Conodonts are extinct agnathan chordates resembling eels, classified in the class Conodonta. For many years, they were only from tooth-like microfossils found in isolation. Knowledge about soft tissues remains limited, the animals are called Conodontophora to avoid ambiguity. Conodonts are considered index fossils, fossils used to define and identify geologic periods, the conodonts first appeared during the Cambrian Stage 2. The still unnamed Cambrian Stage 10 can be defined as the first appearance of Eoconodontus notchpeakensis, the upper boundary is defined as the appearance of Iapetognathus fluctivagus which marks the beginning of the Tremadocian and is radiometrically dated as 485.4 ±1.9 million years ago. The Cambrian–Ordovician extinction event occurred approximately 488 million years ago and this early Paleozoic extinction event extirpated many conodonts. The Lau event, about 420 million years ago, a relatively minor mass extinction during the Silurian period, had a impact on conodont populations.
The Kačák Event was a period of significant extinctions, the group most affected was the Ammonoidea, although there were faunal turnovers amongst conodonts and dacryoconarids. The entire class is postulated to have wiped out in the Triassic–Jurassic extinction event. These environmental catastrophes caused the extinction of the conodonts, along with 34% of other marine genera, the 11 known fossil imprints of conodont animals record an eel-like creature with 15, or more rarely,19 elements that form a bilaterally symmetrical array in the head. The organisms range from a centimeter or so to 40 cm in length and it is now widely agreed that conodonts had large eyes, fins with fin rays, chevron-shaped muscles and a notochord. Conodont teeth are the earliest found in the fossil record, the evolution of mineralized tissues has been puzzling for more than a century. It has been hypothesized that the first mechanism of mammalian tissue mineralization began either in the skeleton of conodont or the dermal skeleton of early agnathans.
The element array constituted a feeding apparatus that is different from the jaws of modern animals. They are now termed conodont elements to avoid confusion, the three forms of teeth, i. e. coniform cones, ramiform bars, and pectiniform platforms, probably performed different functions. For many years, conodonts were known only from enigmatic tooth-like microfossils, which occur commonly, but not always in isolation, until the early 1980s, conodont teeth had not been found in association with fossils of the host organism, in a konservat lagerstätte. This is because most of the conodont animal was soft-bodied, thus everything and these microfossils are made of hydroxylapatite. The conodont elements can be extracted from rock using adequate solvents and they are widely used in biostratigraphy
Ammonoids are an extinct group of marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs are more related to living coleoids than they are to shelled nautiloids such as the living Nautilus species. The earliest ammonites appear during the Devonian, and the last species died out during the Cretaceous–Paleogene extinction event, Ammonites are excellent index fossils, and it is often possible to link the rock layer in which a particular species or genus is found to specific geologic time periods. Their fossil shells usually take the form of planispirals, although there were some helically spiraled and nonspiraled forms, the name ammonite, from which the scientific term is derived, was inspired by the spiral shape of their fossilized shells, which somewhat resemble tightly coiled rams horns. Pliny the Elder called fossils of these animals ammonis cornua because the Egyptian god Ammon was typically depicted wearing rams horns, often the name of an ammonite genus ends in -ceras, which is Greek for horn.
The topology of the septa, especially around the rim, results in the various suture patterns found, three major types of suture patterns are found in the Ammonoidea, Goniatitic - numerous undivided lobes and saddles, typically 8 lobes around the conch. This pattern is characteristic of the Paleozoic ammonoids, ceratitic - lobes have subdivided tips, giving them a saw-toothed appearance, and rounded undivided saddles. This suture pattern is characteristic of Triassic ammonoids and appears again in the Cretaceous pseudoceratites, ammonitic - lobes and saddles are much subdivided, subdivisions are usually rounded instead of saw-toothed. Ammonoids of this type are the most important species from a point of view. This suture type is characteristic of Jurassic and Cretaceous ammonoids, the siphuncle in most ammonoids by far is a narrow tubular structure that runs along the outer rim, known as the venter, connecting the chambers of the phragmocone to the body or living chamber. This distinguishes them from living nautiloides and typical Nautilida, the word siphuncle comes from the New Latin siphunculus, meaning little siphon.
Originating from within the bactritoid nautiloids, the ammonoid cephalopods first appeared in the Devonian, while nearly all nautiloids show gently curving sutures, the ammonoid suture line is variably folded, forming saddles and lobes. In subsequent taxonomies, these are regarded as orders within the subclass Ammonoidea. Because ammonites and their relatives are extinct, little is known about their way of life. Their soft body parts are rarely preserved in any detail. Nonetheless, much has been worked out by examining ammonoid shells, synchrotron analysis of an aptychophoran ammonite revealed remains of isopod and mollusc larvae in its buccal cavity, indicating at least this kind of ammonite fed on plankton. They may have avoided predation by squirting ink, much like modern cephalopods, the soft body of the creature occupied the largest segments of the shell at the end of the coil. The smaller earlier segments were walled off and the animal could maintain its buoyancy by filling them with gas, the smaller sections of the coil would have floated above the larger sections
The Atlantic Ocean is the second largest of the worlds oceans with a total area of about 106,460,000 square kilometres. It covers approximately 20 percent of the Earths surface and about 29 percent of its surface area. It separates the Old World from the New World, the Atlantic Ocean occupies an elongated, S-shaped basin extending longitudinally between Eurasia and Africa to the east, and the Americas to the west. The Equatorial Counter Current subdivides it into the North Atlantic Ocean, in contrast, the term Atlantic originally referred specifically to the Atlas Mountains in Morocco and the sea off the Strait of Gibraltar and the North African coast. The Greek word thalassa has been reused by scientists for the huge Panthalassa ocean that surrounded the supercontinent Pangaea hundreds of years ago. The term Aethiopian Ocean, derived from Ancient Ethiopia, was applied to the Southern Atlantic as late as the mid-19th century, many Irish or British people refer to the United States and Canada as across the pond, and vice versa.
The Black Atlantic refers to the role of ocean in shaping black peoples history. Irish migration to the US is meant when the term The Green Atlantic is used, the term Red Atlantic has been used in reference to the Marxian concept of an Atlantic working class, as well as to the Atlantic experience of indigenous Americans. Correspondingly, the extent and number of oceans and seas varies, the Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea, to the east, the boundaries of the ocean proper are Europe, the Strait of Gibraltar and Africa. In the southeast, the Atlantic merges into the Indian Ocean, the 20° East meridian, running south from Cape Agulhas to Antarctica defines its border. In the 1953 definition it extends south to Antarctica, while in maps it is bounded at the 60° parallel by the Southern Ocean, the Atlantic has irregular coasts indented by numerous bays and seas. Including these marginal seas the coast line of the Atlantic measures 111,866 km compared to 135,663 km for the Pacific.
Including its marginal seas, the Atlantic covers an area of 106,460,000 km2 or 23. 5% of the ocean and has a volume of 310,410,900 km3 or 23. 3%. Excluding its marginal seas, the Atlantic covers 81,760,000 km2 and has a volume of 305,811,900 km3, the North Atlantic covers 41,490,000 km2 and the South Atlantic 40,270,000 km2. The average depth is 3,646 m and the maximum depth, the bathymetry of the Atlantic is dominated by a submarine mountain range called the Mid-Atlantic Ridge. It runs from 87°N or 300 km south of the North Pole to the subantarctic Bouvet Island at 42°S, the MAR divides the Atlantic longitudinally into two halves, in each of which a series of basins are delimited by secondary, transverse ridges. The MAR reaches above 2000 m along most of its length, the MAR is a barrier for bottom water, but at these two transform faults deep water currents can pass from one side to the other
Dinosaurs are a diverse group of reptiles of the clade Dinosauria that first appeared during the Triassic. Although the exact origin and timing of the evolution of dinosaurs is the subject of active research and they became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201 million years ago. Their dominance continued through the Jurassic and Cretaceous periods and ended when the Cretaceous–Paleogene extinction event led to the extinction of most dinosaur groups 66 million years ago, until the late 20th century, all groups of dinosaurs were believed to be extinct. As such, birds were the dinosaur lineage to survive the mass extinction event. This article deals primarily with non-avian dinosaurs, Dinosaurs are a varied group of animals from taxonomic and ecological standpoints. Birds, at over 10,000 living species, are the most diverse group of vertebrates besides perciform fish, using fossil evidence, paleontologists have identified over 500 distinct genera and more than 1,000 different species of non-avian dinosaurs.
Dinosaurs are represented on every continent by both extant species and fossil remains, while dinosaurs were ancestrally bipedal, many extinct groups included quadrupedal species, and some were able to shift between these stances. Elaborate display structures such as horns or crests are common to all dinosaur groups, evidence suggests that egg laying and nest building are additional traits shared by all dinosaurs.7 meters and heights of 18 meters and were the largest land animals of all time. Still, the idea that dinosaurs were uniformly gigantic is a misconception based in part on preservation bias, as large. Many dinosaurs were small, for example, was only about 50 cm long. Through the first half of the 20th century, before birds were recognized to be dinosaurs, most of the community believed dinosaurs to have been sluggish. Most research conducted since the 1970s, has indicated that all dinosaurs were active animals with elevated metabolisms and numerous adaptations for social interaction.
The large sizes of some groups, as well as their seemingly monstrous and fantastic nature, have ensured dinosaurs regular appearance in best-selling books and films. Persistent public enthusiasm for the animals has resulted in significant funding for dinosaur science, the term is derived from the Greek words δεινός and σαῦρος. Though the taxonomic name has often interpreted as a reference to dinosaurs teeth, claws. Instead, like many forms of reptile sub-groups, did not exhibit characteristics which were traditionally regarded as reptilian. Under phylogenetic nomenclature, dinosaurs are usually defined as the group consisting of Triceratops, their most recent common ancestor, Birds are now recognized as being the sole surviving lineage of theropod dinosaurs. In traditional taxonomy, birds were considered a class that had evolved from dinosaurs
The Permian is a geologic period and system which spans 46.7 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic Period 252.2 Mya. It is the last period of the Paleozoic Era, the following Triassic Period belongs to the Mesozoic Era, the concept of the Permian was introduced in 1841 by geologist Sir Roderick Murchison, who named it after the city of Perm. The Permian witnessed the diversification of the early amniotes into the groups of the mammals, lepidosaurs. The world at the time was dominated by two known as Pangaea and Siberia, surrounded by a global ocean called Panthalassa. The Carboniferous rainforest collapse left behind vast regions of desert within the continental interior, who could better cope with these drier conditions, rose to dominance in place of their amphibian ancestors. The Permian ended with the Permian–Triassic extinction event, the largest mass extinction in Earths history, in which nearly 90% of marine species and it would take well into the Triassic for life to recover from this catastrophe.
Recovery from the Permian-Triassic extinction event was protracted, on land, the term Permian was introduced into geology in 1841 by Sir R. I. Murchison, president of the Geological Society of London, who identified typical strata in extensive Russian explorations undertaken with Edouard de Verneuil, the region now lies in the Perm Krai of Russia. This could have in part caused the extinctions of marine species at the end of the period by severely reducing shallow coastal areas preferred by many marine organisms. During the Permian, all the Earths major landmasses were collected into a supercontinent known as Pangaea. The Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, a new ocean was growing on its southern end, the Tethys Ocean, an ocean that would dominate much of the Mesozoic Era. Large continental landmass interiors experience climates with extreme variations of heat and cold, deserts seem to have been widespread on Pangaea. Such dry conditions favored gymnosperms, plants with seeds enclosed in a cover, over plants such as ferns that disperse spores in a wetter environment.
The first modern trees appeared in the Permian, the climate in the Permian was quite varied. At the start of the Permian, the Earth was still in an Ice Age, glaciers receded around the mid-Permian period as the climate gradually warmed, drying the continents interiors. In the late Permian period, the drying continued although the temperature cycled between warm and cool cycles, Permian marine deposits are rich in fossil mollusks and brachiopods. By the close of the Permian, trilobites and a host of other groups became extinct. Terrestrial life in the Permian included diverse plants, arthropods, the period saw a massive desert covering the interior of Pangaea
Carl Albert Oppel was a German paleontologist. He was born at Hohenheim in Württemberg, on December 19,1831 and he first went to the University of Tübingen, where he graduated with a Ph. D. in 1853. The results of his work was published in Die Juraformation Englands, Frankreichs and he went to the Palaeontological Museum at Munich in 1858 and became an assistant there. It was in 1860 that he became the Professor of Palaeontology at the University of Munich, then, a year later, he became the director of the Palaeontological Collection. Of his works, it can be said that the most important was Paläontologische Mittheilungen aus dem Museum des Königlichen Bayerischen Staates and he died on 23 December 1865 at the age of 34. The wrinkle ridge Dorsum Oppel on the Moon is named after him, Oppel devoted his life to the study of fossils and the examination of the strata of the Jurassic period deposits. He is considered to have founded the study of stratigraphy and the use of index fossils. He established the Tithonian stage, for strata that occur on the borders of Jurassic and he was awarded the Chair of Paleontology at the University of Munich.
List of geologists Paleontology Helmut Mayr, Albert, Neue Deutsche Biographie,19, Duncker & Humblot, pp. 556–557
The Early Triassic is the first of three epochs of the Triassic Period of the geologic timescale. It spans the time between 252.17 Ma and 247.2 Ma, rocks from this epoch are collectively known as the Lower Triassic, which is a unit in chronostratigraphy. The Early Triassic is the oldest epoch of the Mesozoic Era and is divided into the Induan and Olenekian ages, the Lower Triassic series is coeval with the Scythian stage, which is today not included in the official timescales but can be found in older literature. In Europe, most of the Lower Triassic is composed of Buntsandstein, the Permian-Triassic extinction event spawned the Triassic period. The massive extinctions that ended the Permian period and Paleozoic era caused extreme hardships for the surviving species, many types of corals, molluscs and other invertebrates had completely disappeared. The most common Early Triassic hard-shelled marine invertebrates were bivalves, ammonites, the most common land vertebrate was the small herbivorous synapsid Lystrosaurus.
Early Triassic faunas lacked biodiversity and were relatively homogenous throughout the epoch due to the effects of the extinction, the climate during the Early Triassic epoch was generally arid and dry and deserts were widespread, however the poles possessed a temperate climate. Until recently the existence of an event about 3 million years following the end-Permian extinctions was not recognised. Large and mobile species disappeared from the tropics, and amongst the species such as molluscs only the ones that could cope with the heat survived. On land the tropics were practically devoid of life, active animals only returned to the tropics, and plants recolonised on land when temperatures returned to normal around 247 million years ago. Geologic time scale GeoWhen Database - Early Triassic Palaeos scotese
In the geologic timescale, the Anisian is the lower stage or earliest age of the Middle Triassic series or epoch and lasted from 247.2 million years ago until 242 million years ago. The Anisian age succeeds the Olenekian age and precedes the Ladinian age, the stage and its name were established by Austrian geologists Wilhelm Heinrich Waagen and Carl Diener in 1895. The name comes from Anisus, the Latin name of the river Enns, the original type locality is at Großreifling in the Austrian state of Styria. The base of the Anisian stage is laid at the first appearance of conodont species Chiosella timorensis in the stratigraphic record. Other stratigraphers prefer to use the base of magnetic chronozone MT1n, the global reference profile for the base is at a flank of the mountain Deşli Caira in the Romanian Dobruja. The top of the Anisian is at the first appearance of ammonite species Eoprotrachyceras curionii, the conodont species Neogondolella praehungarica appears at the same level. Especially in Central Europe the Anisian stage is sometimes subdivided into four substages, Bythinian and Illyrian.
Rieber, H. Nicora, A. & Mundil, R.2005, The Global boundary Stratotype Section and Point of the Ladinian Stage at Bagolino and its implications for the Triassic time scale, Episodes 28, pp. 233–244. Grǎdinaru, E. Orchard, M. J. Nicora, A. Gallet, besse, J. Krystyn, L. Sobolev, E. S. & Ivanova, D.2007, The Global Boundary Stratotype Section and Point for the base of the Anisian Stage, Deşli Caira Hill, North Dobrogea, Albertiana 36, pp. 54–71. & Smith, A. G.2004, A Geologic Time Scale 2004, Cambridge University Press
Italy, officially the Italian Republic, is a unitary parliamentary republic in Europe. Located in the heart of the Mediterranean Sea, Italy shares open land borders with France, Austria, San Marino, Italy covers an area of 301,338 km2 and has a largely temperate seasonal climate and Mediterranean climate. Due to its shape, it is referred to in Italy as lo Stivale. With 61 million inhabitants, it is the fourth most populous EU member state, the Italic tribe known as the Latins formed the Roman Kingdom, which eventually became a republic that conquered and assimilated other nearby civilisations. The legacy of the Roman Empire is widespread and can be observed in the distribution of civilian law, republican governments, Christianity. The Renaissance began in Italy and spread to the rest of Europe, bringing a renewed interest in humanism, exploration, Italian culture flourished at this time, producing famous scholars and polymaths such as Leonardo da Vinci, Galileo and Machiavelli. The weakened sovereigns soon fell victim to conquest by European powers such as France and Austria.
Despite being one of the victors in World War I, Italy entered a period of economic crisis and social turmoil. The subsequent participation in World War II on the Axis side ended in defeat, economic destruction. Today, Italy has the third largest economy in the Eurozone and it has a very high level of human development and is ranked sixth in the world for life expectancy. The country plays a prominent role in regional and global economic, military and diplomatic affairs, as a reflection of its cultural wealth, Italy is home to 51 World Heritage Sites, the most in the world, and is the fifth most visited country. The assumptions on the etymology of the name Italia are very numerous, according to one of the more common explanations, the term Italia, from Latin, was borrowed through Greek from the Oscan Víteliú, meaning land of young cattle. The bull was a symbol of the southern Italic tribes and was often depicted goring the Roman wolf as a defiant symbol of free Italy during the Social War. Greek historian Dionysius of Halicarnassus states this account together with the legend that Italy was named after Italus, mentioned by Aristotle and Thucydides.
The name Italia originally applied only to a part of what is now Southern Italy – according to Antiochus of Syracuse, but by his time Oenotria and Italy had become synonymous, and the name applied to most of Lucania as well. The Greeks gradually came to apply the name Italia to a larger region, excavations throughout Italy revealed a Neanderthal presence dating back to the Palaeolithic period, some 200,000 years ago, modern Humans arrived about 40,000 years ago. Other ancient Italian peoples of undetermined language families but of possible origins include the Rhaetian people and Cammuni. Also the Phoenicians established colonies on the coasts of Sardinia and Sicily, the Roman legacy has deeply influenced the Western civilisation, shaping most of the modern world
Psiloceras is an extinct genus of cephalopod belonging to the ammonite subclass. Psiloceras fossils are found at Watchet, England. Here smooth-shelled Psiloceras planorbis are to be found as usually flattened fossils in the Blue Lias, unlike most earlier ammonites, which had complex shell shapes and ornamentation, Psiloceras had a smooth shell. All Ammonites, with the exemption of the genus Psiloceras were wiped out at the Triassic–Jurassic extinction event. Hence all ammonites that lived during the Jurassic and Cretaceous are descendants of Psiloceras, most authors assume that Psiloceras descended from the Phyllocerataceae. P. spelae is probably the earliest species of Psiloceras, Jurassic of Argentina, Canada, France, New Zealand, the United Kingdom, United States
The Triassic is a geologic period and system which spans 50.9 million years from the end of the Permian Period 252.17 million years ago, to the beginning of the Jurassic Period 201.3 Mya. The Triassic is the first period of the Mesozoic Era, both the start and end of the period are marked by major extinction events. Therapsids and archosaurs were the terrestrial vertebrates during this time. A specialized subgroup of archosaurs, called dinosaurs, first appeared in the Late Triassic, the vast supercontinent of Pangaea existed until the mid-Triassic, after which it began to gradually rift into two separate landmasses, Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry, the climate shifted and became more humid as Pangaea began to drift apart. The end of the period was marked by yet another mass extinction, the Triassic-Jurassic extinction event. The Triassic is usually separated into Early and Late Triassic Epochs, from the east, along the equator, the Tethys sea penetrated Pangaea, causing the Paleo-Tethys Ocean to be closed.
Later in the mid-Triassic a similar sea penetrated along the equator from the west, the remaining shores were surrounded by the world-ocean known as Panthalassa. All the deep-ocean sediments laid down during the Triassic have disappeared through subduction of oceanic plates, the supercontinent Pangaea was rifting during the Triassic—especially late in that period—but had not yet separated. In North America, for example, marine deposits are limited to a few exposures in the west, thus Triassic stratigraphy is mostly based on organisms that lived in lagoons and hypersaline environments, such as Estheria crustaceans. At the beginning of the Mesozoic Era, Africa was joined with Earths other continents in Pangaea, Africa shared the supercontinents relatively uniform fauna which was dominated by theropods and primitive ornithischians by the close of the Triassic period. Late Triassic fossils are found throughout Africa, but are common in the south than north. The time boundary separating the Permian and Triassic marks the advent of an event with global impact.
At Paleorrota geopark, located in Rio Grande do Sul, Brazil, in these formations, one of the earliest dinosaurs, Staurikosaurus, as well as the mammal ancestors Brasilitherium and Brasilodon have been discovered. The Triassic continental interior climate was hot and dry, so that typical deposits are red bed sandstones and evaporites. Pangaeas large size limited the effect of the global ocean, its continental climate was highly seasonal, with very hot summers. The strong contrast between the Pangea supercontinent and the global ocean triggered intense cross-equatorial monsoons, the best studied of such episodes of humid climate, and probably the most intense and widespread, was the Carnian Pluvial Event. On land, the vascular plants included the lycophytes, the dominant cycadophytes, ferns, horsetails