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Elsornis
''Elsornis'' is a genus of enantiornithine bird. Only one species is known, ''Elsornis keni''. It lived during the Late Cretaceous. It is known from a partially articulated fossil skeleton found in the Gobi Desert in Mongolia. The holotype fossil is given catalog number MPD - b 100/201. It is in the collection of the Mongolian Palaeontological Center. The fossil was collected at Togrogiin Shiree, South Gobi Aimak, Mongolia; Djadokhta Formation, Late Cretaceous, Campanian. The fossil is extremely well preserved in three dimensions. It preserves a pneumatized Furcula The (Latin for "little fork") or wishbone is a forked bone found in most birds and some species of non-avian dinosaurs, and is formed by the fusion of the two pink clavicles. In birds, its primary function is in the strengthening of the thoracic ..., which was a character previously unknown in enantiornithines. Chiappe et al. (2007) conclude from the proportions of ''Elsornis'' ' pectoral skeleton that it was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enantiornithine
The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over eighty species of Enantiornithes have been named, but some names represent only single bones, so it is likely that not all are valid. The Enantiornithes became extinct at the Cretaceous–Paleogene boundary, along with Hesperornithes and all other non-avian dinosaurs. Discovery and naming The first Enantiornithes to be discovered were incorrectly referred to modern bird groups. For example, the first known species of Enantiornithes, ''Gobipteryx minuta'', was originally considered a paleognath related to ostriches and tinamou. The Enantiornithes were first recognized as a distinct lineage, or "subclass" of birds, by Cyril A. Walker in 1981. Walker mad ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enantiornitheans
The Enantiornithes, also known as enantiornithines or enantiornitheans in literature, are a group of extinct avialans ("birds" in the broad sense), the most abundant and diverse group known from the Mesozoic era. Almost all retained teeth and clawed fingers on each wing, but otherwise looked much like modern birds externally. Over eighty species of Enantiornithes have been named, but some names represent only single bones, so it is likely that not all are valid. The Enantiornithes became extinct at the Cretaceous–Paleogene boundary, along with Hesperornithes and all other non-avian dinosaurs. Discovery and naming The first Enantiornithes to be discovered were incorrectly referred to modern bird groups. For example, the first known species of Enantiornithes, '' Gobipteryx minuta'', was originally considered a paleognath related to ostriches and tinamou. The Enantiornithes were first recognized as a distinct lineage, or "subclass" of birds, by Cyril A. Walker in 1981. Walker ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Djadokhta Formation
The Djadochta Formation (sometimes transcribed and also known as Djadokhta, Djadokata, or Dzhadokhtskaya) is a highly fossiliferous geological formation situated in Central Asia, Gobi Desert, dating from the Late Cretaceous period, about 75 million to 71 million years ago. The type locality is the Bayn Dzak locality, famously known as the Flaming Cliffs. Dinosaur, mammal, and other reptile remains are among the fossils that have been recovered from the formation. Excavation history The Djadochta Formation was first documented and explored—though only a single locality—during paleontological expeditions of the American Museum of Natural History in 1922–1925, which were part of the Central Asiatic Expeditions. The expeditions were led by Roy Chapman Andrews, in company of Walter Willis Granger as chief paleontologist and field team. The team did extensive exploration at the Bayn Dzak (formerly Shabarakh Usu) region, which they nicknamed Flaming Cliffs given that at sunset th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Cretaceous
The Late Cretaceous (100.5–66 Ma) is the younger of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''creta'', the Latin word for the white limestone known as chalk. The chalk of northern France and the white cliffs of south-eastern England date from the Cretaceous Period. Climate During the Late Cretaceous, the climate was warmer than present, although throughout the period a cooling trend is evident. The tropics became restricted to equatorial regions and northern latitudes experienced markedly more seasonal climatic conditions. Geography Due to plate tectonics, the Americas were gradually moving westward, causing the Atlantic Ocean to expand. The Western Interior Seaway divided North America into eastern and western halves; Appalachia and Laramidia. India maintained a northward course towards Asia. In the Southern Hemisphere, Australia and Ant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossil
A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in amber, hair, petrified wood and DNA remnants. The totality of fossils is known as the ''fossil record''. Paleontology is the study of fossils: their age, method of formation, and evolutionary significance. Specimens are usually considered to be fossils if they are over 10,000 years old. The oldest fossils are around 3.48 billion years old to 4.1 billion years old. Early edition, published online before print. The observation in the 19th century that certain fossils were associated with certain rock strata led to the recognition of a geological timescale and the relative ages of different fossils. The development of radiometric dating techniques in the early 20th century allowed scientists to quantitatively measure the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gobi Desert
The Gobi Desert (Chinese: 戈壁 (沙漠), Mongolian: Говь (ᠭᠣᠪᠢ)) () is a large desert or brushland region in East Asia, and is the sixth largest desert in the world. Geography The Gobi measures from southwest to northeast and from north to south. The desert is widest in the west, along the line joining the Lake Bosten and the Lop Nor (87°–89° east). In 2007, it occupied an arc of land in area. In its broadest definition, the Gobi includes the long stretch of desert extending from the foot of the Pamirs (77° east) to the Greater Khingan Mountains, 116–118° east, on the border of Manchuria; and from the foothills of the Altay, Sayan, and Yablonoi mountain ranges on the north to the Kunlun, Altyn-Tagh, and Qilian mountain ranges, which form the northern edges of the Tibetan Plateau, on the south. A relatively large area on the east side of the Greater Khingan range, between the upper waters of the Songhua (Sungari) and the upper waters of the Liao-h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mongolia
Mongolia; Mongolian script: , , ; lit. "Mongol Nation" or "State of Mongolia" () is a landlocked country in East Asia, bordered by Russia to the north and China to the south. It covers an area of , with a population of just 3.3 million, making it the world's most sparsely populated sovereign nation. Mongolia is the world's largest landlocked country that does not border a closed sea, and much of its area is covered by grassy steppe, with mountains to the north and west and the Gobi Desert to the south. Ulaanbaatar, the capital and largest city, is home to roughly half of the country's population. The territory of modern-day Mongolia has been ruled by various nomadic empires, including the Xiongnu, the Xianbei, the Rouran, the First Turkic Khaganate, and others. In 1206, Genghis Khan founded the Mongol Empire, which became the largest contiguous land empire in history. His grandson Kublai Khan conquered China proper and established the Yuan dynasty. After the co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holotype
A holotype is a single physical example (or illustration) of an organism, known to have been used when the species (or lower-ranked taxon) was formally described. It is either the single such physical example (or illustration) or one of several examples, but explicitly designated as the holotype. Under the International Code of Zoological Nomenclature (ICZN), a holotype is one of several kinds of name-bearing types. In the International Code of Nomenclature for algae, fungi, and plants (ICN) and ICZN, the definitions of types are similar in intent but not identical in terminology or underlying concept. For example, the holotype for the butterfly '' Plebejus idas longinus'' is a preserved specimen of that subspecies, held by the Museum of Comparative Zoology at Harvard University. In botany, an isotype is a duplicate of the holotype, where holotype and isotypes are often pieces from the same individual plant or samples from the same gathering. A holotype is not necessarily "typ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Campanian
The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian spans the time from 83.6 (± 0.2) to 72.1 (± 0.2) million years ago. It is preceded by the Santonian and it is followed by the Maastrichtian. The Campanian was an age when a worldwide sea level rise covered many coastal areas. The morphology of some of these areas has been preserved: it is an unconformity beneath a cover of marine sedimentary rocks. Etymology The Campanian was introduced in scientific literature by Henri Coquand in 1857. It is named after the French village of Champagne in the department of Charente-Maritime. The original type locality was a series of outcrop near the village of Aubeterre-sur-Dronne in the same region. Definition The base of the Campanian Stage is defined as a place in the stratigraphic column wher ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pneumatized Bones
Skeletal pneumaticity is the presence of air spaces within bones. It is generally produced during development by excavation of bone by pneumatic diverticula (air sacs) from an air-filled space, such as the lungs or nasal cavity. Pneumatization is highly variable between individuals, and bones not normally pneumatized can become pneumatized in pathological development. Cranial pneumaticity Pneumatization occurs in the skulls of mammals, crocodilians and birds among extant tetrapods. Pneumatization has been documented in extinct archosaurs including dinosaurs and pterosaurs. Pneumatic spaces include the paranasal sinuses and some of the mastoid cells. Postcranial pneumaticity Postcranial pneumaticity is found largely in certain archosaur groups, namely dinosaurs, pterosaurs, and birds. Vertebral pneumatization is widespread among saurischian dinosaurs, and some theropods have quite widespread pneumatization, for example ''Aerosteon riocoloradensis'' has pneumatization of the ilium ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Furcula
The (Latin for "little fork") or wishbone is a forked bone found in most birds and some species of non-avian dinosaurs, and is formed by the fusion of the two pink clavicles. In birds, its primary function is in the strengthening of the thoracic skeleton to withstand the rigors of flight. In birds The furcula works as a strut between a bird's shoulders, and articulates to each of the bird's scapulae. In conjunction with the coracoid and the scapula, it forms a unique structure called the triosseal canal, which houses a strong tendon that connects the supracoracoideus muscles to the humerus. This system is responsible for lifting the wings during the recovery stroke. As the thorax is compressed by the flight muscles during downstroke, the upper ends of the furcula spread apart, expanding by as much as 50% of its resting width, and then contracts. X-ray films of starlings in flight have shown that in addition to strengthening the thorax, the furcula acts like a spring in the pe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Avisauridae
Avisauridae is a family of extinct enantiornithine dinosaurs from the Cretaceous period, distinguished by several features of their ankle bones. Depending on the definition used, Avisauridae is either a broad and widespread group of advanced enantiornithines (following Cau & Arduini, 2008), or a small family within that group, restricted to species from the Late Cretaceous of North and South America (following Chiappe, 1992). Description Avisaurids were among the largest and last enantiornithines to have lived, although they are also among the most poorly preserved. The majority of them are known primarily from fossilized tarsometatarsal bones, the part of a bird's leg formed by fused metatarsals (the bones which comprise the foot in humans). As a result, members of this family are distinguished from other enantiornithines exclusively by features of the tarsometatarsal and pedal phalanges (toe bones). Unlike in some prehistoric birds, avisaurid tarsometatarsals were not comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
