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Praeornis
''Praeornis'' is a dubious genus of early avialan or bird-like dinosaur, named on the basis of a single feather discovered in the Karabastau Formation of Kazakhstan by Sharov in 1971. A second specimen was discovered in 2010 by Dzik et al. The feathers of ''Praeornis'' likely represent modified tail feathers used for display or balance, similar to those found in some other early avialans. The feathers of ''Praeornis'' are unique thanks to their extremely thick central quill (rachis) and stiffened barbs. History In 1978, Rautian officially named the feather (cataloged as specimen PIN 2585/32) ''Praeornis sharovi''. He believed it belonged to a bird more primitive than ''Archaeopteryx'', and assigned it to its own subclass (Praeornithes), order (Praeornithiformes) and family (Praeornithidae). However, in 1986, Bock published a paper arguing that the "feather" was in fact the leaf of a cycad. This opinion was followed by Doludenko and colleagues in 1990, who noted that it was simil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Karabastau Formation
The Karabastau Formation ( kk, Qarabastaý svıtasy) is a geological formation and lagerstätte in the Karatau Mountains of southern Kazakhstan whose strata date to the Middle to Late Jurassic. It is an important locality for insect fossils that has been studied since the early 20th century, alongside the rarer remains of vertebrates, including pterosaurs, salamanders, lizards and crocodiles.Barrett, P.M., Butler, R.J., Edwards, N.P., & Milner, A.R. Pterosaur distribution in time and space: an atlas. p61-107. in Flugsaurier: Pterosaur papers in honour of Peter Wellnhofer. 2008. Hone, D.W.E., and Buffetaut, E. (eds). Zitteliana B, 28. 264p/ref> Lithology and depositional environment The primary lithology consists of 1 mm thick varve laminations of claystone, with a dark part and a light dolomitic part, which probably correspond to a wet and dry season respectively, alongside rare, several cm thick sandstone interbeds. These were deposited within an ancient freshwater paleol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Late Jurassic
The Late Jurassic is the third epoch of the Jurassic Period, and it spans the geologic time from 163.5 ± 1.0 to 145.0 ± 0.8 million years ago (Ma), which is preserved in Upper Jurassic strata.Owen 1987. In European lithostratigraphy, the name "Malm" indicates rocks of Late Jurassic age. In the past, ''Malm'' was also used to indicate the unit of geological time, but this usage is now discouraged to make a clear distinction between lithostratigraphic and geochronologic/chronostratigraphic units. Subdivisions The Late Jurassic is divided into three ages, which correspond with the three (faunal) stages of Upper Jurassic rock: Paleogeography During the Late Jurassic Epoch, Pangaea broke up into two supercontinents, Laurasia to the north, and Gondwana to the south. The result of this break-up was the spawning of the Atlantic Ocean. However, at this time, the Atlantic Ocean was relatively narrow. Life forms of the epoch This epoch is well known for many famous types of dinosau ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peter Wellnhofer
Peter Wellnhofer (born Munich, 1936) is a German paleontologist at the Bayerische Staatssammlung fur Paläontologie in Munich. He is best known for his work on the various fossil specimens of ''Archaeopteryx'' or "Urvogel", the first known bird. Wellnhofer's other work includes ''The Illustrated Encyclopedia of Pterosaurs'' from 1991. ''Wellnhoferia'', a bird closely related to ''Archaeopteryx'', or a species of the Urvogel itself, was named in his honour in 2001. The pterosaur ''Wellnhopterus'' was named in his honour in 2021. In 2007 a special meeting of pterosaur experts in Munich was dedicated to Wellnhofer, describing him as "the foremost authority on pterosaurs for the last four decades." The meeting produced a festschrift In academia, a ''Festschrift'' (; plural, ''Festschriften'' ) is a book honoring a respected person, especially an academic, and presented during their lifetime. It generally takes the form of an edited volume, containing contributions from the h ... in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cycads
Cycads are seed plants that typically have a stout and woody (ligneous) trunk with a crown of large, hard, stiff, evergreen and (usually) pinnate leaves. The species are dioecious, that is, individual plants of a species are either male or female. Cycads vary in size from having trunks only a few centimeters to several meters tall. They typically grow very slowly and live very long. Because of their superficial resemblance, they are sometimes mistaken for palms or ferns, but they are not closely related to either group. Cycads are gymnosperms (naked-seeded), meaning their unfertilized seeds are open to the air to be directly fertilized by pollination, as contrasted with angiosperms, which have enclosed seeds with more complex fertilization arrangements. Cycads have very specialized pollinators, usually a specific species of beetle. Both male and female cycads bear cones (strobili), somewhat similar to conifer cones. Cycads have been reported to fix nitrogen in associatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prehistoric Avialans
Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of symbols, marks, and images appears very early among humans, but the earliest known writing systems appeared 5000 years ago. It took thousands of years for writing systems to be widely adopted, with writing spreading to almost all cultures by the 19th century. The end of prehistory therefore came at very different times in different places, and the term is less often used in discussing societies where prehistory ended relatively recently. In the early Bronze Age, Sumer in Mesopotamia, the Indus Valley Civilisation, and ancient Egypt were the first civilizations to develop their own scripts and to keep historical records, with their neighbors following. Most other civilizations reached the end of prehistory during the following Iron Age. T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fossils Of Kazakhstan
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 absol ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rachis
In biology, a rachis (from the grc, ῥάχις [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the ''rachis'' usually forms the supporting axis of the body and is then called the spine or vertebral column. ''Rachis'' can also mean the central shaft of pennaceous feathers. In the gonad of the invertebrate nematode '' Caenorhabditis elegans'', a rachis is the central cell-free core or axis of the gonadal arm of both adult males and hermaphrodites where the germ cells have achieved pachytene and are attached to the walls of the gonadal tube. The rachis is filled with cytoplasm. In botany In plants, a rachis is the main axis of a compound structure. It can be the main stem of a compound leaf, such as in ''Acacia'' or ferns, or the main, flower-bearing portion of an inflorescence above a supporting peduncle. Where it subdivides ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enantiornithes
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] |
Longisquama
''Longisquama'' is a genus of extinct reptile. There is only one species, ''Longisquama insignis'', known from a poorly preserved skeleton and several incomplete fossil impressions from the Middle to Late Triassic Madygen Formation in Kyrgyzstan. It is known from the type fossil specimen, slab and counterslab (PIN 2548/4 and PIN 2584/5) and five referred specimens of possible integumentary appendages (PIN 2584/7 through 9). All specimens are in the collection of the Paleontological Institute of the Russian Academy of Sciences in Moscow. ''Longisquama'' means "long scales"; the specific name ''insignis'' refers to its small size. The ''Longisquama'' holotype is notable for a number of long structures that appear to grow from its skin. The current opinion is that ''Longisquama'' is an ambiguous diapsid and has no bearing on the origin of birds. History Interpretation Researchers Haubold and Buffetaut believed that the structures were long, modified scales attached in pairs t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yevgeny Kurochkin
Yevgeny Nikolayevich Kurochkin (Евгений Николаевич Курочкин; 12 July 1940 - 13 December 2011) was a Russian paleornithologist at the Paleontological Institute of the Russian Academy of Sciences. He served as President of the Menzbier Ornithological Society. He graduated from the Moscow State University in 1964. Most of his field work was done in Central Asia, Mongolia, Cuba, and Vietnam. In 1982, Kurochkin described '' Ambiortus'', which he thought to be the oldest ornithurine (modern-type bird). Kurochkin named the new species after his peer Georgi Petrovich Dementyev (1898-1969). In 2011, Kurochkin and Gareth J. Dyke described ''Eostrix tsaganica'' found in Mongolia, the first find of this primitive owl in Asia. Opposing the theropod origin of modern birds, Kurochkin maintained that archosaurs and dinosaurs were two distinct lineages. He repeatedly questioned the assumption that Archaeopteryx and Enantiornithes were early birds. According to Kurochkin, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ratite
A ratite () is any of a diverse group of flightless, large, long-necked, and long-legged birds of the infraclass Palaeognathae. Kiwi, the exception, are much smaller and shorter-legged and are the only nocturnal extant ratites. The systematics of and relationships within the paleognath clade have been in flux. Previously, all the flightless members had been assigned to the order Struthioniformes, which is more recently regarded as containing only the ostrich. The modern bird superorder Palaeognathae consists of ratites and the flighted Neotropic tinamous (compare to Neognathae). Unlike other flightless birds, the ratites have no keel on their sternum — hence the name, from the Latin ''ratis'' (raft, a vessel which has no keel - in contradistinction to extant flighted birds with a keel). Without this to anchor their wing muscles, they could not have flown even if they developed suitable wings. Ratites are a paraphyletic group; tinamous fall within them, and are the sister gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Electron Microscope
An electron microscope is a microscope that uses a beam of accelerated electrons as a source of illumination. As the wavelength of an electron can be up to 100,000 times shorter than that of visible light photons, electron microscopes have a higher resolving power than light microscopes and can reveal the structure of smaller objects. A scanning transmission electron microscope has achieved better than 50 pm resolution in annular dark-field imaging mode and magnifications of up to about 10,000,000× whereas most light microscopes are limited by diffraction to about 200 nm resolution and useful magnifications below 2000×. Electron microscopes use shaped magnetic fields to form electron optical lens systems that are analogous to the glass lenses of an optical light microscope. Electron microscopes are used to investigate the ultrastructure of a wide range of biological and inorganic specimens including microorganisms, cells, large molecules, biopsy samples, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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