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The Jurassic Portal

Introduction

The Jurassic (/dʒʊˈræsɪk/ juurr-ASS-ik) is a geologic period and stratigraphic system that spanned from the end of the Triassic Period 201.4 million years ago (Mya) to the beginning of the Cretaceous Period, approximately 145 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 (CAMP). The beginning of the Toarcian Stage started around 183 million years ago and is marked by the Toarcian Oceanic Anoxic Event, a global episode of oceanic anoxia, ocean acidification, and elevated global temperatures associated with extinctions, likely caused by the eruption of the Karoo-Ferrar large igneous provinces. The end of the Jurassic, however, has no clear, definitive 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 arid expanses in the lower latitudes. (Full article...) (Full article...)

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Selected article on the Jurassic world and its legacies

Damselflies (suborder Zygoptera) are insects in the order Odonata. They are similar to dragonflies, but are smaller, have slimmer bodies, and most species fold the wings along the body when at rest. Damselflies are an ancient group, having existed since at least the Lower Permian. Today they are found on every continent except Antarctica.

All damselflies are predatory; both nymphs and adults eat other insects. The nymphs are aquatic, with different species living in a variety of freshwater habitats including acid bogs, ponds, lakes and rivers. The nymphs moult repeatedly, at the last moult climbing out of the water to undergo metamorphosis. The skin splits down the back, they emerge and inflate their wings and abdomen to gain their adult form.

Some species of damselfly have elaborate courtship behaviours. Many species are sexually dimorphic, the males often being more brightly coloured than the females. Like dragonflies, they reproduce using indirect insemination and delayed fertilisation. A mating pair form a shape known as a "heart" or "wheel", the male clasping the female at the back of the head, the female curling her abdomen down to pick up sperm from secondary genitalia at the base of the male's abdomen. The pair often remain together with the male still clasping the female while laying eggs within the tissue of plants in or near water using a robust ovipositor. (see more...)

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Selected article on the Jurassic in human science, culture and economics

Jurassic Park is a 1993 American science fiction adventure film directed by Steven Spielberg. It is the first installment of the Jurassic Park franchise. It is based on the 1990 novel of the same name by Michael Crichton, with a screenplay written by Crichton and David Koepp. The film centers on the fictional Isla Nublar, an islet located off Central America's Pacific Coast, near Costa Rica Nicaragua border, where a billionaire philanthropist and a small team of genetic scientists have created a wildlife park of cloned dinosaurs.

Following an extensive $65 million marketing campaign, which included licensing deals with 100 companies, Jurassic Park grossed over $900 million worldwide in its original theatrical run. It surpassed Spielberg's 1982 film E.T. the Extra-Terrestrial to become the highest-grossing film until Titanic (1997). Jurassic Park was well received by critics, who praised its special effects and Spielberg's direction but criticized the script. The film won more than 20 awards (including 3 Academy Awards), mostly for its visual effects. Jurassic Park is considered by many to be one of the greatest films of the 1990s and in some cases of all time, as well as a landmark in the vector of visual effects regarding its computer-generated imagery and animatronics.

Jurassic Park was followed by two sequels, The Lost World: Jurassic Park and Jurassic Park III, both of which were box office successes but received mixed critical responses. A third sequel, Jurassic World, is set for release on June 12, 2015. (see more...)

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A fossil shell of the harpoceratid ammonoid Ochetoceras canaliculatum. The shell dates back to the Oxfordian age (157.3–163.5 million years ago) of the Late Jurassic epoch and is about 9 cm in diameter. It was collected near Wildegg, Switzerland.
Photo credit: H. Zell

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Did you know?

... that over the course of the history of stegosaur research, their iconic back plates have been thought to function as armor plating, to regulate body temperature, or to attract mates?
... that the ammonite Hildoceras bifrons (pictured) has been used as an index fossil to help identify the age of rocks?
...that the prehistoric marine reptile Excalibosaurus (pictured) was named after King Arthur's sword because of the sword-like appearance of its upper jaw?
... that the extinct hangingfly genera Formosibittacus, Jurahylobittacus, and Mongolbittacus are only known from the Middle Jurassic of China?
... that Shantungosuchus, a small, primitive crocodile from the Cretaceous period, was terrestrial instead of aquatic?