Cretaceous

• 白亜紀の

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Cretaceous period

　 　 　

WordNet

1. of or relating to or denoting the third period of the Mesozoic era
2. from 135 million to 63 million years ago; end of the age of reptiles; appearance of modern insects and flowering plants (同)Cretaceous_period
3. abounding in chalk

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1. 白亜紀[系](中生代に属し,巨大爬虫(はちゅう)類の消滅と昆虫の出現が特徴) / 白亜紀[系]の

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2012/10/25 17:14:00」(JST)

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地質時代区分

顕 生 代	新 生 代	第四紀
		新第三紀
		古第三紀
	中 生 代	白亜紀
		ジュラ紀
		三畳紀
	古 生 代	ペルム紀
		石炭紀
		デボン紀
		シルル紀
		オルドビス紀
		カンブリア紀
原生代
始生代
冥王代

白亜紀（白堊紀、はくあき、Cretaceous period）とは、地球の地質時代のひとつで、およそ1億4550万年前から6550万年前を指す。ジュラ紀に続く時代であり中生代の終わりの時代でもある。次の時代は新生代古第三紀の暁新世である。

白堊の堊（アク; アとよむのは慣習）は粘土質な土、則ち石灰岩のことであり、石灰岩の地層から設定された地質年代のため白堊紀の名がついた。白堊を白亜とするのは常用漢字にないからで、亜（亞）には土の意味は無い。

概要

白亜紀は温暖な気候と高海水準で特徴付けられる時代である。他の地質時代と同様に白亜紀の開始と終了の地層には際立った特徴があるものの、正確な年代については、数百万年程度の誤差が見受けられる。白亜紀の終わりを示すK-T境界においては、イリジウムが大量に含まれた粘土層が世界中に見つかっている。これは、6,568万年前にユカタン半島およびメキシコ湾にある巨大なチクシュルーブ・クレーターを作った隕石の衝突によりその破片が地上に降り積もった物と考えられている。この隕石の落下が引き起こした気候変動が、白亜紀末の大量絶滅に関係あるという学説は、現在では地質学者、古生物学者らの間で広く支持されている。

白亜紀は以下のように11の時代に分けられている。

白亜紀と周辺の地質時代

周辺の時代
新生代	第四紀
	新第三紀
	古第三紀	漸新世
		始新世
		暁新世
中生代	白亜紀		マストリヒシアン（マーストリヒト期）	7060万年 - 6550万年前
			カンパニアン（カンパン期）	8350万年 - 7060万年前
			サントニアン（サントン期）	8580万年 - 8350万年前
			コニアシアン（コニアク期）	8930万年 - 8580万年前
			チューロニアン（チューロン期）	9350万年 - 8930万年前
			セノマニアン（セノマン期）	9960万年 - 9350万年前
			アルビアン（アルブ期）	1億1200万年 - 9960万年前
			アプチアン（アプト期）	1億2500万年 - 1億1200万年前
			バレミアン（バーレム期）	1億3000万年 - 1億2500万年前
			オーテリビアン（オーテリーブ期）	1億3640万年 - 1億3000万年前
			バランギニアン（バランジュ期）	1億4020万年 - 1億3640万年前
			ベリアシアン（ベリアス期）	1億4550万年 - 1億4020万年前
	ジュラ紀
	三畳紀
古生代

気候と生物

気候

ジュラ紀から白亜紀の境目に大きな絶滅などはなく、白亜紀も長期にわたり温暖で湿潤な気候が続いた。前期白亜紀において、一時的な寒冷化が見られるものの、同時期の表層海水温に関する研究では、低緯度地域で32 ℃、中緯度地域で26 ℃と現在より高い海水温で安定していたことがわかっている。末期には気候帯が現われ、植物相にも変化が見られた。

植物

植物は主流であった原始的な裸子植物やシダなどが減少し、被子植物が主流となって進化、繁栄を遂げた。スギなどの針葉樹は現代と同じ形まで進化し、イチジクやスズカケノキ、モクレンなどが現在とほぼ同じ形となった。

地上動物

地上の動物は恐竜やワニなどの爬虫類が支配的地位を占め、ジュラ紀に続いて全盛期であった。地上、海洋、空を含め多種多様な進化を遂げている。代表的な種は、ティラノサウルス、トリケラトプス、プテラノドンなど。しかし末期には恐竜は衰退を始める（後述）。また、白亜紀後期には鳥類の発展と対照的に中・小型の翼竜類が衰え、プテラノドンやケツァルコアトルスなど大型種だけが残った。有鱗目 においてヘビ類が地中性もしくは水中性のトカゲ類から進化したのも、白亜紀であるとされる。

哺乳類はこの時代に形態を大きく進化させ、胎生を持つようになり、また有袋類と有胎盤類への分化を遂げた。中には恐竜の幼体を襲っていた種もある。ただし形態は小さな形の種にとどまっていたものが多い。有胎盤類は白亜紀後期には既に多くの系統へと分岐していたようである。

前時代に恐竜から分岐した鳥類ではこの時代に真鳥類が出現している。しかし大勢を占めたのは古鳥類であり、陸上性では孔子鳥やエナンティオルニス類 (反鳥類,Enantiornithes) が繁栄した。なお、海鳥では真鳥類のヘスペロルニス・イクチオルニスなどが栄えた。しかし白亜紀に全盛を迎えたこれらの鳥類のグループは白亜紀末期にほとんどが絶滅した。この時期に現生鳥類の直系の祖先も出現している。多くの目は白亜紀後期には分化していたようだ。

海洋動物

海洋では1億2000万年前に現在のオントンジャワ海台を形成した大規模な海底火山噴火が南太平洋で発生した。魚竜、海生ワニ類が絶滅したのは、この影響ともされる。代わってモササウルス類、首長竜などが繁栄した。軟骨魚類では現在見られる型のエイやサメ、硬骨魚類ではニシン類が現れ、軟体動物では狭義のアンモナイトなどが進化を遂げた。

ジュラ紀中期に誕生した浮遊性有孔虫およびココリスなどのナンノプランクトンは、この時期に生息域を大きく拡大させ、その遺骸は白亜紀の名称の元となった石灰岩層を形成した。

K-T境界の大量絶滅

詳細は「K-T境界」を参照

地上・空・海で繁栄していた爬虫類も、白亜紀の末には減り始めた。

白亜紀末には、地球史の上で5回目の、規模としては古生代ペルム紀末期の大絶滅（P-T境界）に次ぐ大規模な絶滅が起きた（K-T境界）。この大量絶滅では、陸上生物の約50%、海洋生物の約75%、生物全体で約70％が絶滅したと考えられている。哺乳類・爬虫類・鳥類の多くが絶滅し、特に恐竜は（現生種につながる真鳥類を除いて）全てが絶滅した。また、海洋においても、カメ、カンプソサウルス（チャンプソサウルス）類以外の全ての海棲爬虫類、すべてのアンモナイト類が絶滅している。しかし、アメリカで、この大量絶滅から70万年後とされる地層からアラモサウルスの化石が発見され、議論を呼んでいる。この発見は、カナダのアルバータ大学などの研究により確認され、論文がアメリカ地質学協会の専門誌に掲載された。

現在では絶滅の直接の原因は隕石（小惑星）の衝突によるものであるという説が広く知られており、2010年3月5日には12ヶ国の研究機関による研究チームが同説が絶滅の直接の原因であると結論づけた。ただし、それ以外の説も依然として存在する。

地質

白亜紀の終わりにかけて、パンゲア大陸は完全に分かれ、配置は異なるものの現在ある大陸と同じ構成になった。北アメリカとヨーロッパがわかれ大西洋が広がり、ゴンドワナ大陸は南極大陸、オーストラリア大陸、アフリカ大陸、南アメリカ大陸に分割した。インドやマダガスカルはまだアフリカと陸続きであった。北アメリカ大陸に食い込むようにしてあった浅い海は石炭層に挟まれて陸地となり、海の堆積物を多く残した。この他で重要な白亜紀の地層の露出は中国とヨーロッパで見られる。また、インドのデカントラップにある大量の溶岩の地層は白亜紀から暁新世にかけての物ということがわかっている。

脚注

参考文献

• Thierstein, H.R. (1982). “Terminal Cretaceous plankton extinctions: A critical assesment.”. Geol. Soc. Am. Special Paper 190: 385-399. 
• Sheehan, P.M.; Fastovsky,D.E. (1992). “Major extinctions of land-dwelling vertebrates at the Cretaceous-Tertiary boundary, eastern Montana.”. Geology 20: 556-560. 
• ジェームズ・ローレンス・パウエル 『白亜紀に夜がくる-恐竜の絶滅と現代地質学』 寺嶋英志・瀬戸口烈司訳、青土社、2001年。ISBN 4791759079。
• Littler, Kate; Robinson, Stuart A., Bown, Paul R., Nederbragt, Alexandra J., Pancost, Richard D. (2011). “High sea-surface temperatures during the Early Cretaceous Epoch”. nature geoscience 4 (3): 169-172. doi:10.1038/NGEO1081. 

関連項目

• 地質時代 - 顕生代 - 中生代

外部リンク

• 仲田崇志 (2009年10月29日). “地質年代表”. きまぐれ生物学. 2011年2月14日閲覧。

wiki en

[Wiki en表示]

Cretaceous Period 145.5–65.5 million years ago PreЄ Є O S D C P T J K Pg N
Mean atmospheric O2 content over period duration	ca. 30 Vol % (150 % of modern level)
Mean atmospheric CO2 content over period duration	ca. 1700 ppm (6 times pre-industrial level)
Mean surface temperature over period duration	ca. 18 °C (4 °C above modern level)

The Cretaceous ( /krɨˈteɪʃəs/, krə-TAY-shəs), derived from the Latin "creta" (chalk), usually abbreviated K for its German translation Kreide (chalk), is a geologic period and system from circa 145.5 ± 4 to 65.5 ± 0.3 million years (Ma) ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the Cenozoic era. It is the last period of the Mesozoic Era, and, spanning 80 million years, the longest period of the Phanerozoic Eon.

The Cretaceous was a period with a relatively warm climate, resulting in high eustatic sea levels and creating 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. At the same time, new groups of mammals and birds, as well as flowering plants, appeared. The Cretaceous ended with a large mass extinction, the Cretaceous–Paleogene extinction event, in which many groups, including non-avian dinosaurs, pterosaurs, and large marine reptiles, died out. The end of the Cretaceous is defined by the K–Pg boundary, a geologic signature associated with the mass extinction which lies between the Mesozoic and Cenozoic Eras.

Geology

Key events in the Cretaceous

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Maastrichtian

Campanian

Santonian

Coniacian

Turonian

Cenomanian

Albian

Aptian

Barremian

Hauterivian

Valanginian

Berriasian

Jurassic

Paleogene

 

 

 

 

 

 

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 Mesozoic
 Cenozoic

An approximate timescale of key Cretaceous events.
Axis scale: millions of years ago.

Research history

The Cretaceous as a separate period was first defined by a Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris Basin and named for the extensive beds of chalk (calcium carbonate deposited by the shells of marine invertebrates, principally coccoliths), found in the upper Cretaceous of western Europe. The name Cretaceous was derived from Latin creta, meaning chalk. The name of the island Crete has the same origin.

Stratigraphic subdivisions

The Cretaceous is divided into Early and Late Cretaceous epochs or Lower and Upper Cretaceous series. In older literature the Cretaceous is sometimes divided into three series: Neocomian (lower/early), Gallic (middle) and Senonian (upper/late). A subdivision in eleven stages, all originating from European stratigraphy, is now used worldwide. In many parts of the world, alternative local subdivisions are still in use.

As with other older geologic periods, the rock beds of the Cretaceous are well identified but the exact ages of the system's top and base are uncertain by a few million years. No great extinction or burst of diversity separates the Cretaceous from the Jurassic. However, the top of the system is sharply defined, being placed at an iridium-rich layer found worldwide that is believed to be associated with the Chicxulub impact crater in Yucatan and the Gulf of Mexico. This layer has been tightly dated at 65.5 Ma.

Rock formations

Drawing of fossil jaws of Mosasaurus hoffmanni, from the Maastrichtian of Dutch Limburg, by Dutch geologist Pieter Harting (1866).

The high eustatic sea level and warm climate of the Cretaceous meant a large area of the continents was covered by warm shallow seas. The Cretaceous was named for the extensive chalk deposits of this age in Europe, but in many parts of the world, the Cretaceous system consists for a major part of marine limestone, a rock type that is formed under warm, shallow marine circumstances. Due to the high sea level there was extensive accommodation space for sedimentation so that thick deposits could form. Because of the relatively young age and great thickness of the system, Cretaceous rocks crop out in many areas worldwide.

Chalk is a rock type characteristic for (but not restricted to) the Cretaceous. It consists of coccoliths, microscopically small calcite skeletons of coccolithophores, a type of algae that prospered in the Cretaceous seas.

In northwestern Europe, chalk deposits from the Upper Cretaceous are characteristic for the Chalk Group, which forms the white cliffs of Dover on the south coast of England and similar cliffs on the French Normandian coast. The group is found in England, northern France, the low countries, northern Germany, Denmark and in the subsurface of the southern part of the North Sea. Chalk is not easily consolidated and the Chalk Group still consists of loose sediments in many places. The group also has other limestones and arenites. Among the fossils it contains are sea urchins, belemnites, ammonites and sea reptiles such as Mosasaurus.

In southern Europe, the Cretaceous is usually a marine system consisting of competent limestone beds or incompetent marls. Because the Alpine mountain chains did not yet exist in the Cretaceous, these deposits formed on the southern edge of the European continental shelf, at the margin of the Tethys Ocean.

Stagnation of deep sea currents in middle Cretaceous times caused anoxic conditions in the sea water. In many places around the world, dark anoxic shales were formed during this interval. These shales are an important source rock for oil and gas, for example in the subsurface of the North Sea.

Paleogeography

During the Cretaceous, the late-Paleozoic-to-early-Mesozoic supercontinent of Pangaea completed its tectonic breakup into present day continents, although their positions were substantially different at the time. As the Atlantic Ocean widened, the convergent-margin orogenies that had begun during the Jurassic continued in the North American Cordillera, as the Nevadan orogeny was followed by the Sevier and Laramide orogenies.

Geography of the Contiguous US in the late Cretaceous period

Though Gondwana was still intact in the beginning of the Cretaceous, it broke up as South America, Antarctica and Australia rifted away from Africa (though India and Madagascar remained attached to each other); thus, the South Atlantic and Indian Oceans were newly formed. Such active rifting lifted great undersea mountain chains along the welts, raising eustatic sea levels worldwide. To the north of Africa the Tethys Sea continued to narrow. Broad shallow seas advanced across central North America (the Western Interior Seaway) and Europe, then receded late in the period, leaving thick marine deposits sandwiched between coal beds. At the peak of the Cretaceous transgression, one-third of Earth's present land area was submerged.

The Cretaceous is justly famous for its chalk; indeed, more chalk formed in the Cretaceous than in any other period in the Phanerozoic. Mid-ocean ridge activity—or rather, the circulation of seawater through the enlarged ridges—enriched the oceans in calcium; this made the oceans more saturated, as well as increased the bioavailability of the element for calcareous nanoplankton. These widespread carbonates and other sedimentary deposits make the Cretaceous rock record especially fine. Famous formations from North America include the rich marine fossils of Kansas's Smoky Hill Chalk Member and the terrestrial fauna of the late Cretaceous Hell Creek Formation. Other important Cretaceous exposures occur in Europe (e.g., the Weald) and China (the Yixian Formation). In the area that is now India, massive lava beds called the Deccan Traps were erupted in the very late Cretaceous and early Paleocene.

Climate

The Berriasian epoch showed a cooling trend that had been seen in the last epoch of the Jurassic. There is evidence that snowfalls were common in the higher latitudes and the tropics became wetter than during the Triassic and Jurassic. Glaciation was however restricted to alpine glaciers on some high-latitude mountains, though seasonal snow may have existed farther south. Rafting by ice of stones into marine environments occurred during much of the Cretaceous but evidence of deposition directly from glaciers is limited to the Early Cretaceous of the Eromanga Basin in southern Australia.

After the end of the Berriasian, however, temperatures increased again, and these conditions were almost constant until the end of the period. This trend was due to intense volcanic activity which produced large quantities of carbon dioxide. The production of large quantities of magma, variously attributed to mantle plumes or to extensional tectonics, further pushed sea levels up, so that large areas of the continental crust were covered with shallow seas. The Tethys Sea connecting the tropical oceans east to west also helped in warming the global climate. Warm-adapted plant fossils are known from localities as far north as Alaska and Greenland, while dinosaur fossils have been found within 15 degrees of the Cretaceous south pole.

A very gentle temperature gradient from the equator to the poles meant weaker global winds, contributing to less upwelling and more stagnant oceans than today. This is evidenced by widespread black shale deposition and frequent anoxic events. Sediment cores show that tropical sea surface temperatures may have briefly been as warm as 42 °C (107 °F), 17 °C ( 31 °F) warmer than at present, and that they averaged around 37 °C (99 °F). Meanwhile deep ocean temperatures were as much as 15 to 20 °C (27 to 36 °F) higher than today's.

Further information: Cool tropics paradox

Life

Although the first representatives of leafy trees and true grasses emerged in the Cretaceous, the flora was still dominated by conifers like Araucaria (Here: Modern Araucaria araucana in Chile).

Flora

Flowering plants (angiosperms) spread during this period, although they did not become predominant until the Campanian stage near the end of the epoch. Their evolution was aided by the appearance of bees; in fact angiosperms and insects are a good example of coevolution. The first representatives of many leafy trees, including figs, planes and magnolias, appeared in the Cretaceous. At the same time, some earlier Mesozoic gymnosperms like conifers continued to thrive; pehuéns (monkey puzzle trees, Araucaria) and other conifers being notably plentiful and widespread. Some fern orders such as Gleicheniales appeared as early in the fossil record as the Cretaceous, and achieved an early broad distribution. Gymnosperm taxa like Bennettitales died out before the end of the period.^{[citation needed]}

Terrestrial fauna

On land, mammals were a small and still relatively minor component of the fauna. Early marsupial mammals evolved in the Early Cretaceous, with true placentals emerging in the Late Cretaceous period. The fauna was dominated by archosaurian reptiles, especially dinosaurs, which were at their most diverse stage. Pterosaurs were common in the early and middle Cretaceous, but as the Cretaceous proceeded they faced growing competition from the adaptive radiation of birds, and by the end of the period only two highly specialized families remained.

The Liaoning lagerstätte (Chaomidianzi formation) in China provides a glimpse of life in the Early Cretaceous, where preserved remains of numerous types of small dinosaurs, birds, and mammals have been found. The coelurosaur dinosaurs found there represent types of the group Maniraptora, which is transitional between dinosaurs and birds, and are notable for the presence of hair-like feathers.

Insects diversified during the Cretaceous, and the oldest known ants, termites and some lepidopterans, akin to butterflies and moths, appeared. Aphids, grasshoppers, and gall wasps appeared.

• Tyrannosaurus rex, one of the largest land predators of all time, lived during the late Cretaceous.

• Up to 2 m-long Velociraptor was likely feathered and roamed the late Cretaceous.

• Triceratops is one of the most recognizable genera of the Cretaceous.

• Mammals were a minor part of the Cretacean fauna with Eomaia being the first eutherian.

• A pterosaur, Anhanguera piscator

Marine fauna

In the seas, rays, modern sharks and teleosts became common. Marine reptiles included ichthyosaurs in the early and middle of the Cretaceous (becoming extinct during the late Cretaceous Cenomanian-Turonian anoxic event), plesiosaurs throughout the entire period, and mosasaurs appearing in the Late Cretaceous.

Baculites, an ammonite genus with a straight shell, flourished in the seas along with reef-building rudist clams. The Hesperornithiformes were flightless, marine diving birds that swam like grebes. Globotruncanid Foraminifera and echinoderms such as sea urchins and starfish (sea stars) thrived. The first radiation of the diatoms (generally siliceous, rather than calcareous) in the oceans occurred during the Cretaceous; freshwater diatoms did not appear until the Miocene. The Cretaceous was also an important interval in the evolution of bioerosion, the production of borings and scrapings in rocks, hardgrounds and shells (Taylor and Wilson, 2003).

• A scene from the early Cretaceous: a Woolungasaurus is attacked by a Kronosaurus.

• Tylosaurus was the largest known mosasaur, carnivorous marine reptiles that emerged in the late Cretaceous.

• Strong-swimming and toothed predatory waterbird Hesperornis roamed late Cretacean oceans.

• The ammonite Discoscaphites iris, Owl Creek Formation (Upper Cretaceous), Ripley, Mississippi.

• A plate with Nematonotus sp., Pseudostacus sp., and a partial Dercetis triqueter, found in Hakel, Lebanon

End-Cretaceous extinction event

The impact of a meteorite or comet is today widely accepted as the main reason for the Cretaceous–Paleogene extinction event.

Main article: Cretaceous–Paleogene extinction event

There was a progressive decline in biodiversity during the Maastrichtian stage of the Cretaceous period prior to the suggested ecological crisis induced by events at the K–Pg boundary (K–T boundary). Furthermore, biodiversity required a substantial amount of time to recover from the K–T event, despite the probable existence of an abundance of vacant ecological niches.

Despite the severity of this boundary event, there was significant variability in the rate of extinction between and within different clades. Species which depended on photosynthesis declined or became extinct because of the reduction in solar energy reaching the Earth's surface due to atmospheric particles blocking the sunlight. As is the case today, photosynthesizing organisms, such as phytoplankton and land plants, formed the primary part of the food chain in the late Cretaceous. Evidence suggests that herbivorous animals, which depended on plants and plankton as their food, died out as their food sources became scarce; consequently, top predators such as Tyrannosaurus rex also perished.

Coccolithophorids and molluscs, including ammonites, rudists, freshwater snails and mussels, as well as organisms whose food chain included these shell builders, became extinct or suffered heavy losses. For example, it is thought that ammonites were the principal food of mosasaurs, a group of giant marine reptiles that became extinct at the boundary.

Omnivores, insectivores and carrion-eaters survived the extinction event, perhaps because of the increased availability of their food sources. At the end of the Cretaceous there seem to have been no purely herbivorous or carnivorous mammals. Mammals and birds which survived the extinction fed on insects, larvae, worms, and snails, which in turn fed on dead plant and animal matter. Scientists theorise that these organisms survived the collapse of plant-based food chains because they fed on detritus.

In stream communities, few groups of animals became extinct. Stream communities rely less on food from living plants and more on detritus that washes in from land. This particular ecological niche buffered them from extinction. Similar, but more complex patterns have been found in the oceans. Extinction was more severe among animals living in the water column, than among animals living on or in the sea floor. Animals in the water column are almost entirely dependent on primary production from living phytoplankton, while animals living on or in the ocean floor feed on detritus or can switch to detritus feeding.

The largest air-breathing survivors of the event, crocodilians and champsosaurs, were semi-aquatic and had access to detritus. Modern crocodilians can live as scavengers and can survive for months without food and go into hibernation when conditions are unfavourable, and their young are small, grow slowly, and feed largely on invertebrates and dead organisms or fragments of organisms for their first few years. These characteristics have been linked to crocodilian survival at the end of the Cretaceous.

• Numerous borings in a Cretaceous cobble, Faringdon, England; these are excellent examples of fossil bioerosion.

• Cretaceous hardground from Texas with encrusting oysters and borings. The scale bar is 10 mm.

• Rudist bivalves from the Cretaceous of the Omani Mountains, United Arab Emirates. Scale bar is 10 mm.

• Inoceramus from the Cretaceous of South Dakota.

See also

• Chalk Formation
• List of fossil sites (with link directory)
• South Polar dinosaurs
• Western Interior Seaway
• Cretaceous Thermal Maximum

Notes

References

• Kashiyama, Yuichiro; Nanako O. Ogawa, Junichiro Kuroda, Motoo Shiro, Shinya Nomoto, Ryuji Tada, Hiroshi Kitazato, Naohiko Ohkouchi (2008-05). "Diazotrophic cyanobacteria as the major photoautotrophs during mid-Cretaceous oceanic anoxic events: Nitrogen and carbon isotopic evidence from sedimentary porphyrin". Organic Geochemistry 39 (5): 532–549. doi:10.1016/j.orggeochem.2007.11.010. http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6V7P-4R98K6R-1&_user=1080547&_rdoc=1&_fmt=&_orig=search&_sort=d&view=c&_acct=C000051389&_version=1&_urlVersion=0&_userid=1080547&md5=49204479929f0c87061bf3c69d7b1949. Retrieved 2008-05-10. 
• Neal L Larson, Steven D Jorgensen, Robert A Farrar and Peter L Larson. Ammonites and the other Cephalopods of the Pierre Seaway. Geoscience Press, 1997.
• Ogg, Jim; June, 2004, Overview of Global Boundary Stratotype Sections and Points (GSSP's) http://www.stratigraphy.org/gssp.htm Accessed April 30, 2006.
• Ovechkina, M.N. and Alekseev, A.S. 2005. Quantitative changes of calcareous nannoflora in the Saratov region (Russian Platform) during the late Maastrichtian warming event. Journal of Iberian Geology 31 (1): 149–165. PDF
• Rasnitsyn, A.P. and Quicke, D.L.J. (2002). History of Insects. Kluwer Academic Publishers. ISBN 1-4020-0026-X. —detailed coverage of various aspects of the evolutionary history of the insects.
• Skinner, Brian J., and Stephen C. Porter. The Dynamic Earth: An Introduction to Physical Geology. 3rd ed. New York: John Wiley & Sons, Inc., 1995. ISBN 0-471-60618-9
• Stanley, Steven M. Earth System History. New York: W.H. Freeman and Company, 1999. ISBN 0-7167-2882-6
• Taylor, P.D. and Wilson, M.A., 2003. Palaeoecology and evolution of marine hard substrate communities. Earth-Science Reviews 62: 1–103.[1]

External links

• UCMP Berkeley Cretaceous page
• Bioerosion website at The College of Wooster
• Cretaceous Microfossils: 180+ images of Foraminifera

Cretaceous Period
Lower/Early Cretaceous	Upper/Late Cretaceous
Berriasian | Valanginian | Hauterivian Barremian | Aptian | Albian	Cenomanian | Turonian | Coniacian Santonian | Campanian | Maastrichtian

Preceded by Proterozoic Eon	542 Ma - Phanerozoic Eon - Present
	542 Ma - Paleozoic Era - 251 Ma						251 Ma - Mesozoic Era - 65 Ma			65 Ma - Cenozoic Era - Present
	Cambrian	Ordovician	Silurian	Devonian	Carboniferous	Permian	Triassic	Jurassic	Cretaceous	Paleogene	Neogene	Quaternary

English Journal

• Diatom microfossils from cretaceous and eocene sediments contain native silica precipitating long-chain polyamines.

• Bridoux MC, Ingalls AE.SourceSchool of Oceanography, University of Washington, Seattle, WA, USA.
• Geobiology.Geobiology.2013 May;11(3):215-23. doi: 10.1111/gbi.12028. Epub 2013 Feb 19.
• Organic molecules from known biological sources (biomarkers) that are preserved over geological time are critical tools in the study of past conditions and events on earth. Polar molecules are typically recycled rapidly in marine environments and do not survive burial within aquatic sediments in una
• PMID 23418943

• Embryology of Early Jurassic dinosaur from China with evidence of preserved organic remains.

• Reisz RR, Huang TD, Roberts EM, Peng S, Sullivan C, Stein K, LeBlanc AR, Shieh D, Chang R, Chiang C, Yang C, Zhong S.SourceDepartment of Biology, University of Toronto Mississauga, Mississauga, Ontario L5L 1C6, Canada. robert.reisz@utoronto.ca
• Nature.Nature.2013 Apr 11;496(7444):210-4. doi: 10.1038/nature11978.
• Fossil dinosaur embryos are surprisingly rare, being almost entirely restricted to Upper Cretaceous strata that record the late stages of non-avian dinosaur evolution. Notable exceptions are the oldest known embryos from the Early Jurassic South African sauropodomorph Massospondylus and Late Jurassi
• PMID 23579680

• Early Cretaceous chalks from the North Sea giving evidence for global change.

• Mutterlose J, Bottini C.SourceInstitute for Geology, Mineralogy and Geophysics, Ruhr-University Bochum, Universitätsstr. 150, 44801 Bochum, Germany.
• Nature communications.Nat Commun.2013 Apr 9;4:1686. doi: 10.1038/ncomms2698.
• Among calcareous nannofossils, important primary producers in Jurassic and Cretaceous oceans, nannoconids were carbonate rock-forming organisms. During the late Barremian and early Aptian (~126 to 122 million years ago), nannoconids went through a crisis culminating during the Oceanic Anoxic Event 1
• PMID 23575690

• Feeding height stratification among the herbivorous dinosaurs from the Dinosaur Park Formation (upper Campanian) of Alberta, Canada.

• Mallon JC, Evans DC, Ryan MJ, Anderson JS.AbstractBACKGROUND: Herbivore coexistence on the Late Cretaceous island continent of Laramidia has been a topic of great interest, stemming from the paradoxically high diversity and biomass of these animals in relation to the relatively small landmass available to them. Various hypotheses have been advanced to account for these facts, of which niche partitioning is among the most frequently invoked. However, despite its wide acceptance, this hypothesis has not been rigorously tested. This study uses the fossil assemblage from the Dinosaur Park Formation of Alberta as a model to investigate whether niche partitioning facilitated herbivorous dinosaur coexistence on Laramidia. Specifically, the question of feeding height stratification is examined in light of the role it plays in facilitating modern ungulate coexistence.
• BMC ecology.BMC Ecol.2013 Apr 4;13(1):14. [Epub ahead of print]
• BACKGROUND: Herbivore coexistence on the Late Cretaceous island continent of Laramidia has been a topic of great interest, stemming from the paradoxically high diversity and biomass of these animals in relation to the relatively small landmass available to them. Various hypotheses have been advanced
• PMID 23557203

Japanese Journal

• Carbon isotope stratigraphy and depositional oxia through Cenomanian/Turonian boundary sequences (Upper Cretaceous) in New Zealand

• Hasegawa Takashi,Crampton James,Schiøler Poul,Field Brad,Fukushi Keisuke,Kakizaki Yoshihiro
• Cretaceous
• … Lithological evidence for Cretaceous Oceanic Anoxic Event 2 (OAE2), which preceded and spanned the C/T boundary, is lacking in these sections. …
• NAID 120004442390

• 大分県秩父帯(小坂亜帯)白亜系の衝上ナップ

• 田中 均,高橋 努,内田 暁雄,三宅 由洋,島田 駿祐,赤星 征典,福本 祥大
• 熊本大学教育学部紀要. 自然科学 61, 29-38, 2012-12-12
• NAID 110009526317

• 山口県後期白亜紀防府バソリスの三次元形態 : 地質・岩石と重力異常からの推定

• 今岡 照喜,小室 裕明,山脇 恵理香
• 地質学雑誌 118(12), 782-800, 2012-12
• NAID 40019543194

• 北海道北西部羽幌川支流右ノ沢地域における上部白亜系大型化石層序の再検討

• 河部 壮一郎,岡本 隆
• 地質学雑誌 118(12), 769-781, 2012-12
• NAID 40019543183

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Cretaceous period、Cretaceous

「Cretaceous period」

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Cretaceous