Moritz Hörnes, Austrian palaeontologist, was born in Vienna. He was educated at the University of Vienna and graduated with a PhD, he became an assistant in the Vienna mineralogical museum. He was distinguished for his research on the Cenozoic Mollusca of the Vienna Basin and of Alpine regions. Most of his memoirs were published in the Jahrbuch der K. K. geol. Reichsanstalt. In 1864 he introduced the term Neogene to include Miocene and Pliocene, as these formations are not always to be separated: the fauna of the lower division being subtropical and giving place in the upper division to Mediterranean forms, he died in Vienna on 4 November 1868. In 1860 the mineral hörnesite was named in his honor by Wilhelm Haidinger, with Gustav Adolph Kenngott being its co-describer, his son Dr. Rudolf Hörnes, professor of geology and palaeontology in the university of Graz carried on researches among the Cenozoic mollusca, is author of Elemente der Palaeontologie; this article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed..
"Hörnes, Moritz". Encyclopædia Britannica. Cambridge University Press
Birds known as Aves, are a group of endothermic vertebrates, characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, a strong yet lightweight skeleton. Birds range in size from the 5 cm bee hummingbird to the 2.75 m ostrich. They rank as the world's most numerically-successful class of tetrapods, with ten thousand living species, more than half of these being passerines, sometimes known as perching birds. Birds have wings which are less developed depending on the species. Wings, which evolved from forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in flightless birds, including ratites and diverse endemic island species of birds; the digestive and respiratory systems of birds are uniquely adapted for flight. Some bird species of aquatic environments seabirds and some waterbirds, have further evolved for swimming; the fossil record demonstrates that birds are modern feathered dinosaurs, having evolved from earlier feathered dinosaurs within the theropod group, which are traditionally placed within the saurischian dinosaurs.
The closest living relatives of birds are the crocodilians. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period, around 170 million years ago. Many of these early "stem-birds", such as Archaeopteryx, were not yet capable of powered flight, many retained primitive characteristics like toothy jaws in place of beaks, long bony tails. DNA-based evidence finds that birds diversified around the time of the Cretaceous–Palaeogene extinction event 66 million years ago, which killed off the pterosaurs and all the non-avian dinosaur lineages, but birds those in the southern continents, survived this event and migrated to other parts of the world while diversifying during periods of global cooling. This makes them the sole surviving dinosaurs according to cladistics; some birds corvids and parrots, are among the most intelligent animals. Many species annually migrate great distances. Birds are social, communicating with visual signals and bird songs, participating in such social behaviours as cooperative breeding and hunting and mobbing of predators.
The vast majority of bird species are monogamous for one breeding season at a time, sometimes for years, but for life. Other species have breeding systems that are polygynous or polyandrous. Birds produce offspring by laying eggs, they are laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching; some birds, such as hens, lay eggs when not fertilised, though unfertilised eggs do not produce offspring. Many species of birds are economically important as food for human consumption and raw material in manufacturing, with domesticated and undomesticated birds being important sources of eggs and feathers. Songbirds and other species are popular as pets. Guano is harvested for use as a fertiliser. Birds prominently figure throughout human culture. About 120–130 species have become extinct due to human activity since the 17th century, hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them.
Recreational birdwatching is an important part of the ecotourism industry. The first classification of birds was developed by Francis Willughby and John Ray in their 1676 volume Ornithologiae. Carl Linnaeus modified that work in 1758 to devise the taxonomic classification system in use. Birds are categorised as the biological class Aves in Linnaean taxonomy. Phylogenetic taxonomy places Aves in the dinosaur clade Theropoda. Aves and a sister group, the clade Crocodilia, contain the only living representatives of the reptile clade Archosauria. During the late 1990s, Aves was most defined phylogenetically as all descendants of the most recent common ancestor of modern birds and Archaeopteryx lithographica. However, an earlier definition proposed by Jacques Gauthier gained wide currency in the 21st century, is used by many scientists including adherents of the Phylocode system. Gauthier defined Aves to include only the crown group of the set of modern birds; this was done by excluding most groups known only from fossils, assigning them, instead, to the Avialae, in part to avoid the uncertainties about the placement of Archaeopteryx in relation to animals traditionally thought of as theropod dinosaurs.
Gauthier identified four different definitions for the same biological name "Aves", a problem. Gauthier proposed to reserve the term Aves only for the crown group consisting of the last common ancestor of all living birds and all of its descendants, which corresponds to meaning number 4 below, he assigned other names to the other groups. Aves can mean all archosaurs closer to birds than to crocodiles Aves can mean those advanced archosaurs with feathers Aves can mean those feathered dinosaurs that fly Aves can mean the last common ancestor of all the living birds and all of its descendants (a "c
The Arctic Ocean is the smallest and shallowest of the world's five major oceans. The International Hydrographic Organization recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea or the Arctic Sea, classifying it a mediterranean sea or an estuary of the Atlantic Ocean, it is seen as the northernmost part of the all-encompassing World Ocean. Located in the Arctic north polar region in the middle of the Northern Hemisphere, the Arctic Ocean is completely surrounded by Eurasia and North America, it is covered by sea ice throughout the year and completely in winter. The Arctic Ocean's surface temperature and salinity vary seasonally as the ice cover melts and freezes; the summer shrinking of the ice has been quoted at 50%. The US National Snow and Ice Data Center uses satellite data to provide a daily record of Arctic sea ice cover and the rate of melting compared to an average period and specific past years. Human habitation in the North American polar region goes back at least 50,000–17,000 years ago, during the Wisconsin glaciation.
At this time, falling sea levels allowed people to move across the Bering land bridge that joined Siberia to north west North America, leading to the Settlement of the Americas. Paleo-Eskimo groups included the Pre-Dorset; the Dorset were the last major Paleo-Eskimo culture in the Arctic before the migration east from present-day Alaska of the Thule, the ancestors of the modern Inuit. The Thule Tradition lasted from about 200 B. C. to 1600 A. D. around the Bering Strait, the Thule people being the prehistoric ancestors of the Inuit who now live in Northern Labrador. For much of European history, the north polar regions remained unexplored and their geography conjectural. Pytheas of Massilia recorded an account of a journey northward in 325 BC, to a land he called "Eschate Thule", where the Sun only set for three hours each day and the water was replaced by a congealed substance "on which one can neither walk nor sail", he was describing loose sea ice known today as "growlers" or "bergy bits". Early cartographers were unsure whether to draw the region around the North Pole as water.
The fervent desire of European merchants for a northern passage, the Northern Sea Route or the Northwest Passage, to "Cathay" caused water to win out, by 1723 mapmakers such as Johann Homann featured an extensive "Oceanus Septentrionalis" at the northern edge of their charts. The few expeditions to penetrate much beyond the Arctic Circle in this era added only small islands, such as Novaya Zemlya and Spitzbergen, though since these were surrounded by pack-ice, their northern limits were not so clear; the makers of navigational charts, more conservative than some of the more fanciful cartographers, tended to leave the region blank, with only fragments of known coastline sketched in. This lack of knowledge of what lay north of the shifting barrier of ice gave rise to a number of conjectures. In England and other European nations, the myth of an "Open Polar Sea" was persistent. John Barrow, longtime Second Secretary of the British Admiralty, promoted exploration of the region from 1818 to 1845 in search of this.
In the United States in the 1850s and 1860s, the explorers Elisha Kane and Isaac Israel Hayes both claimed to have seen part of this elusive body of water. Quite late in the century, the eminent authority Matthew Fontaine Maury included a description of the Open Polar Sea in his textbook The Physical Geography of the Sea; as all the explorers who travelled closer and closer to the pole reported, the polar ice cap is quite thick, persists year-round. Fridtjof Nansen was the first to make a nautical crossing of the Arctic Ocean, in 1896; the first surface crossing of the ocean was led by Wally Herbert in 1969, in a dog sled expedition from Alaska to Svalbard, with air support. The first nautical transit of the north pole was made in 1958 by the submarine USS Nautilus, the first surface nautical transit occurred in 1977 by the icebreaker NS Arktika. Since 1937, Soviet and Russian manned drifting ice stations have extensively monitored the Arctic Ocean. Scientific settlements were established on the drift ice and carried thousands of kilometers by ice floes.
In World War II, the European region of the Arctic Ocean was contested: the Allied commitment to resupply the Soviet Union via its northern ports was opposed by German naval and air forces. Since 1954 commercial airlines have flown over the Arctic Ocean; the Arctic Ocean occupies a circular basin and covers an area of about 14,056,000 km2 the size of Antarctica. The coastline is 45,390 km long, it is surrounded by the land masses of Eurasia, North America, by several islands. It is taken to include Baffin Bay, Barents Sea, Beaufort Sea, Chukchi Sea, East Siberian Sea, Greenland Sea, Hudson Bay, Hudson Strait, Kara Sea, Laptev Sea, White Sea and other tributary bodies of water
Isthmus of Panama
The Isthmus of Panama historically known as the Isthmus of Darien, is the narrow strip of land that lies between the Caribbean Sea and the Pacific Ocean, linking North and South America. It contains the country of the Panama Canal. Like many isthmuses, it is a location of great strategic value; the isthmus formed around 2.8 million years ago, separating the Atlantic and Pacific Oceans and causing the creation of the Gulf Stream. This was first suggested in 1910 by North American paleontologist Henry Fairfield Osborn, he based the proposal on the fossil record of mammals in Central America. This conclusion provided a foundation for Alfred Wegener when he proposed the theory of continental drift in 1912. Vasco Núñez de Balboa heard of the South Sea from natives while sailing along the Caribbean coast. On 25 September 1513 he saw the Pacific. In 1519 the town of Panamá was founded near a small indigenous settlement on the Pacific coast. After the discovery of Peru, it developed into an important port of trade and became an administrative centre.
In 1671 the Welsh pirate Henry Morgan crossed the Isthmus of Panamá from the Caribbean side and destroyed the city. The town was relocated some kilometers to the west at a small peninsula; the ruins of the old town, Panamá Viejo, are preserved and were declared a UNESCO World Heritage Site in 1997. Silver and gold from the viceroyalty of Peru were transported overland across the isthmus by Spanish Silver Train to Porto Bello, where Spanish treasure fleets shipped them to Seville and Cádiz from 1707. Lionel Wafer spent four years between 1684 among the Cuna Indians. Scotland tried to establish a settlement in 1698 through the Darien scheme; the California Gold Rush, starting in 1849, brought a large increase in the transportation of people from the Atlantic to the Pacific. Steamships brought gold diggers from eastern US ports, who trekked across the isthmus by foot and rail. On the Pacific side, they boarded. Ferdinand de Lesseps, the man behind the Suez Canal, started a Panama Canal Company in 1880 that went bankrupt in 1889 in the Panama scandals.
In 1902–4, the United States forced Colombia to grant independence to the Department of the Isthmus, bought the remaining assets of the Panama Canal Company, finished the canal in 1914. A significant body of water once separated the continents of North and South America, allowing the waters of the Pacific and Atlantic Oceans to mix freely. Beneath the surface, two plates of the Earth's crust were colliding, forcing the Cocos Plate to slide under the Caribbean Plate; the pressure and heat caused by this collision led to the formation of underwater volcanoes, some of which grew large enough to form islands. Meanwhile, movement of the two tectonic plates was pushing up the sea floor forcing some areas above sea level. Over time, massive amounts of sediment from North and South America filled the gaps between the newly forming islands. Over millions of years, the sediment deposits added to the islands until the gap was filled. By no than 4.5 million years ago, an isthmus had formed between North and South America.
However, an article in Science Magazine stated that zircon crystals in middle Miocene bedrock from northern Colombia indicated that by 10 million years ago, it is that instead of islands, a full isthmus between the North and South American continents had likely formed where the Central American Seaway had been previously. Evidence suggests that the creation of this land mass and the subsequent warm, wet weather over northern Europe resulted in the formation of a large Arctic ice cap and contributed to the current ice age; that warm currents can lead to glacier formation may seem counterintuitive, but heated air flowing over the warm Gulf Stream can hold more moisture. The result is increased precipitation; the formation of the Isthmus of Panama played a major role in biodiversity on the planet. The bridge made it easier for plants to migrate between the two continents; this event is known in paleontology as the Great American Interchange. For instance, in North America, the opossum and porcupine all trace back to ancestors that came across the land bridge from South America.
Bears, dogs, horses and raccoons all made the trek south across the isthmus. As the connecting bridge between two vast land masses, the Panamanian biosphere is filled with overlapping fauna and flora from both North and South America. There are, over 978 species of birds in the isthmus area; the tropical climate encourages a myriad of large and brightly colored species, amphibians, birds and reptiles. Divided along its length by a mountain range, the isthmus's weather is wet on the Atlantic side but has a clearer division into wet and dry seasons on the Pacific side. Darien Gap Isthmo-Colombian area Postage stamps and postal history of the Canal Zone
The Ordovician is a geologic period and system, the second of six periods of the Paleozoic Era. The Ordovician spans 41.2 million years from the end of the Cambrian Period 485.4 million years ago to the start of the Silurian Period 443.8 Mya. The Ordovician, named after the Celtic tribe of the Ordovices, was defined by Charles Lapworth in 1879 to resolve a dispute between followers of Adam Sedgwick and Roderick Murchison, who were placing the same rock beds in northern Wales into the Cambrian and Silurian systems, respectively. Lapworth recognized that the fossil fauna in the disputed strata were different from those of either the Cambrian or the Silurian systems, placed them in a system of their own; the Ordovician received international approval in 1960, when it was adopted as an official period of the Paleozoic Era by the International Geological Congress. Life continued to flourish during the Ordovician as it did in the earlier Cambrian period, although the end of the period was marked by the Ordovician–Silurian extinction events.
Invertebrates, namely molluscs and arthropods, dominated the oceans. The Great Ordovician Biodiversification Event increased the diversity of life. Fish, the world's first true vertebrates, continued to evolve, those with jaws may have first appeared late in the period. Life had yet to diversify on land. About 100 times as many meteorites struck the Earth per year during the Ordovician compared with today; the Ordovician Period began with a major extinction called the Cambrian–Ordovician extinction event, about 485.4 Mya. It lasted for about 42 million years and ended with the Ordovician–Silurian extinction events, about 443.8 Mya which wiped out 60% of marine genera. The dates given are recent radiometric dates and vary from those found in other sources; this second period of the Paleozoic era created abundant fossils that became major petroleum and gas reservoirs. The boundary chosen for the beginning of both the Ordovician Period and the Tremadocian stage is significant, it correlates well with the occurrence of widespread graptolite and trilobite species.
The base of the Tremadocian allows scientists to relate these species not only to each other, but to species that occur with them in other areas. This makes it easier to place many more species in time relative to the beginning of the Ordovician Period. A number of regional terms have been used to subdivide the Ordovician Period. In 2008, the ICS erected a formal international system of subdivisions. There exist Baltoscandic, Siberian, North American, Chinese Mediterranean and North-Gondwanan regional stratigraphic schemes; the Ordovician Period in Britain was traditionally broken into Early and Late epochs. The corresponding rocks of the Ordovician System are referred to as coming from the Lower, Middle, or Upper part of the column; the faunal stages from youngest to oldest are: Late Ordovician Hirnantian/Gamach Rawtheyan/Richmond Cautleyan/Richmond Pusgillian/Maysville/Richmond Middle Ordovician Trenton Onnian/Maysville/Eden Actonian/Eden Marshbrookian/Sherman Longvillian/Sherman Soudleyan/Kirkfield Harnagian/Rockland Costonian/Black River Chazy Llandeilo Whiterock Llanvirn Early Ordovician Cassinian Arenig/Jefferson/Castleman Tremadoc/Deming/Gaconadian The Tremadoc corresponds to the Tremadocian.
The Floian corresponds to the lower Arenig. The Llanvirn occupies the rest of the Darriwilian, terminates with it at the base of the Late Ordovician; the Sandbian represents the first half of the Caradoc. During the Ordovician, the southern continents were collected into Gondwana. Gondwana started the period in equatorial latitudes and, as the period progressed, drifted toward the South Pole. Early in the Ordovician, the continents of Laurentia and Baltica were still independent continents, but Baltica began to move towards Laurentia in the period, causing the Iapetus Ocean between them to shrink; the small continent Avalonia separated from Gondwana and began to move north towards Baltica and Laurentia, opening the Rheic Ocean between Gondwana and Avalonia. The Taconic orogeny, a major mountain-building episode, was well under way in Cambrian times. In the early and middle Ordovician, temperatures were mild, but at the beginning of the Late Ordovician, from 460 to 450 Ma, volcanoes along the margin of the Iapetus Ocean spewed massive amounts of carbon dioxide, a greenhouse gas, into the atmosphere, turning the planet into a hothouse.
Sea levels were high, but as Gondwana moved south, ice accumulated into glaciers and sea levels dropped. At first, low-lying sea beds increased diversity, but glaciation led to mass extinctions as the seas drained and continental shelves became dry land. During the Ordovician, in fact during the Tremadocian, marine transgressions worldwide were the greatest for which evidence is preserved; these volcanic island arcs collided with proto North America to form the Appalachian mountains. By the end of the Late Ordovician the volcanic emissions had stopped. Gondwana had by that time neared the South Pole and was glaciated
The Permian is a geologic period and system which spans 47 million years from the end of the Carboniferous Period 298.9 million years ago, to the beginning of the Triassic period 251.902 Mya. It is the last period of the Paleozoic 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 ancestral groups of the mammals, turtles and archosaurs; the world at the time was dominated by two continents 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. Amniotes, 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 Earth's history, in which nearly 96% of marine species and 70% of terrestrial species died out.
It would take well into the Triassic for life to recover from this catastrophe. Recovery from the Permian–Triassic extinction event was protracted; 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 Édouard de Verneuil; the region now lies in the Perm Krai of Russia. Official ICS 2017 subdivisions of the Permian System from most recent to most ancient rock layers are: Lopingian epoch Changhsingian Wuchiapingian Others: Waiitian Makabewan Ochoan Guadalupian epoch Capitanian stage Wordian stage Roadian stage Others: Kazanian or Maokovian Braxtonian stage Cisuralian epoch Kungurian stage Artinskian stage Sakmarian stage Asselian stage Others: Telfordian Mangapirian Sea levels in the Permian remained low, near-shore environments were reduced as all major landmasses collected into a single continent—Pangaea; this could have in part caused the widespread extinctions of marine species at the end of the period by reducing shallow coastal areas preferred by many marine organisms.
During the Permian, all the Earth's major landmasses were collected into a single supercontinent known as Pangaea. Pangaea straddled the equator and extended toward the poles, with a corresponding effect on ocean currents in the single great ocean, the Paleo-Tethys Ocean, a large ocean that existed between Asia and Gondwana; the Cimmeria continent rifted away from Gondwana and drifted north to Laurasia, causing the Paleo-Tethys Ocean to shrink. 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 and monsoon conditions with seasonal rainfall patterns. Deserts seem to have been widespread on Pangaea; such dry conditions favored gymnosperms, plants with seeds enclosed in a protective cover, over plants such as ferns that disperse spores in a wetter environment. The first modern trees appeared in the Permian. Three general areas are noted for their extensive Permian deposits—the Ural Mountains and the southwest of North America, including the Texas red beds.
The Permian Basin in the U. S. states of Texas and New Mexico is so named because it has one of the thickest deposits of Permian rocks in the world. 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 warmed, drying the continent's 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. Fossilized shells of two kinds of invertebrates are used to identify Permian strata and correlate them between sites: fusulinids, a kind of shelled amoeba-like protist, one of the foraminiferans, ammonoids, shelled cephalopods that are distant relatives of the modern nautilus. By the close of the Permian, trilobites and a host of other marine groups became extinct. Terrestrial life in the Permian included diverse plants, fungi and various types of tetrapods; the period saw a massive desert covering the interior of Pangaea.
The warm zone spread in the northern hemisphere. The rocks formed at that time were stained red by iron oxides, the result of intense heating by the sun of a surface devoid of vegetation cover. A number of older types of plants and animals became marginal elements; the Permian began with the Carboniferous flora still flourishing. About the middle of the Permian a major transition in vegetation began; the swamp-loving
The Langhian is, in the ICS geologic timescale, an age or stage in the middle Miocene epoch/series. It spans the time between 13.65 ± 0.05 Ma during the Middle Miocene. The Langhian was a continuing warming period defined by Lorenzo Pareto in 1865, it was established in the Langhe area north of Ceva in northern Italy, hence the name; the Langhian is followed by the Serravallian stage. The base of the Langhian is defined by the first appearance of foraminifer species Praeorbulina glomerosa and is coeval with the top of magnetic chronozone C5Cn.1n. A GSSP for the Langhian stage was not yet established in 2009; the top of the Langhian stage is at the first occurrence of fossils of the nanoplankton species Sphenolithus heteromorphus and is located in magnetic chronozone C5ABr. The Langhian is coeval with the Orleanian and Astaracian European Land Mammal Mega Zones, with the upper Hemingfordian to mid-Barstovian North American Land Mammal Ages, with mid-Relizian to Luisian Californian regional stages, with the early-mid Badenian Paratethys stage of Central and eastern Europe, with the Tozawan stage in Japan, with the late Batesfordian through Balcombian to early Bairnsdalian Australian stages and with the mid-Cliffdenian to mid-Lillburnian New Zealand stages.
Turtles: Meiolania brevicollis Sharks, rays and relatives Chlamydoselachidae: †Chlamydoselachus tobleri Hexanchidae: Hexanchus griseus, Hexanchus nakamurai, Notorynchus cepedianus Perissodactyla Rhinocerotidae: † Dicerorhinus sansaniensis Rodentia Cricetidae: †Karydomys Sciuridae: †Palaeosciurus,? Ratufa Middle Miocene disruption Nördlinger Ries impact crater Gradstein, F. M.. G. & Smith, A. G.. Pareto, L.. PDF GeoWhen Database - Langhian Neogene timescale, at the website of the subcommission for stratigraphic information of the ICS Neogene timescale at the website of the Norwegian network of offshore records of geology and stratigraphy