Portal:Cretaceous

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The Cretaceous Portal

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Introduction

The Cretaceous ( /krɪˈt.ʃəs/, krih-TAY-shəs) is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago (mya) to the beginning of the Paleogene Period 66 mya. It is the last period of the Mesozoic Era, and the longest period of the Phanerozoic Eon. The Cretaceous Period is usually abbreviated K, for its German translation Kreide (chalk, creta in Latin).

The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas. These oceans and seas were populated with now-extinct marine reptiles, ammonites and rudists, while dinosaurs continued to dominate on land. During this time, new groups of mammals and birds, as well as flowering plants, appeared.

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Selected article on the Cretaceous world and its legacies

Map of the Chicxulub crater.
The Chicxulub crater (/ˈkʃəlb/; Mayan pronunciation: [tʃʼikʃuluɓ]) is a prehistoric impact crater buried underneath the Yucatán Peninsula in Mexico. Its center is located near the town of Chicxulub, after which the crater is named. The age of the Chicxulub asteroid impact and the Cretaceous–Paleogene boundary (K–Pg boundary) coincide precisely. The crater is more than 180 kilometres (110 mi) in diameter and 20 km (12 mi) in depth, making the feature one of the largest confirmed impact structures on Earth; the impacting bolide that formed the crater was at least 10 km (6 mi) in diameter. Evidence for the impact origin of the crater includes shocked quartz, a gravity anomaly, and tektites in surrounding areas.

The age of the rocks marked by the impact shows that this impact structure dates from roughly 66 million years ago, the end of the Cretaceous period, and the start of the Paleogene period. The impact associated with the crater is thus implicated in the Cretaceous–Paleogene extinction event, including the worldwide extinction of non-avian dinosaurs. This conclusion has been the source of controversy. In March 2010, 41 experts from many countries reviewed the available evidence: 20 years worth of data spanning a variety of fields. They concluded that the impact at Chicxulub triggered the mass extinctions at the K–Pg boundary. (see more...)

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Fossils of the Late Cretaceous ammonoids Hoploscaphites (left) und Discoscaphites (right)

Fossil shells of the scaphitid ammonoids Hoploscaphites (left) and Discoscaphites (right). The shell dates back to the Maastrichtian age (66–72.1 million years ago) of the Late Cretaceous epoch. The Specimen was collected in South Dakota, USA.
Photo credit: H. Zell

Selected article on the Cretaceous in human science, culture or economics

Jurassic Park author Michael Crichton.

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...)

Geochronology

Epochs - Early Cretaceous - Late Cretaceous
Stages - Berriasian - Valanginian - Hauterivian - Barremian - Aptian - Albian - Cenomanian - Turonian - Coniacian - Santonian - Campanian - Maastrichtian
Events - Cambrian–Ordovician extinction event - Great Ordovician Biodiversification Event - Taconic orogeny - Late Ordovician glaciation - Alice Springs Orogeny - Ordovician–Silurian extinction event

Landmasses - Baltica - Gondwana - Laurentia - Siberia
Bodies of water - Iapetus Ocean - Khanty Ocean - Proto-Tethys Ocean - Rheic Ocean - Tornquist Sea - Ural Ocean
Animals - Articulate brachiopods - Bryozoans - Cornulitids - Crinoids - Cystoids - Gastropods - Graptolites - Jawed fishes - Nautiloids - Ostracoderms - Rugose corals - Star fishes - Tabulate corals - Tentaculitids - Trilobites
Trace fossils - Petroxestes - Trypanites
Plants - Marchantiophyta

Fossil sites - Beecher's Trilobite Bed - Walcott–Rust quarry
Stratigraphic units - Chazy Formation - Fezouata formation - Holston Formation - Kope Formation - Potsdam Sandstone - St. Peter Sandstone

Researchers - Charles Emerson Beecher - Charles Lapworth - Charles Doolittle Walcott
Culture - Animal Armageddon - List of creatures in the Walking with... series - Sea Monsters

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Current Cretaceous FACs - none currently

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