The Mesozoic Era is one of three geologic eras of the Phanerozoic eon. The geologic time scale is a chronologic schema (or idealized Model) relating Stratigraphy to time that is used by Geologists and other The Phanerozoic (occasionally Phanaerozoic) Eon is the current eon in the Geologic timescale, and the one during which abundant animal life has existed The division of time into eras dates back to Giovanni Arduino, in the 18th century, although his original name for the era now called the 'Mesozoic' was 'Secondary' (making the modern era the 'Tertiary'). Giovanni Arduino is the name of Giovanni Arduino (geologist (1714–1795 known as the “father of Italian Geology” Giovanni Arduino (author The chuprichondira 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 Lying between the Paleozoic and the Cenozoic, Mesozoic means 'middle animals', derived from Greek prefix meso-/μεσο- for 'between' and zoon/ζωον meaning animal or 'living being'. The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life" The Cenozoic (also Caenozoic or Cainozoic) Era (ˌsiːnəˈzoʊɪk/ /ˌsɛn- (meaning "new life" ( Greek ( kainos) "new" The Ancient Greek language is the historical stage in the development of the Hellenic language family spanning the Archaic (c It is often called the 'Age of the Dinosaurs', after the dominant fauna of the era. Fauna is all of the Animal life of any particular region or time
The Mesozoic was a time of tectonic, climatic and evolutionary activity. Plate tectonics (from Greek τέκτων tektōn "builder" or "mason" describes the large scale motions of Earth 's Lithosphere Climate encompasses the temperatures humidity rainfall atmospheric particle count and numerous other meteorogical factors in a given region over long periods of eVolution is the third Album by eLDee, it was due to be released in 2008 The continents gradually shifted from a state of connectedness into their present configuration; the drifting provided for speciation and other important evolutionary developments. Speciation is the Evolutionary process by which new biological Species arise The climate was exceptionally warm throughout the period, also playing an important role in the evolution and diversification of new animal species. By the end of the era, the basis of modern life was in place.
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Geologic periods
Following the Paleozoic, the Mesozoic extended roughly 180 million years: from 251 million years ago (Mya) to when the Cenozoic era began 65 Mya. In Astronomy, Geology, and Paleontology, mya or " mya " is an abbreviation for "million years ago". This time frame is separated into three geologic periods. From oldest to youngest:
- Triassic (251. The Triassic is a geologic period and system that extends from about 251 to 199 Ma (million years ago 0 Mya to 199. 6 Mya)
- Jurassic (199. The Jurassic is a geologic period and system that extends from about Ma (million years ago to Ma that is from the end of the Triassic to the beginning 6 Mya to 145. 5 Mya)
- Cretaceous (145. The Cretaceous (kriːˈteɪʃəs, usually abbreviated 'K' for its German translation "Kreide" is a geologic period and system, reaching from the end of 5 Mya to 65. 5 Mya)
The lower (Triassic) boundary is set by the Permian-Triassic extinction event, during which approximately 90% to 96% of marine species and 70% of terrestrial vertebrates became extinct. The Permian–Triassic (P–Tr extinction event, informally known as the Great Dying, was an Extinction event that occurred, and 70 percent of terrestrial In Biology and Ecology, extinction is the cessation of existence of a Species or group of taxa. It is also known as the "Great Dying" because it is considered the largest mass extinction in history. The upper (Cretaceous) boundary is set at the Cretaceous-Tertiary (KT) extinction event, which may have been caused by the impactor that created Chicxulub Crater on the Yucatán Peninsula. The Cretaceous–Tertiary extinction event, which occurred approximately ( Ma) was a large-scale mass extinction of animal and plant species in a geologically The Chicxulub Crater (tʃikʃuˈlub is an ancient Impact crater buried underneath the Yucatán Peninsula in Mexico. The Yucatán Peninsula, in Southeastern Mexico, separates the Caribbean Sea from the Gulf of Mexico. Approximately 50% of all genera became extinct, including all of the non-avian dinosaurs. Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs.
Tectonics
Compared to the vigorous convergent plate mountain-building of the late Paleozoic, Mesozoic tectonic deformation was comparatively mild. Orogeny (Greek for "mountain generating" is the process of natural Mountain building and may be studied as a tectonic structural event as a geographical event and Nevertheless, the era featured the dramatic rifting of the supercontinent Pangaea. In Geology, a supercontinent is a Landmass comprising more than one Continental core or Craton. Pangaea, Pangæa or Pangea (pænˈdʒiːə from παν pan, meaning entire, and Γαῖα Gaea, meaning Earth in Pangaea gradually split into a northern continent, Laurasia, and a southern continent, Gondwana. Laurasia (lɔˈreɪʃiə lɔˈreɪʒə was a Supercontinent that most recently existed as a part of the split of the Pangaean supercontinent in the late Mesozoic Gondwana (ɡɒnˈdwɑːnə originally Gondwanaland) was a southern Supercontinent that existed about 500 to 200 Ma ago This created the passive continental margin that characterizes most of the Atlantic coastline (such as along the U.S. East Coast) today. The continental margin is the zone of the Ocean floor that separates the thin Oceanic crust from thick Continental crust. The East Coast of the United States, also known as the "Eastern Seaboard" or "Atlantic Seaboard" refers to the easternmost coastal states in the central and northern [1]
By the end of the era, the continents had rifted into nearly their present form. Laurasia became North America and Eurasia, while Gondwana split into South America, Africa, Australia, Antarctica and the Indian subcontinent, which collided with the Asian plate during the Cenozoic, the impact giving rise to the Himalayas. For the superstate in George Orwell 's novel see Nations of Nineteen Eighty-Four. South America is a Continent of the Americas, situated entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a For a topic outline on this subject see List of basic Australia topics.
Climate
The Triassic was generally dry, a trend that began in the late Carboniferous, and highly seasonal, especially in the interior of Pangaea. The Carboniferous is a geologic period and system that extends from the end of the Devonian period about 359 Low sea levels may have also exacerbated temperature extremes. With its high specific heat capacity, water acts as a temperature-stabilizing heat, and land areas near large bodies of water—especially the oceans—experience less variation in temperature. Specific heat capacity, also known simply as specific heat, is the measure of the heat energy required to increase the Temperature of a unit quantity Water is a common Chemical substance that is essential for the survival of all known forms of Life. An ocean (from Greek, ''Okeanos'' (Oceanus) is a major body of saline water, and a principal component of the Hydrosphere. Because much of the land that constituted Pangaea was distant from the oceans, temperatures fluctuated greatly, and the interior of Pangaea probably included expansive areas of desert. A desert is a Landscape or region that receives very little precipitation. Abundant evidence of red beds and evaporites such as salt support these conclusions. The term red beds usually refers to strata of reddish -colored sedimentary rocks such as Sandstone, Siltstone or Shale that Salt is a Dietary mineral composed primarily of Sodium chloride that is essential for Animal life but toxic to most land plants
Sea levels began to rise during the Jurassic, which was probably caused by an increase in seafloor spreading. Seafloor spreading occurs at Mid-ocean ridges where new Oceanic crust is formed through volcanic activity and then gradually moves away from the ridge The formation of new crust beneath the surface displaced ocean waters by as much as 200 m more than today, which flooded coastal areas. Furthermore, Pangaea began to rift into smaller divisions, bringing more land area in contact with the ocean by forming the Tethys Sea. The Tethys Ocean was a Mesozoic era Ocean that existed between the continents of Gondwana and Laurasia before the opening of the Indian Temperatures continued to increase and began to stabilize. Humidity also increased with the proximity of water, and deserts retreated. Humidity is the amount of water vapor in the air In daily language the term "humidity" is normally taken to mean Relative humidity.
The climate of the Cretaceous is less certain and more widely disputed. Higher levels of carbon dioxide in the atmosphere are thought to have caused the world temperature gradient from north to south to become almost flat: temperatures were about the same across the planet. Carbon dioxide ( Chemical formula:) is a Chemical compound composed of two Oxygen Atoms covalently bonded to a single Temperature and layers The temperature of the Earth's atmosphere varies with altitude the mathematical relationship between temperature and altitude varies among five In atmospheric sciences ( Meteorology, Climatology and related fields the temperature gradient (typically of air, more generally of any Fluid Average temperatures were also higher than today by about 10 °C. The Celsius Temperature scale was previously known as the centigrade scale. In fact, by the middle Cretaceous, equatorial ocean waters (perhaps as warm as 20 °C in the deep ocean) may have been too warm for sea life, and land areas near the equator may have been deserts despite their proximity to water. The circulation of oxygen to the deep ocean may also have been disrupted. Oxygen (from the Greek roots ὀξύς (oxys (acid literally "sharp" from the taste of acids and -γενής (-genēs (producer literally begetteris the For this reason, large volumes of organic matter accumulated because they were unable to decompose and were eventually deposited as "black shale". Decomposition (or spoilage) refers to the break down of tissue of a formerly living Organism into simpler forms of matter
Not all of the data support these hypotheses, however. Even with the overall warmth, temperature fluctuations should have been sufficient for the presence of polar ice caps and glaciers, but there is no evidence of either. A polar ice cap is a high- Latitude region of a Planet or moon that is covered in Ice. "Glacial" and "Glaciation" redirect here For the geological periods see Glacial period. Quantitative models have also been unable to recreate the flatness of the Cretaceous temperature gradient.
Life
The extinction of nearly all animal species at the end of the Permian period allowed for the radiation of many new lifeforms. The Permian is a geologic period and system that extends from 299 An adaptive radiation is a rapid Evolutionary radiation characterized by an increase in the morphological and ecological diversity of a single rapidly diversifying lineage In particular, the extinction of the large herbivorous and carnivorous dinocephalia left those ecological niches empty. Herbivory is a form of Predation in which an Organism, known as a herbivore, consumes principally Autotrophs ref name=Campbell>Campbell A carnivore (ˈkɑrnɪvɔər meaning 'meat eater' ( Latin carne meaning 'flesh' and vorare meaning 'to devour' is any animal with a diet consisting Dinocephalia are a clade of large early therapsids that flourished during the Middle Permian In Ecology, a niche (pronounced nich nēsh or nish A shorthand definition of niche is how an organism makes a living Some were filled by the surviving cynodonts and dicynodonts, the latter of which subsequently became extinct. Cynodonts, or 'dog teeth' are a taxon of Therapsids which includes modern mammals and their extinct close relatives The Dicynodontia are a Taxon of Therapsids or Mammal-like reptiles. Animal life during the Mesozoic was dominated, however, by large archosaurian reptiles that appeared a few million years after the Permian extinction: dinosaurs, pterosaurs, and aquatic reptiles such as ichthyosaurs, plesiosaurs, and mosasaurs. Archosaurs ( Greek for 'ruling lizards' are a group of Diapsid Reptiles represented by Modern birds and Crocodilians This group also Reptiles, or members of the class Reptilia are air-breathing Cold-blooded Vertebrates that have skin covered in scales as opposed to hair or feathers For other meanings see Pterodactyl (disambiguation. Pterosaurs (ˈtɛrəsɔr from the Greek πτερόσαυρος pterosauros Ichthyosaurs ( Greek for 'fish lizard' - ιχθυς / ichthyos meaning 'fish' and σαυρος / sauros meaning 'lizard' were giant Plesiosaurs (ˈpliːziəˌsɔɹ ( Greek: plesios/πλησιος meaning 'near' or 'close to' and sauros/σαυρος meaning Mosasaurs (from Latin Mosa meaning the ' Meuse river ' in the Netherlands and Greek sauros meaning 'lizard' were serpentine marine
The climatic changes of the late Jurassic and Cretaceous provided for further adaptive radiation. The Jurassic was the height of archosaur diversity, and the first birds and placental mammals also appeared. Birds ( class Aves) are bipedal endothermic ( Warm-blooded) Vertebrate animals that lay eggs. See also Evolution of mammals Eutheria ("true beast" are a group of Mammals consisting of Placental mammals plus all extinct Mammals Angiosperms radiated sometime in the early Cretaceous, first in the tropics, but the even temperature gradient allowed them to spread toward the poles throughout the period. The flowering plants or angiosperms ( Angiospermae or Magnoliophyta) are the most widespread group The Tropics are centered on the Equator and limited in Latitude by the Tropic of Cancer in the northern hemisphere at approximately 23°26' (23 By the end of the Cretaceous, angiosperms dominated tree floras in many areas, although some evidence suggests that biomass was still dominated by cycad and ferns until after the KT extinction. Biomass refers to living and recently dead Biological material that can be used as fuel or for industrial production Cycads are a group of Seed plants characterized by a large crown of compound leaves and a stout trunk. A fern is any one of a group of about 20000 Species of Plants classified in the phylum or division Pteridophyta, also known as Filicophyta
Some have argued that insects diversified with angiosperms because insect anatomy, especially the mouth parts, seems particularly well-suited for flowering plants. Insects ( Class Insecta) are a major group of Arthropods and the most diverse group of Animals on the Earth with over a million described Anatomy (from the Greek anatomia, from ana separate apart from and temnein, to cut up cut open is a branch of Biology that is the consideration The mouth, buccal cavity, or oral cavity is the first portion of the Alimentary canal that receives food and begins digestion by mechanically breaking up However, all major insect mouth parts preceded angiosperms and insect diversification actually slowed when they arrived, so their anatomy originally must have been suited for some other purpose.
As the temperatures in the seas increased, the larger animals of the early Mesozoic gradually began to disappear while smaller animals of all kinds, including lizards, snakes, and perhaps the ancestor mammals to primates, evolved. Lizards are a large and widespread group of Reptiles of the order Squamata, with nearly 5000 species and ranging across all continents except A snake is an elongate Reptile of the suborder Serpentes Like all reptiles snakes are covered in scales. Mammals ( class Mammalia) are a class of Vertebrate Animals characterized by the presence of Sweat glands, including sweat glands A primate is a member of the biological order Primates ( Latin: "prime first rank" the group that contains Lemurs the Aye-aye The KT extinction exacerbated this trend. The large archosaurs became extinct, while birds and mammals thrived, as they do today.
References
- British Mesozoic Fossils, 1983, The Natural History Museum, London.
- ^ Stanley, Steven M. Earth System History. New York: W. H. Freeman and Company, 1999. ISBN 0-7167-2882-6
External links
- The Mesozoic from Palaeos
- The Mesozoic, age of cycads and dinosaurs
- Mesozoic terrestrial ecosystems
- Mesozoic climates
- Paleozoic/Mesozoic climate
| Phanerozoic eon | ||
|---|---|---|
| Paleozoic era | Mesozoic era | Cenozoic era |
| Mesozoic era | ||
|---|---|---|
| Triassic | Jurassic | Cretaceous |
Dictionary
Mesozoic
-adjective
- (geology) Of a geologic era within the Phanerozoic eon and comprises the Triassic, Jurassic and Cretaceous periods from about 230 to 65 million years ago when life on earth was dominated by reptiles.
-proper noun
- (geology) The Mesozoic era.
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