Jurassic Period
A Jurassic Period is a geologic period that extends from the end of the Triassic 201.3± 0.6 Ma to the beginning of the Cretaceous 145± 4 Ma.
- Context:
- It ends with the Triassic–Jurassic Extinction Event.
- See: Triassic, Cretaceous, Mesozoic Era, Extinction, Toarcian Turnover, Tithonian, European Alps, Limestone, Supercontinent.
References
2014
- (Wikipedia, 2014) ⇒ http://en.wikipedia.org/wiki/Jurassic Retrieved:2014-9-27.
- The Jurassic (from Jura Mountains of the Alps) is a geologic period and system that extends from Ma (million years ago) to Ma; from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles. The start of the period is marked by the major Triassic–Jurassic extinction event. Two other extinction events occurred during the period: the Late Piensbachian/Early Toarcian event in the Early Jurassic, and the Late Tithonian event at the end; however, neither event ranks among the 'Big Five' mass extinctions. The Jurassic is named after the Jura Mountains within the European Alps, where limestone strata from the period were first identified.
By the beginning of the Jurassic, the supercontinent Pangaea had begun rifting into two landmasses, Laurasia to the north and Gondwana to the south. This created more coastlines and shifted the continental climate from dry to humid, and many of the arid deserts of the Triassic were replaced by lush rainforests. On land, the fauna transitioned from the Triassic fauna, dominated by both dinosauromorph and crocodylomorph archosaurs, to one dominated by dinosaurs alone. The first birds also appeared during the Jurassic, having evolved from a branch of theropod dinosaurs. Other major events include the appearance of the earliest lizards, and the evolution of therian mammals, including primitive placentals. Crocodylians made the transition from a terrestrial to an aquatic mode of life. The oceans were inhabited by marine reptiles such as ichthyosaurs and plesiosaurs, while pterosaurs were the dominant flying vertebrates.
- The Jurassic (from Jura Mountains of the Alps) is a geologic period and system that extends from Ma (million years ago) to Ma; from the end of the Triassic to the beginning of the Cretaceous. The Jurassic constitutes the middle period of the Mesozoic Era, also known as the Age of Reptiles. The start of the period is marked by the major Triassic–Jurassic extinction event. Two other extinction events occurred during the period: the Late Piensbachian/Early Toarcian event in the Early Jurassic, and the Late Tithonian event at the end; however, neither event ranks among the 'Big Five' mass extinctions. The Jurassic is named after the Jura Mountains within the European Alps, where limestone strata from the period were first identified.