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Jurassic
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Jurassic
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Q45805
Jurassic
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Jurassic
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Jurassic
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