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Contour Feathers
The pennaceous feather is a type of feather present in most modern birds and in some other species of maniraptoriform dinosaurs. Description A pennaceous feather has a stalk or quill. Its basal part, called a ''calamus'', is embedded in the skin. The calamus is hollow and has pith formed from the dry remains of the feather pulp, and the calamus opens below by an ''inferior umbilicus'' and above by a ''superior umbilicus''. The stalk above the calamus is a solid '' rachis'' having an umbilical groove on its underside. Pennaceous feathers have a rachis with ''vanes'' or ''vaxillum '' spreading to either side. These vanes are composed of a high number of flattened '' barbs'', that are connected to one another with '' barbules''. The barbules are tiny strands that criss-cross on the flattened sides of the barbs. This forms a miniature velcro-like mesh that holds all the barbs together, stabilizing the vanes. Pennaceous feathers on the wing, and elsewhere that stresses related to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rectrice
Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail are called rectrices (), singular rectrix (). The primary function of the flight feathers is to aid in the generation of both thrust and lift, thereby enabling flight. The flight feathers of some birds have evolved to perform additional functions, generally associated with territorial displays, courtship rituals or feeding methods. In some species, these feathers have developed into long showy plumes used in visual courtship displays, while in others they create a sound during display flights. Tiny serrations on the leading edge of their remiges help owls to fly silently (and therefore hunt more successfully), while the extra-stiff rectrices of woodpeckers help them to brace against tree trunks as they hammer on them. Even flightles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Feathered Dinosaurs
A feathered dinosaur is any species of dinosaur possessing feathers. While this includes all species of birds, there is a hypothesis that many, if not all non-avian dinosaur species also possessed feathers in some shape or form. It has been suggested that feathers had originally functioned as thermal insulation, as it remains their function in the down feathers of infant birds today, prior to their eventual modification in birds into structures that support flight. Since scientific research began on dinosaurs in the early 1800s, they were generally believed to be closely related to modern reptiles, such as lizards. The word ''dinosaur'' itself, coined in 1842 by paleontologist Richard Owen, comes from the Greek for 'terrible lizard'. This view began to shift during the so-called dinosaur renaissance in scientific research in the late 1960s, and by the mid-1990s significant evidence had emerged that dinosaurs were much more closely related to birds, which descended directly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bird Flight
Bird flight is the primary mode of locomotion used by most bird species in which birds take off and fly. Flight assists birds with feeding, breeding, avoiding predators, and migrating. Bird flight is one of the most complex forms of locomotion in the animal kingdom. Each facet of this type of motion, including hovering, taking off, and landing, involves many complex movements. As different bird species adapted over millions of years through evolution for specific environments, prey, predators, and other needs, they developed specializations in their wings, and acquired different forms of flight. Various theories exist about how bird flight evolved, including flight from falling or gliding (the ''trees down'' hypothesis), from running or leaping (the ''ground up'' hypothesis), from ''wing-assisted incline running'' or from '' proavis'' (pouncing) behavior. Basic mechanics of bird flight Lift, Drag and Thrust The fundamentals of bird flight are similar to those of aircraft, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wing Loading
In aerodynamics, wing loading is the total mass of an aircraft or flying animal divided by the area of its wing. The stalling speed of an aircraft in straight, level flight is partly determined by its wing loading. An aircraft or animal with a low wing loading has a larger wing area relative to its mass, as compared to one with a high wing loading. The faster an aircraft flies, the more lift can be produced by each unit of wing area, so a smaller wing can carry the same mass in level flight. Consequently, faster aircraft generally have higher wing loadings than slower aircraft. This increased wing loading also increases takeoff and landing distances. A higher wing loading also decreases maneuverability. The same constraints apply to winged biological organisms. Range of wing loadings Effect on performance Wing loading is a useful measure of the stalling speed of an aircraft. Wings generate lift owing to the motion of air around the wing. Larger wings move more air, so an a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adaptation
In biology, adaptation has three related meanings. Firstly, it is the dynamic evolutionary process of natural selection that fits organisms to their environment, enhancing their evolutionary fitness. Secondly, it is a state reached by the population during that process. Thirdly, it is a phenotypic trait or adaptive trait, with a functional role in each individual organism, that is maintained and has evolved through natural selection. Historically, adaptation has been described from the time of the ancient Greek philosophers such as Empedocles and Aristotle. In 18th and 19th century natural theology, adaptation was taken as evidence for the existence of a deity. Charles Darwin proposed instead that it was explained by natural selection. Adaptation is related to biological fitness, which governs the rate of evolution as measured by change in allele frequencies. Often, two or more species co-adapt and co-evolve as they develop adaptations that interlock with those of the oth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rectrices
Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail are called rectrices (), singular rectrix (). The primary function of the flight feathers is to aid in the generation of both thrust and lift, thereby enabling flight. The flight feathers of some birds have evolved to perform additional functions, generally associated with territorial displays, courtship rituals or feeding methods. In some species, these feathers have developed into long showy plumes used in visual courtship displays, while in others they create a sound during display flights. Tiny serrations on the leading edge of their remiges help owls to fly silently (and therefore hunt more successfully), while the extra-stiff rectrices of woodpeckers help them to brace against tree trunks as they hammer on them. Even flightless birds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Remiges
Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail are called rectrices (), singular rectrix (). The primary function of the flight feathers is to aid in the generation of both thrust and lift, thereby enabling flight. The flight feathers of some birds have evolved to perform additional functions, generally associated with territorial displays, courtship rituals or feeding methods. In some species, these feathers have developed into long showy plumes used in visual courtship displays, while in others they create a sound during display flights. Tiny serrations on the leading edge of their remiges help owls to fly silently (and therefore hunt more successfully), while the extra-stiff rectrices of woodpeckers help them to brace against tree trunks as they hammer on them. Even flightless birds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Flight Feather
Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail are called rectrices (), singular rectrix (). The primary function of the flight feathers is to aid in the generation of both thrust and lift (force), lift, thereby enabling bird flight, flight. The flight feathers of some birds have evolved to perform additional functions, generally associated with territorial displays, courtship rituals or feeding methods. In some species, these feathers have developed into long showy plumes used in visual courtship displays, while in others they create a sound during display flights. Tiny serrations on the leading edge of their remiges help owls to fly silently (and therefore hunt more successfully), while the extra-stiff rectrices of woodpeckers help them to brace against tree trunks as they hammer on ... [...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] |
Ulna
The ulna (''pl''. ulnae or ulnas) is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. That is, the ulna is on the same side of the forearm as the little finger. It runs parallel to the radius, the other long bone in the forearm. The ulna is usually slightly longer than the radius, but the radius is thicker. Therefore, the radius is considered to be the larger of the two. Structure The ulna is a long bone found in the forearm that stretches from the elbow to the smallest finger, and when in anatomical position, is found on the medial side of the forearm. It is broader close to the elbow, and narrows as it approaches the wrist. Close to the elbow, the ulna has a bony process, the olecranon process, a hook-like structure that fits into the olecranon fossa of the humerus. This prevents hyperextension and forms a hinge joint with the trochlea of the humerus. There is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Velcro
Velcro, officially known as Velcro IP Holdings LLC and trading as Velcro Companies, is a British privately held company, founded by Swiss electrical engineer George de Mestral in the 1950s. It is the original manufacturer of hook-and-loop fasteners, which de Mestral invented. History Swiss electrical engineer George de Mestral invented his first touch fastener when, in 1941, he went for a walk in the Alps, and wondered why burdock seeds clung to his woolen socks and coat, and also his dog Milka. He discovered it could be turned into something useful. He patented it in 1955, and subsequently refined and developed its practical manufacture until its commercial introduction in the late 1950s. The fastener consisted of two components: a lineal fabric strip with tiny hooks that could 'mate' with another fabric strip with smaller loops, attaching temporarily, until pulled apart. Initially made of cotton, which proved impractical, the fastener was eventually constructed with nylon a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Remige
Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail are called rectrices (), singular rectrix (). The primary function of the flight feathers is to aid in the generation of both thrust and lift, thereby enabling flight. The flight feathers of some birds have evolved to perform additional functions, generally associated with territorial displays, courtship rituals or feeding methods. In some species, these feathers have developed into long showy plumes used in visual courtship displays, while in others they create a sound during display flights. Tiny serrations on the leading edge of their remiges help owls to fly silently (and therefore hunt more successfully), while the extra-stiff rectrices of woodpeckers help them to brace against tree trunks as they hammer on them. Even flightles ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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