Perisphinctes is an extinct genus of ammonite cephalopod. They serve as an index fossil for that time period; the species P. boweni was named after geologist E. J. Bowen. Shells of species belonging to this genus have been found in the Jurassic of Antarctica, Chile, Egypt, France, Hungary, Iran, Japan, Poland, Russia, Saudi Arabia, Switzerland, the United Kingdom and Yemen
The Cretaceous is a geologic period and system that spans 79 million years from the end of the Jurassic Period 145 million years ago to the beginning of the Paleogene Period 66 mya. It is the last period of the Mesozoic Era, the longest period of the Phanerozoic Eon; the Cretaceous Period is abbreviated K, for its German translation Kreide. The Cretaceous was a period with a warm climate, resulting in high eustatic sea levels that created numerous shallow inland seas; these oceans and seas were populated with now-extinct marine reptiles and rudists, while dinosaurs continued to dominate on land. During this time, new groups of mammals and birds, as well as flowering plants, appeared; the Cretaceous ended with the Cretaceous–Paleogene extinction event, a large mass extinction in which many groups, including non-avian dinosaurs and large marine reptiles died out. The end of the Cretaceous is defined by the abrupt Cretaceous–Paleogene boundary, a geologic signature associated with the mass extinction which lies between the Mesozoic and Cenozoic eras.
The Cretaceous as a separate period was first defined by Belgian geologist Jean d'Omalius d'Halloy in 1822, using strata in the Paris Basin and named for the extensive beds of chalk, found in the upper Cretaceous of Western Europe. The name Cretaceous was derived from Latin creta; the Cretaceous is divided into Early and Late Cretaceous epochs, or Lower and Upper Cretaceous series. In older literature the Cretaceous is sometimes divided into three series: Neocomian and Senonian. A subdivision in eleven stages, all originating from European stratigraphy, is now used worldwide. In many parts of the world, alternative local subdivisions are still in use; as with other older geologic periods, the rock beds of the Cretaceous are well identified but the exact age of the system's base is uncertain by a few million years. No great extinction or burst of diversity separates the Cretaceous from the Jurassic. However, the top of the system is defined, being placed at an iridium-rich layer found worldwide, believed to be associated with the Chicxulub impact crater, with its boundaries circumscribing parts of the Yucatán Peninsula and into the Gulf of Mexico.
This layer has been dated at 66.043 Ma. A 140 Ma age for the Jurassic-Cretaceous boundary instead of the accepted 145 Ma was proposed in 2014 based on a stratigraphic study of Vaca Muerta Formation in Neuquén Basin, Argentina. Víctor Ramos, one of the authors of the study proposing the 140 Ma boundary age sees the study as a "first step" toward formally changing the age in the International Union of Geological Sciences. From youngest to oldest, the subdivisions of the Cretaceous period are: Late Cretaceous Maastrichtian – Campanian – Santonian – Coniacian – Turonian – Cenomanian – Early Cretaceous Albian – Aptian – Barremian – Hauterivian – Valanginian – Berriasian – The high sea level and warm climate of the Cretaceous meant large areas of the continents were covered by warm, shallow seas, providing habitat for many marine organisms; the Cretaceous was named for the extensive chalk deposits of this age in Europe, but in many parts of the world, the deposits from the Cretaceous are of marine limestone, a rock type, formed under warm, shallow marine circumstances.
Due to the high sea level, there was extensive space for such sedimentation. Because of the young age and great thickness of the system, Cretaceous rocks are evident in many areas worldwide. Chalk is a rock type characteristic for the Cretaceous, it consists of coccoliths, microscopically small calcite skeletons of coccolithophores, a type of algae that prospered in the Cretaceous seas. In northwestern Europe, chalk deposits from the Upper Cretaceous are characteristic for the Chalk Group, which forms the white cliffs of Dover on the south coast of England and similar cliffs on the French Normandian coast; the group is found in England, northern France, the low countries, northern Germany, Denmark and in the subsurface of the southern part of the North Sea. Chalk is not consolidated and the Chalk Group still consists of loose sediments in many places; the group has other limestones and arenites. Among the fossils it contains are sea urchins, belemnites and sea reptiles such as Mosasaurus. In southern Europe, the Cretaceous is a marine system consisting of competent limestone beds or incompetent marls.
Because the Alpine mountain chains did not yet exist in the Cretaceous, these deposits formed on the southern edge of the European continental shelf, at the margin of the Tethys Ocean. Stagnation of deep sea currents in middle Cretaceous times caused anoxic conditions in the sea water leaving the deposited organic matter undecomposed. Half the worlds petroleum reserves were laid down at this time in the anoxic conditions of what would become the Persian Gulf and the Gulf of Mexico. In many places around the world, dark anoxic shales were formed during this interval; these shales are an important source rock for oil and gas, for example in the subsurface of the North Sea. During th
In the geologic timescale, the Bajocian is an age and stage in the Middle Jurassic. It lasted from 170.3 Ma to around 168.3 Ma. The Bajocian age precedes the Bathonian age; the Bajocian stage takes its name from the Latin name of the town of Bayeux, in the region of Normandy in France. The stage was named and introduced in scientific literature by French palaeontologist Alcide d'Orbigny in 1842; the base of the Bajocian stage is defined as the place in the stratigraphic column where fossils of the ammonite genus Hyperlioceras first appear. A global reference profile for the base is located at Murtinheira, close to Cabo Mondego in Portugal; the top of the Bajocian is at the first appearance of ammonite species Parkinsonia convergens. The Bajocian is divided into Lower/Early and Upper/Late subages or substages. In the Tethys domain, the Bajocian contains seven ammonite biozones: zone of Parkinsonia parkinsoni zone of Garantiana garantiana zone of Strenoceras niortense zone of Stephanoceras humphriesianum zone of Sonninia propinquans zone of Witchellia laeviuscula zone of Hyperlioceras discites Gradstein, F.
M.. G. & Smith, A. G.. Alcide d´Orbigny. 1. Terrains oolitiques ou jurassiques, 642 pp. Bertrand, Paris. Pavia, G. & Enay, R.. Sepkoski, J.. Rodríguez-de la Rosa, Rubén A.. "Middle Jurassic ankylosaur tracks from Mexico". Boletín de la Sociedad Geológica Mexicana. 70: 379–395. GeoWhen Database - Bajocian Jurassic-Cretaceous and Lower Jurassic timescales, at the website of the subcommission for stratigraphic information of the ICS Stratigraphic chart of the Upper Jurassic, at the website of Norges Network of offshore records of geology and stratigraphy
In the geologic timescale, the Sinemurian is an age and stage in the Early or Lower Jurassic epoch or series. It spans the time between 199.3 ± 2 Ma and 190.8 ± 1.5 Ma. The Sinemurian is followed by the Pliensbachian. In Europe the Sinemurian age, together with the Hettangian age, saw the deposition of the lower Lias, in Great Britain known as the Blue Lias; the Sinemurian stage was defined and introduced into scientific literature by French palaeontologist Alcide d'Orbigny in 1842. It takes its name from the French town near Dijon; the calcareous soil formed from the Jurassic limestone of the region is in part responsible for the character of the classic Sancerre wines. The base of the Sinemurian stage is at the first appearance of the ammonite genera Vermiceras and Metophioceras in the stratigraphic record. A global reference profile for the Sinemurian stage is located in a cliff north of the hamlet of East Quantoxhead, 6 kilometres east of Watchet, England; the top of the Sinemurian is at the first appearances of the ammonite species Bifericeras donovani and ammonite genus Apoderoceras.
The Sinemurian contains six ammonite biozones in the Tethys domain: zone of Echioceras raricostatum zone of Oxynotoceras oxynotum zone of Asteroceras obtusum zone of Caenisites turneri zone of Arnioceras semicostatum zone of Arietites bucklandi Bloos, G. & Page, K. N.. M.. G. & Smith, A. G.. D´Orbigny, A. C. V. M. D.. 1. Terrains oolitiques ou jurassiques, Paris. Komlosaurus carbonis GeoWhen Database - Sinemurian Lower Jurassic timescale, at the website of the subcommission for stratigraphic information of the ICS Stratigraphic chart of the Lower Jurassic, at the website of Norges Network of offshore records of geology and stratigraphy
Chaoyangsaurus was a marginocephalian dinosaur from the Late Jurassic of China. Chaoyangsaurus belonged to the Ceratopsia, like all ceratopsians, was a herbivore. Chaoyangsaurus was found in the Chaoyang area of Liaoning Province in northeastern China; the specific name honours the Chinese paleontologist C. C. Young. Unlike many other dinosaurs, Chaoyangsaurus had been discussed in a number of sources before its official publication; as a result of this, several different spellings of its name have gone as nomina nuda. The first name to see print was Chaoyoungosaurus, which appeared in the guidebook to a Japanese museum exhibit, was the result of an incorrect transliteration. Zhao used this spelling when he first discussed the species, so it is technically a nomen nudum. Two years Zhao again used this early spelling when he assigned a type specimen and species name, Chaoyoungosaurus liaosiensis. According to Dong, the name Chaoyoungosaurus had been described in a paper by Zhao and Cheng in 1983, but no cite for this supposed paper exists, it is it was not properly published.
Dong, in his 1992 paper on the subject emended the name to the "correct" spelling of Chaoyangosaurus. However, since this renaming was not accompanied by a formal description of the dinosaur, Chaoyangosaurus must be considered a nomen nudum, it was not until 1999 that the dinosaur received an official name. Sereno used the name Chaoyangsaurus in an overview of ceratopsian taxonomy. Once again, that name was a nomen nudum. However, in December of that year, Zhao, Xu published an official description using the name Chaoyangsaurus youngi, as the first name for this genus, not a nomen nudum, it has official priority over all other spellings that have been used. Timeline of ceratopsian research Zhao, X. Cheng, Z. & Xu, X.. "The earliest ceratopsian from the Tuchengzi Formation of Liaoning, China." Journal of Vertebrate Paleontology. 19: 681-691. Http://dinosaurier-info.de/animals/dinosaurs/pages_c/chaoyangsaurus.php Chaoyangsaurus at Dinosaurier-info.de http://fossilworks.org/cgi-bin/bridge.pl?a=taxonInfo&taxon_no=55580 Chaoyangsaurus at Fossilworks.org
Global Boundary Stratotype Section and Point
A Global Boundary Stratotype Section and Point, abbreviated GSSP, is an internationally agreed upon reference point on a stratigraphic section which defines the lower boundary of a stage on the geologic time scale. The effort to define GSSPs is conducted by the International Commission on Stratigraphy, a part of the International Union of Geological Sciences. Most, but not all, GSSPs are based on paleontological changes. Hence GSSPs are described in terms of transitions between different faunal stages, though far more faunal stages have been described than GSSPs; the GSSP definition effort commenced in 1977. As of 2012, 64 of the 101 stages that need a GSSP have been formally defined. A geologic section has to fulfill a set of criteria to be adapted as a GSSP by the ICS; the following list summarizes the criteria: A GSSP has to define the lower boundary of a geologic stage. The lower boundary has to be defined using a primary marker. There should be secondary markers; the horizon in which the marker appears should have minerals.
The marker has to have regional and global correlation in outcrops of the same age The marker should be independent of facies. The outcrop has to have an adequate thickness Sedimentation has to be continuous without any changes in facies The outcrop should be unaffected by tectonic and sedimentary movements, metamorphism The outcrop has to be accessible to research and free to access; this includes that the outcrop has to be located where it can be visited has to be kept in good condition, in accessible terrain, extensive enough to allow repeated sampling and open to researchers of all nationalities. The Precambrian-Cambrian boundary GSSP at Fortune Head, Newfoundland is a typical GSSP, it is set aside as a nature preserve. A continuous section is available from beds that are Precambrian into beds that are Cambrian; the boundary is set at the first appearance of a complex trace fossil Treptichnus pedum, found worldwide. The Fortune Head GSSP is unlikely to be built over. Nonetheless, Treptichnus pedum is less than ideal as a marker fossil as it is not found in every Cambrian sequence, it is not assured that it is found at the same level in every exposure.
In fact, further eroding its value as a boundary marker, it has since been identified in strata 4m below the GSSP! However, no other fossil is known. There is no radiometrically datable bed at the boundary at Fortune Head, but there is one above the boundary in similar beds nearby; these factors have led some geologists to suggest. Once a GSSP boundary has been agreed upon, a "golden spike" is driven into the geologic section to mark the precise boundary for future geologists; the first stratigraphic boundary was defined in 1977 by identifying the Silurian-Devonian boundary with a bronze plaque at a locality called Klonk, northeast of the village of Suchomasty in the Czech Republic. GSSPs are sometimes referred to as Golden Spikes; because defining a GSSP depends on finding well-preserved geologic sections and identifying key events, this task becomes more difficult as one goes farther back in time. Before 630 million years ago, boundaries on the geologic timescale are defined by reference to fixed dates, known as "Global Standard Stratigraphic Ages".
Body form European Mammal Neogene Fauna Geologic time scale New Zealand geologic time scale List of GSSPs North American Land Mammal Age Type locality Hedberg, H. D. International stratigraphic guide: A guide to stratigraphic classification and procedure, New York, John Wiley and Sons, 1976 International Stratigraphic Chart from the International Commission on Stratigraphy GSSP table with pages on each ratified GSSP from the ICS Subcommission for Stratigraphic Information USA National Park Service Washington State University Web Geological Time Machine Eon or Aeon, Math Words - An alphabetical index The Global Boundary Stratotype Section and Point: overview Chart of The Global Boundary Stratotype Sections and Points: chart Table of Global Boundary Stratotype Sections and Points with links to summary pages for each one: chart GSSPs and Continental drift 3D views Geotime chart displaying geologic time periods compared to the fossil record - Deals with chronology and classifications for laymen
Chaoyang is a prefecture-level city of Liaoning province, People's Republic of China. With a vast land area of 20,000 square kilometres, it is by area the largest prefecture-level city in Liaoning, borders on Hebei province and the Inner Mongolia Autonomous Region to the west; the area under Chaoyang's jurisdictional control is split up into two counties, two urban districts, two county-level cities, the Harqin Left Wing Mongolian Autonomous County. The total regional population is 3 million, while the urban centre where the government office is located has a population of 430,000 and forms the core of Chaoyang. Known as China's'fossil city', many important paleontological discoveries have been made in Chaoyang, the Harqin region is the oldest known prehistoric site in northern China. Two of the most remarkable Early Cretaceous birds known to date were recovered in the vicinity of the Jiufotang Formation rocks and named Longipteryx chaoyangensis and Sapeornis chaoyangensis in reference to the city.
The name "Chaoyang" originates from a poem found in one of the oldest collections of Chinese poetry, the Shijing. "A wutong tree grew on a mountain. A fenghuang bird perched at the top and sang towards the morning sun"; the eastern part of Chaoyang is home to a mountain, called Fenghuang Mountain since ancient times. In 1778, this mountain was connected with the poem from the Shijing and Chaoyang was given its current name. Chaoyang has a rich history; the discovery of the over five-thousand-year-old Niuheliang Hongshan Cultural Ruins in the region has drawn attention to Chaoyang as one of the birthplaces of ancient Chinese culture. The area first appears in Chinese historical records as “Liucheng County” in the Early Han period of the 3rd century B. C. In 342 AD, King of the Former Yan, Murong Huang, made Chaoyang his capital under the name Longcheng, the city remained the capital through the Later Yan and Northern Yan periods. Since this time, Chaoyang has functioned as a center of Buddhism in Northeast China, with the construction of Longxiang temple in 345 AD forming the beginning of Buddhist culture in the Northeast.
The Mongols seized surrounding regions. It is difficult to locate nomadic people, but when they submitted to the Manchu Qing Dynasty, Chaoyang was controlled by Chinggisid princes and descendants of Jelme, their territories became Tümed Right Wing Banner, Kharachin Left Wing Banner, Kharachin Right Wing Banner, Kharachin Middle Banner, all of which were under Josutu League. Although the Qin Dynasty prohibited the Chinese from immigrating to Mongol lands, the southernmost league of Mongolia was flooded by Chinese peasants; as a result, several Chinese prefectures were created within the Mongol lands, the Chinese came under the jurisdiction of the neighboring Chengde-fu. In 1891, a Chinese secret society named Jindandao raised a rebellion, massacring tens of thousands of Mongols and forcing survivors to flee northward. Under Manchukuo, the eastern part of Chaoyang, including the city of Chaoyang, belonged to Kin-chow Province while the western part constituted Jehol Province; the People's Republic of China incorporated Chaoyang into Liaoning Province in 1955 although ethnic Mongols wished to join Inner Mongolia.
It was declared a prefecture level city in 1984. Chaoyang has a rather dry, monsoon-influenced humid continental climate, with cold but dry winters, hot, humid summers; the monthly 24-hour average temperature ranges from −9.7 °C in January to 24.8 °C in July, for an annual average of 9.04 °C. A majority of the annual rainfall occurs in August alone. Due to the aridity, diurnal temperature variation is large during spring and autumn, averages 13.3 °C annually. With monthly percent possible sunshine ranging from 50% in July to 71% in January, the city averages 2,748 hours of bright sunshine annually; the prefecture is divided into 7 administrative areas. There are 2 districts, 2 subordinate cities and 3 counties of which one county is an Autonomous County for the Mongolian minority. Agriculture forms the backbone of Chaoyang's economy. In addition to wheat, corn and potatoes, Chaoyang is an important region for the growing of cotton and fruit; the city has begun to venture into the production of shaji, which have become popular in China because of their dual use as food and as medicine.
Chaoyang is home to the largest man-made thicket of shaji. Chaoyang has more than 1,600 industrial enterprises, manufacturing a wide range of products including steel, textiles, diesel engines and paper. Lingyuan Iron and Steel Works and the Liaoning Tyre Factory are two of the largest such enterprises. Liaoning, in particular Chaoyang, has become the focus of great interest in the world of palaeontology. During the 1990s, many new and fascinating fossils were discovered in this region; some of the finds have revolutionised our ideas of dinosaurs and shed new light on the origin of birds. Chaoyang's fossils are in the Jiufotang Formation; these fossils include: Liaoxipterus, a genus of ctenochasmatid pterodactyloid pterosaur from the Lower Cretaceous. Insects have been found such as Dictyoptera, a fossilised cockroach and Hymenoptera, a fossil bee, which date to the Lower Cretaceous period. A local trade in rare fossils has developed in the wake of the finds, with an esti