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Encyclopedia > Cretaceous

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The Cretaceous Period (pronounced /kriːˈteɪʃəs/) is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic Period (i.e. from 145.5 ± 4.0 million years ago {Ma}) to the beginning of the Paleocene epoch of the Tertiary Period (about 65.5 ± 0.3 Ma). The youngest and longest geological period of the Mesozoic, the Cretaceous comprises about 80 million years. The end of the Cretaceous defines the boundary between the Mesozoic and Cenozoic eras. A geologic period is a subdivision of geologic time that divides an era into smaller timeframes. ... The geologic time scale is used by geologists and other scientists to describe the timing and relationships between events that have occurred during the history of the Earth. ... The Jurassic Period is a major unit of the geologic timescale that extends from about 199. ... Mega-annum, usually abbreviated as Ma, is a unit of time equal to one million years. ... Annum is a Latin noun meaning year. ... The Paleocene, early dawn of the recent, is a geologic epoch that lasted from 65. ... A division of geologic time less than a period and greater than an age. ... Tertiary geological time interval covers roughly the time span between the demise of the non-avian dinosaurs and beginning of the most recent Ice Age, approximately 65 million to 1. ... Mesozoic Era is one of three geologic eras of the Phanerozoic eon. ... Mammals are the dominant creatures of Cenozoic. ... A geologic era is a subdivision of geologic time that is a separate classification that divides the Phanerozoic Eon into three parts timeframes. ...


The Cretaceous (from Latin creta meaning 'chalk' [1]) as a separate period was first defined by a Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris Basin[2] 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 continental Europe and the British Isles (including the White Cliffs of Dover). For other uses, see Latins and Latin (disambiguation). ... For other uses, see Chalk (disambiguation). ... Jean Baptiste Julien dOmalius dHalloy (1783-1875), Belgian geologist, was born at Liège, Belgium on February 16, 1783. ... For other uses, see strata (novel) and strata title. ... The Paris Basin is one of the major geological regions of France having developed since the Triassic on a basement formed by the Variscan orogeny. ... Calcium carbonate is a chemical compound, with the chemical formula CaCO3. ... Invertebrate is an English word that describes any animal without a spinal column. ... Coccoliths are individual plates of calcium carbonate formed by coccolithophores (single-celled algae such as Emiliania huxleyi) which are arranged around them in a coccosphere. ... For other uses, see Europe (disambiguation). ... This article explains the archipelago in north-western Europe. ... The white cliffs of Dover The location and extent of the white cliffs of Dover. ...


Dating

As with other older geologic periods, the rock beds that define the Cretaceous are well identified but the exact dates of the period's start and end are uncertain by a few million years. No great extinction or burst of diversity separated the Cretaceous from the Jurassic. However, the end of the period is most 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. This bolide collision is probably responsible for the major, extensively-studied Cretaceous–Tertiary extinction event. For other uses, see Extinction (disambiguation). ... This article is about the chemical element. ... Radar topography reveals the 180 kilometer (112 mile) wide ring of the crater (image courtesy NASA/JPL-Caltech) Chicxulub Crater (IPA: ) (cheek-shoo-LOOB) is an ancient impact crater buried underneath the Yucatán Peninsula, with its center located approximately underneath the town of Chicxulub, Yucatán, Mexico. ... The Yucatán Peninsula separates the Caribbean Sea from the Gulf of Mexico. ... Gulf of Mexico in 3D perspective. ... Meteor redirects here. ... Artists reconstruction of a major impact event. ...


Divisions

The Cretaceous is usually separated into Early and Late Cretaceous Epochs. The faunal stages from youngest to oldest are listed below; time is referred to as early or late, and the corresponding rocks are referred to as lower or upper: The Early Cretaceous (timestratigraphic name) or the Lower Cretaceous (logstratigraphic name), is the earlier of the two major divisions of the Cretaceous period. ... Geography of the US in the Late Cretaceous Period Late Cretaceous (100mya - 65mya) refers to the second half of the Cretaceous Period, named after the famous white chalk cliffs of southern England, which date from this time. ... A division of geologic time less than a period and greater than an age. ... Faunal stages are a subdivision of geologic time used primarily by paleontologists who study fossils rather than by geologists who study rock formations. ...

Upper/Late Cretaceous
Maastrichtian (70.6 ± 0.6 – 65.8 ± 0.3 Ma)
Campanian (83.5 ± 0.7 – 70.6 ± 0.6 Ma)
Santonian (85.8 ± 0.7 – 83.5 ± 0.7 Ma)
Coniacian (89.3 ± 1.0 – 85.8 ± 0.7 Ma)
Turonian (93.5 ± 0.8 – 89.3 ± 1.0 Ma)
Cenomanian (99.6 ± 0.9 – 93.5 ± 0.8 Ma)
 
Lower/Early Cretaceous
Albian (112.0 ± 1.0 – 99.6 ± 0.9 Ma)
Aptian (125.0 ± 1.0 – 112.0 ± 1.0 Ma)
Barremian (130.0 ± 1.5 – 125.0 ± 1.0 Ma)
Hauterivian (136.4 ± 2.0 – 130.0 ± 1.5 Ma)
Valanginian (140.2 ± 3.0 – 136.4 ± 2.0 Ma)
Berriasian (145.5 ± 4.0 – 140.2 ± 3.0 Ma)

The Maastrichtian is the last stage of the Cretaceous period, and therefore of the Mesozoic era. ... Annum is a Latin noun meaning year. ... The Campanian is a stage on the geologic time scale occuring from 83. ... The Santonian is a stage of the Late Cretaceous Epoch. ... The Coniacian is a stage of the Late Cretaceous Epoch. ... The Turonian is a stage of the Late Cretaceous Epoch. ... The Cenomanian (also known as Woodbinian) is the first stage of the Late Cretaceous Epoch. ... Albian (Fr. ... In the geologic timescale, the Aptian is the age of the Lower Cretaceous epoch of the Cretaceous period of the Mesozoic era of the Phanerozoic eon that is comprehended between 125 and 112 million years ago, approximately. ... The Barremian faunal stage was a period of geological time between 117 and 113 million years ago. ... The Hauterivian is a stage of the Early Cretaceous Epoch. ... In the geologic timescale, Valanginian is an age of the Lower Cretaceous epoch of the Cretaceous period of the Mesozoic era of the Phanerozoic eon. ... In the geologic timescale, Berriasian is an age of the Lower Cretaceous epoch of the Cretaceous period of the Mesozoic era of the Phanerozoic eon. ...

Paleogeography

During the Cretaceous, the late Paleozoic - early Mesozoic supercontinent of Pangaea completed its 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. The Paleozoic Era (from the Greek palaio, old and zoion, animals, meaning ancient life) is the earliest of three geologic eras of the Phanerozoic eon. ... In geology, a supercontinent is a land mass comprising more than one continental core, or craton. ... For other uses, see Pangaea (disambiguation). ... Animated, colour-coded map showing the various continents. ... // Orogeny (Greek for mountain generating) is the process of mountain building, and may be studied as a tectonic structural event, as a geographical event and a chronological event, in that orogenic events cause distinctive structural phenomena and related tectonic activity, affect certain regions of rocks and crust and happen within... The American cordillera consists of an essentially continuous sequence of mountain ranges that form the western backbone of both North America and South America. ... The Nevadan Orogeny was a major mountain building event that took place along the western edge of ancient North America between the Mid to Late Jurassic(between about 180 and 146 million years ago). ... The Sevier orogeny was a mountain-building event that affected western North America between aproximately 140 million years ago (Ma), and 50 Ma. ... The Laramide orogeny was a period of mountain building in western North America, which started in the Late Cretaceous, 70 to 80 million years ago, and ended 35 to 55 million years ago. ...

Geography of the US in the Late Cretaceous Period
Geography of the 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.[3] Image File history File links US_cretaceous_general. ... Image File history File links US_cretaceous_general. ... For other uses of Gondwana and Gondwanaland, see Gondwana (disambiguation). ... South America South America is a continent crossed by the equator, with most of its area in the Southern Hemisphere. ... A world map showing the continent of Africa Africa is the worlds second-largest and second most-populous continent, after Asia. ... For considerations of sea level change, in particular rise associated with possible global warming, see sea level rise. ... The Tethys Sea was a shallow inland body of water that existed between Laurasia and Gondwana, the geological ancestor of the modern Black, Caspian and Aral Seas. ... North American redirects here. ... Western Interior Seaway during the mid-Cretaceous, about 100 million years before the present The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves during most of... Coal Example chemical structure of coal Coal is a fossil fuel formed in ecosystems where plant remains were saved by water and mud from oxidization and biodegradation. ... A transgression is a geologic event during which sea level rises relative to the land and the shoreline moves toward higher ground, resulting in coastal flooding. ...


The Cretaceous is justly famous for its chalk; indeed, more chalk formed in the Cretaceous than in any other period in the Phanerozoic.[4] 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.[5] 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. For other uses, see Chalk (disambiguation). ... During the Phanerozoic the biodiversity shows a steady but not monotonic increase from near zero to several thousands of genera. ... Oceanic Ridge Oceanic crust is formed at an oceanic ridge, while the lithosphere is subducted back into the asthenosphere at trenches. ... Coccolithophores are single-celled algae, or phytoplankton, belonging to the haptophytes. ... Ball-and-stick model of the carbonate ion, CO32− For other meanings, see Carbonate (disambiguation) In chemistry, a carbonate is a salt or ester of carbonic acid. ... Two types of sedimentary rock: limey shale overlaid by limestone. ... A geologic formation is a formally named rock stratum or geological unit. ... This article is about the U.S. state. ... The Hell Creek Formation is the division of Upper Cretaceous rocks in North America. ... For other uses, see Europe (disambiguation). ... A weald once meant a dense forest, especially the famous great wood once stretching far beyond the ancient counties of Sussex and Kent, England, where this country of smaller woods is still called the Weald. ... The Yixian Formation is a geological formation in Liaoning, Peoples Republic of China, that stems from the early Cretaceous period. ... The Deccan Traps is a large igneous province located in west-central India and is one of the largest volcanic features on Earth. ...


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[6]. Glaciation was however restricted to alpine glaciers on some high-latitude mountains, though seasonal snow may have existed further south. In the geologic timescale, Berriasian is an age of the Lower Cretaceous epoch of the Cretaceous period of the Mesozoic era of the Phanerozoic eon. ... Austrias longest glacier, the Pasterze, winds its 8 km (5 mile) route at the foot of Austrias highest mountain, the Grossglockner A glacier is a large, long-lasting river of ice that is formed on land and moves in response to gravity. ... This article is about the geographical term. ...


After the end of the Berriasian, however, temperatures increased again, and these conditions were almost constant until the end of the period[7]. This trend was due to intense volcanic activity which produced large quantities of carbon dioxide. The development of a number of mantle plumes across the widening mid-ocean ridges 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.[8] This article is about volcanoes in geology. ... Carbon dioxide (chemical formula: ) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. ... A lava lamp illustrates the basic concept of a mantle plume. ... Oceanic Ridge Oceanic crust is formed at an oceanic ridge, while the lithosphere is subducted back into the asthenosphere at trenches. ... The Tethys Sea was a shallow inland body of water that existed between Laurasia and Gondwana, the geological ancestor of the modern Black, Caspian and Aral Seas. ... A plant fossil is any preserved part of a plant that has long since died. ... For other uses, see Alaska (disambiguation). ... Orders & Suborders Saurischia Sauropodomorpha Theropoda Ornithischia Thyreophora Ornithopoda Marginocephalia Dinosaurs were vertebrate animals that dominated the terrestrial ecosystem for over 160 million years, first appearing approximately 230 million years ago. ... For other uses, see South Pole (disambiguation). ...


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.[9] 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[when?], 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.[10][11] The temperature gradient in a given direction from a given spatial starting point is the rate at which temperature changes relative to distance in that direction from that point. ... World map showing the equator in red In tourist areas, the equator is often marked on the sides of roads The equator marked as it crosses Ilhéu das Rolas, in São Tomé and Príncipe. ... Upwelling is an oceanographic phenomenon that involves wind-driven motion of dense, cooler, and usually nutrient-rich water towards the ocean surface, replacing the warmer, usually nutrient-depleted surface water. ... Animated map exhibiting the worlds oceanic waters. ... Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Oceanic Anoxic Events occur when the Earths oceans become completely depleted of O2 below the surface levels. ...


Life

Plants

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, although other gymnosperm taxa like Bennettitales died out before the end of the period.[citation needed] Classes Magnoliopsida - Dicots Liliopsida - Monocots The flowering plants (also angiosperms or Magnoliophyta) are one of the major groups of modern plants, comprising those that produce seeds in specialized reproductive organs called flowers, where the ovulary or carpel is enclosed. ... The Campanian is a stage on the geologic time scale occuring from 83. ... For other uses, see Western honey bee and Bee (disambiguation). ... Bumblebees and the flowers they pollinate co-evolve so that the flower is dependent on the bee and the bee is dependent on the flower for survival In Biology, Co-evolution is the mutual evolutionary influence between two species that become dependent on each other. ... Species About 800, including: Ficus altissima Ficus americana Ficus aurea Ficus benghalensis- Indian Banyan Ficus benjamina- Weeping Fig Ficus broadwayi Ficus carica- Common Fig Ficus citrifolia Ficus coronata Ficus drupacea Ficus elastica Ficus godeffroyi Ficus grenadensis Ficus hartii Ficus lyrata Ficus macbrideii Ficus macrophylla- Moreton Bay Fig Ficus microcarpa- Chinese... Species See text. ... This article is about the plant. ... Divisions Pinophyta (or Coniferophyta) - Conifers Ginkgophyta - Ginkgo Cycadophyta - Cycads Gnetophyta - Gnetum, Ephedra, Welwitschia The gymnosperms (Gymnospermae) are a group of spermatophyte seed-bearing plants with ovules on the edge or blade of an open sporophyll, the sporophylls usually arranged in cone-like structures. ... Orders & Families Cordaitales † Pinales   Pinaceae - Pine family   Araucariaceae - Araucaria family   Podocarpaceae - Yellow-wood family   Sciadopityaceae - Umbrella-pine family   Cupressaceae - Cypress family   Cephalotaxaceae - Plum-yew family   Taxaceae - Yew family Vojnovskyales † Voltziales † The conifers, division Pinophyta, are one of 13 or 14 division level taxa within the Kingdom Plantae. ... Species See text. ... Orders & Families Cordaitales † Pinales   Pinaceae - Pine family   Araucariaceae - Araucaria family   Podocarpaceae - Yellow-wood family   Sciadopityaceae - Umbrella-pine family   Cupressaceae - Cypress family   Cephalotaxaceae - Plum-yew family   Taxaceae - Yew family Vojnovskyales † Voltziales † The conifers, division Pinophyta, are one of 13 or 14 division level taxa within the Kingdom Plantae. ... Bennettitales is an order of plants in the anthophyte clade that first appeared in the Triassic period and became extinct toward the end of the Cretaceous. ...


Terrestrial fauna

On land, mammals were a small and still relatively minor component of the fauna. The fauna was dominated by archosaurian reptiles, especially dinosaurs, which were at their most diverse. 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 specialised families remained. Suborders Pterodactyloidea Rhamphorhynchoidea * Pterosaurs (, from the Greek πτερόσαυρος, pterosauros, meaning winged lizard, often referred to as pterodactyls, from the Greek πτεροδάκτυλος, pterodaktulos, meaning winged finger ) were flying reptiles of the clade Pterosauria. ... Species Campos & Kellner, 1985 (type) (Wellnhofer, 1985) (Bowerbank vide Seeley, 1865) Unwin , 2000 (Owen, 1859) Unwin , 2000 Anhanguera is a genus of pterodactyloid pterosaur known from the Lower-Cretaceous (Aptian) Santana Formation of Brazil. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including milk producing sweat glands, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... Fauna is a collective term for animal life. ... Clades Crurotarsi Aetosauria Crocodilia (crocodiles) Phytosauria Rauisuchia Ornithodira Aves (birds) Dinosauria Pterosauria Archosaurs (Greek for ruling lizards) are a group of diapsid reptiles that is represented today by birds and crocodiles and which also included the dinosaurs. ... Reptilia redirects here. ... Orders & Suborders Saurischia Sauropodomorpha Theropoda Ornithischia Thyreophora Ornithopoda Marginocephalia Dinosaurs were vertebrate animals that dominated the terrestrial ecosystem for over 160 million years, first appearing approximately 230 million years ago. ... Suborders Pterodactyloidea Rhamphorhynchoidea * Pterosaurs (, from the Greek πτερόσαυρος, pterosauros, meaning winged lizard, often referred to as pterodactyls, from the Greek πτεροδάκτυλος, pterodaktulos, meaning winged finger ) were flying reptiles of the clade Pterosauria. ... Four of the 13 finch species found on the Galápagos Archipelago, and thought to have evolved by an adaptive radiation that diversified their beak shapes to adapt them to different food sources. ... For other uses, see Bird (disambiguation). ... The hierarchy of scientific classification In biological classification, family (Latin: familia, plural familiae) is a rank, or a taxon in that rank. ...


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.   (Simplified Chinese: ; Traditional Chinese: ; pinyin: Liáoníng) is a northeastern province of the Peoples Republic of China. ... Lagerstätten (German; singular Lagerstätte; literally place of storage, resting place) are sedimentary deposits that exhibit extraordinary fossil richness or completeness. ... Coelurosauria is a group of theropod dinosaurs that includes the subgroups Tyrannosauridae, Ornithomimidae, and Maniraptora. ... Maniraptora is a group used in biological classification to cover the birds and the dinosaurs that were related to them. ... Two feathers Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, on birds. ...


During the Cretaceous, insects began to diversify, and the oldest known ants, termites and some lepidopterans, akin to butterflies and moths, appeared. Aphids, grasshoppers, and gall wasps appeared. Orders Subclass Apterygota Archaeognatha (bristletails) Thysanura (silverfish) Subclass Pterygota Infraclass Paleoptera (Probably paraphyletic) Ephemeroptera (mayflies) Odonata (dragonflies and damselflies) Infraclass Neoptera Superorder Exopterygota Grylloblattodea (ice-crawlers) Mantophasmatodea (gladiators) Plecoptera (stoneflies) Embioptera (webspinners) Zoraptera (angel insects) Dermaptera (earwigs) Orthoptera (grasshoppers, etc) Phasmatodea (stick insects) Blattodea (cockroaches) Isoptera (termites) Mantodea (mantids) Psocoptera... For other uses, see Ant (disambiguation). ... Families Mastotermitidae Kalotermitidae Termopsidae Hodotermitidae Rhinotermitidae Serritermitidae Termitidae Termites, sometimes known as white ants, are a group of social insects usually classified at the taxonomic rank of order Isoptera. ... Subdivisions See Taxonomy of Lepidoptera and Lepidopteran diversity. ... For other uses of the term butterfly, see butterfly (disambiguation). ... Lepidopteran on a flower. ... Families There are 10 families: Anoeciidae Aphididae Drepanosiphidae Greenideidae Hormaphididae Lachnidae Mindaridae Pemphigidae Phloeomyzidae Thelaxidae Aphids, also known as greenfly or plant lice, are minute plant-feeding insects. ... For other uses, see Grasshopper (disambiguation). ... Gall wasps (Cynipidae), also called Gallflies, are a family of the order Hymenoptera and are classified with the Apocrita suborder of wasps in the superfamily Cynipoidea. ...


Marine fauna

In the seas, rays, modern sharks and teleosts became common. Marine reptiles included ichthyosaurs in the early and middle of the Cretaceous, plesiosaurs throughout the entire period, and mosasaurs in the Late Cretaceous. Orders Rajiformes - common rays and skates Pristiformes - sawfishes Torpediniformes - electric rays See text for families. ... For other uses, see Shark (disambiguation). ... Superorders Osteoglossomorpha Elopomorpha Clupeomorpha Ostariophysi Protacanthopterygii Sternopterygii Cyclosquamata Scopelomorpha Lampridiomorpha Polymyxiomorpha Paracanthopterygii Polymyxiomorpha Acanthopterygii Teleostei is one of three infraclasses in class Actinopterygii, the ray-finned fishes. ... Families Ichthyosauridae Leptonectidae Mixosauridae Ophthalmosauridae Shastasauridae Stenopterygiidae Teretocnemidae Ichthyosaurs (Greek for fish lizard - ιχθυς meaning fish and σαυρος meaning lizard) were giant marine reptiles that resembled fish and dolphins. ... Families Cimoliasauridae Cryptoclididae Elasmosauridae Plesiosauridae Polycotylidae Plesiosaurs (pronounced ) (Greek: plesios meaning near or close to and sauros meaning lizard) were carnivorous aquatic (mostly marine) reptiles. ... Subfamilies Mosasaurinae Plioplatecarpinae Tylosaurinae Mosasaurs (from Latin Mosa, the Meuse river where the fossils were first discovered + Greek sauros, lizard) were serpentine marine reptiles, more closely related to snakes than to monitor lizards (Lee 1997). ...


Baculites, a genus of straight-shelled form of ammonite, flourished in the seas. 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). Species all extinct Baculites (walking stick rock) is a genus of extinct marine animals in the phylum Mollusca and class Cephalopoda. ... For other uses, see Ammonite (disambiguation). ... Families Hesperornithidae Hesperornithiformes are an extinct and highly specialized order of Cretaceous toothed birds. ... Genera Podiceps Tachybaptus Podilymbus Aechmophorus Poliocephalus Rollandia Grebes are members of the Podicipediformes order, a widely distributed order of freshwater diving birds, some of which visit the sea when migrating and in winter. ... Orders Allogromiida Carterinida Fusulinida - extinct Globigerinida Involutinida - extinct Lagenida Miliolida Robertinida Rotaliida Silicoloculinida Spirillinida Textulariida incertae sedis    Xenophyophorea    Reticulomyxa The Foraminifera, or forams for short, are a large group of amoeboid protists with reticulating pseudopods, fine strands that branch and merge to form a dynamic net. ... Classes Asteroidea Concentricycloidea Crinoidea Echinoidea Holothuroidea Ophiuroidea Echinoderms (Echinodermata) is a phylum of marine animals found in the ocean at all depths. ... A database query syntax error has occurred. ... Orders Centrales Pennales Diatoms (Greek: (dia) = through + (temnein) = to cut, i. ... R-phrases R42 R43 R49 S-phrases S22 S36 S37 S45 S53 Flash point non-flammable Supplementary data page Structure and properties n, εr, etc. ... Calcareous formed from or containing a high proportion of Calcium carbonate. ... The Miocene Epoch is a period of time that extends from about 23. ... Bioerosion describes the erosion of hard ocean substrates by living organisms by a number of mechanisms. ...


Extinction

Main article: Cretaceous–Tertiary 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-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.[12] Artists reconstruction of a major impact event. ... Rainforests are among the most biodiverse ecosystems on earth Biodiversity is the variation of taxonomic life forms within a given ecosystem, biome or for the entire Earth. ... An ecological crisis occurs when the environment of a species or a population changes in a way that destablizes its continued survival. ... The Cretaceous-Tertiary (KT) extinction event, also known as the KT boundary (from German: Kreide-Tertiär-Grenzschicht), was a period of massive extinction of species, about 65. ... Two lichens on a rock, in two different ecological niches In ecology, a niche; (pronounced nich, neesh or nish)[1] is a term describing the relational position of a species or population in its ecosystem[1]. The ecological niche; describes how an organism or population responds to the distribution of...


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.[13] Greek clados = branch) or phylogenetic systematics is a branch of biology that determines the evolutionary relationships of living things based on derived similarities. ... Photosynthesis splits water to liberate O2 and fixes CO2 into sugar The leaf is the primary site of photosynthesis in plants. ... Ultraviolet image of the Sun. ... Diagrams of some typical phytoplankton Phytoplankton are the autotrophic component of plankton. ... For other uses, see Plant (disambiguation). ... Food chains, food webs and/or food networks describe the feeding relationships between species to another within an ecosystem. ... In zoology, an herbivore is an animal that is adapted to eat primarily plants (rather than meat). ... This snapping turtle is trying to make a meal of a Canada goose, but the goose is too wary. ... Species T. rex (type) Osborn, 1905 Synonyms Manospondylus Cope, 1892 Dynamosaurus Osborn, 1905  ?Nanotyrannus Bakker, Williams & Currie, 1988 Stygivenator Olshevsky, 1995 Dinotyrannus Olshevsky, 1995 Tyrannosaurus (pronounced IPA: , meaning tyrant lizard) is a genus of theropod dinosaur. ...


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.[14] Coccolithophores (also called coccolithophorids) are single-celled algae, protists and phytoplankton belonging to the class haptophytes. ... Classes Caudofoveata Aplacophora Polyplacophora - Chitons Monoplacophora Bivalvia - Bivalves Scaphopoda - Tusk shells Gastropoda - Snails and Slugs Cephalopoda - Squids, Octopuses, etc. ... For other uses, see Ammonite (disambiguation). ... Rudists are a group of bivalves that peaked in abundance and diversity during the late Mesozoic era, particularly in the Cretaceous period, at the end of which they became extinct. ... For other uses, see Snail (disambiguation). ... Subclasses Pteriomorpha (marine mussels) Palaeoheterodonta (freshwater mussels) Heterodonta (zebra mussels) The common name mussel is used for members of several different families of clams or bivalve molluscs, from both saltwater and freshwater habitats. ... Food chains, food webs and/or food networks describe the feeding relationships between species to another within an ecosystem. ... Subfamilies Mosasaurinae Plioplatecarpinae Tylosaurinae Mosasaurs (from Latin Mosa, the Meuse river where the fossils were first discovered + Greek sauros, lizard) were serpentine marine reptiles, more closely related to snakes than to monitor lizards (Lee 1997). ...


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.[15][12][16] Omnivores are organisms that consume both plants and animals. ... Any organism with a diet that consists chiefly of insects and similar small creatures is an insectivore. ... An American Black Vulture feeding on squirrel carrion For other uses, see Carrion (disambiguation). ... Carnivorism redirects here. ... Subclasses & Infraclasses Subclass †Allotheria* Subclass Prototheria Subclass Theria Infraclass †Trituberculata Infraclass Metatheria Infraclass Eutheria Mammals (class Mammalia) are warm-blooded, vertebrate animals characterized by the presence of sweat glands, including milk producing sweat glands, and by the presence of: hair, three middle ear bones used in hearing, and a neocortex... Orders Subclass Apterygota Archaeognatha (bristletails) Thysanura (silverfish) Subclass Pterygota Infraclass Paleoptera (Probably paraphyletic) Ephemeroptera (mayflies) Odonata (dragonflies and damselflies) Infraclass Neoptera Superorder Exopterygota Grylloblattodea (ice-crawlers) Mantophasmatodea (gladiators) Plecoptera (stoneflies) Embioptera (webspinners) Zoraptera (angel insects) Dermaptera (earwigs) Orthoptera (grasshoppers, etc) Phasmatodea (stick insects) Blattodea (cockroaches) Isoptera (termites) Mantodea (mantids) Psocoptera... A larval insect A larva (Latin; plural larvae) is a juvenile form of animal with indirect development, undergoing metamorphosis (for example, insects or amphibians). ... For other uses, see Worm (disambiguation). ... In biology, detritus is organic waste material from decomposing dead plants or animals. ...


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.[17] 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.[12] Butchers Creek, Omeo, Victoria A stream, brook, beck, burn or creek, is a body of water with a detectable current, confined within a bed and banks. ... A biocoenosis (alternatively, biocoenose or biocenose), termed by Karl Möbius in 1877, describes all the interacting organisms living together in a specific habitat (or biotope). ... Scale diagram of the layers of the pelagic zone. ... Global oceanic and terrestrial photoautotroph abundance, from September 1997 to August 2000. ... The seabed (also sea floor, seafloor, or ocean floor) is the bottom of the ocean. ...


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 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.[15] Suborders Eusuchia Protosuchia † Mesosuchia † Sebecosuchia † Thalattosuchia † Crocodilia is an order of large reptiles that scientists believe branched off from class Reptilia about 220 million years ago. ... Groups Cteniogenidae Simoedosauridae Champsosauridae Choristodera is an order of semi-aquatic diapsid reptiles which ranged from the Middle Jurassic, or possibly Late Triassic, to upper Eocene, or upper Oligocene. ...

See also

The Chalk Formations of Europe are thick deposits of chalk, a soft porous white limestone, deposited in a marine environment during the upper Cretaceous Period. ... List of fossil sites: // ^ http://www. ... Western Interior Seaway during the mid-Cretaceous, about 100 million years before the present The Western Interior Seaway, also called the Cretaceous Seaway, the Niobraran Sea, and the North American Inland Sea, was a huge inland sea that split the continent of North America into two halves during most of...

References

  • 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]

Alexandr (Alex) Rasnitsyn One of world leading experts in palaeoentomology. ... A Dutch STM publishing company now known as Springer. ...

Notes

  1. ^ (1972) Glossary of Geology, 3rd ed., Washington, D.C.: American Geological Institute, p. 165. 
  2. ^ (1974) Great Soviet Encyclopedia, 3rd ed. (in Russian), Moscow: Sovetskaya Enciklopediya, vol. 16, p. 50. 
  3. ^ Dougal Dixon et al., Atlas of Life on Earth, (New York: Barnes & Noble Books, 2001), p. 215.
  4. ^ Stanley, Steven M. Earth System History. New York: W.H. Freeman and Company, 1999. ISBN 0-7167-2882-6 p. 280
  5. ^ Stanley, pp. 279-81
  6. ^ The Berriasian Age
  7. ^ Ibid.
  8. ^ Stanley, pp. 480-2
  9. ^ Stanley, pp. 481-2
  10. ^ "Warmer than a Hot Tub: Atlantic Ocean Temperatures Much Higher in the Past" PhysOrg.com. Retrieved 12/3/06.
  11. ^ 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 0-471-59549-7. p. 557
  12. ^ a b c MacLeod, N, Rawson, PF, Forey, PL, Banner, FT, Boudagher-Fadel, MK, Bown, PR, Burnett, JA, Chambers, P, Culver, S, Evans, SE, Jeffery, C, Kaminski, MA, Lord, AR, Milner, AC, Milner, AR, Morris, N, Owen, E, Rosen, BR, Smith, AB, Taylor, PD, Urquhart, E & Young, JR (1997). "The Cretaceous–Tertiary biotic transition". Journal of the Geological Society 154 (2): 265–292. 
  13. ^ Wilf, P & Johnson KR (2004). "Land plant extinction at the end of the Cretaceous: a quantitative analysis of the North Dakota megafloral record". Paleobiology 30 (3): 347–368. doi:10.1666/0094-8373(2004)030%3C0347:LPEATE%3E2.0.CO;2. 
  14. ^ Kauffman, E (2004). "Mosasaur Predation on Upper Cretaceous Nautiloids and Ammonites from the United States Pacific Coast". Palaios 19 (1): 96–100. Society for Sedimentary Geology. doi:10.1669/0883-1351(2004)019%3C0096:MPOUCN%3E2.0.CO;2. Retrieved on 2007-06-17. 
  15. ^ a b Shehan, P & Hansen, TA (1986). "Detritus feeding as a buffer to extinction at the end of the Cretaceous". Geology 14 (10): 868–870. Retrieved on 2007-07-04. 
  16. ^ Aberhan, M, Weidemeyer, S, Kieesling, W, Scasso, RA, & Medina, FA (2007). "Faunal evidence for reduced productivity and uncoordinated recovery in Southern Hemisphere Cretaceous-Paleogene boundary sections". Geology 35 (3): 227–230. doi:10.1130/G23197A.1. 
  17. ^ Sheehan, PM & Fastovsky, DE (1992). "Major extinctions of land-dwelling vertebrates at the Cretaceous–Tertiary boundary, eastern Montana". Geology 20 (6): 556–560. Retrieved on 2007-06-22. 

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External links

Look up Cretaceous in
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Cretaceous
Cretaceous period
Lower/Early Cretaceous Upper/Late Cretaceous
Berriasian | Valanginian | Hauterivian
Barremian | Aptian | Albian
Cenomanian | Turonian | Coniacian
Santonian | Campanian | Maastrichtian
Mesozoic era
Triassic Jurassic Cretaceous
Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 151 languages. ... Image File history File links Commons-logo. ... The Early Cretaceous (timestratigraphic name) or the Lower Cretaceous (logstratigraphic name), is the earlier of the two major divisions of the Cretaceous period. ... Geography of the US in the Late Cretaceous Period Late Cretaceous (100mya - 65mya) refers to the second half of the Cretaceous Period, named after the famous white chalk cliffs of southern England, which date from this time. ... In the geologic timescale, Berriasian is an age of the Lower Cretaceous epoch of the Cretaceous period of the Mesozoic era of the Phanerozoic eon. ... In the geologic timescale, Valanginian is an age of the Lower Cretaceous epoch of the Cretaceous period of the Mesozoic era of the Phanerozoic eon. ... The Hauterivian is a stage of the Early Cretaceous Epoch. ... The Barremian faunal stage was a period of geological time between 117 and 113 million years ago. ... In the geologic timescale, the Aptian is the age of the Lower Cretaceous epoch of the Cretaceous period of the Mesozoic era of the Phanerozoic eon that is comprehended between 125 and 112 million years ago, approximately. ... Albian (Fr. ... The Cenomanian (also known as Woodbinian) is the first stage of the Late Cretaceous Epoch. ... The Turonian is a stage of the Late Cretaceous Epoch. ... The Coniacian is a stage of the Late Cretaceous Epoch. ... The Santonian is a stage of the Late Cretaceous Epoch. ... The Campanian is a stage on the geologic time scale occuring from 83. ... The Maastrichtian is the last stage of the Cretaceous period, and therefore of the Mesozoic era. ... Mesozoic Era is one of three geologic eras of the Phanerozoic eon. ... The Triassic is a geologic period that extends from about 251 ± 0. ... The Jurassic Period is a major unit of the geologic timescale that extends from about 199. ...

  Results from FactBites:
 
Cretaceous - Wikipedia, the free encyclopedia (1165 words)
The Cretaceous period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic period, about 146 million years ago (Ma), to the beginning of the Paleocene epoch of the Tertiary period (65.5 Ma).
The Cretaceous (from Latin creta, for chalk) was named for the extensive beds of chalk (calcium carbonate deposited by the shells of marine invertebrates) found in the upper Cretaceous of Great Britain (including the White Cliffs of Dover) and adjacent continental Europe.
Pterosaurs were common in the early and middle Cretaceous, but as the Cretaceous proceeded faced growing competition from the adaptive radiation of birds, and by the end of the period only two highly specialised families remained.
Cretaceous - definition of Cretaceous in Encyclopedia (710 words)
The Cretaceous period is one of the major divisions of the geologic timescale, reaching from the end of the Jurassic period (about 135 mya) to the beginning of the Paleocene epoch of the Tertiary period (65 mya).
The Cretaceous (from Latin creta, for chalk) was named for the extensive beds of chalk (calcium carbonate deposited by the shells of marine invertebrates) found in the upper Cretaceous of Britain and adjacent continental Europe.
Pterosaurs were common in the skies and in marine environments (particularly in the early and middle Cretaceous), although on land they faced competition from the adaptive radiation of birds.
  More results at FactBites »

 
 

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