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Precociality
Precocial species in birds and mammals are those in which the young are relatively mature and mobile from the moment of birth or hatching. They are normally nidifugous, meaning that they leave the nest shortly after birth or hatching. Altricial species are those in which the young are underdeveloped at the time of birth, but with the aid of their parents mature after birth. These categories form a continuum, without distinct gaps between them. In fish, this often refers to the presence or absence of a stomach: precocial larvae have one at the onset of first feeding whereas altricial fish do not. Depending on the species, the larvae may develop a functional stomach during metamorphosis (gastric) or remain stomachless (agastric). Precociality Precocial young have open eyes, hair or down, large brains, and are immediately mobile and somewhat able to flee from or defend themselves against predators. For example, with ground-nesting birds such as ducks or turkeys, the young are r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nidifugous
In biology, nidifugous ( , ) organisms are those that leave the nest shortly after hatching or birth. The term is derived from Latin ''nidus'' for "nest" and ''fugere'', meaning "to flee". The terminology is most often used to describe birds and was introduced by Lorenz Oken in 1816. The chicks of birds in many families, such as the waders, waterfowl, and gamebirds, are usually nidifugous. The opposite of nidifugous organisms are nidicolous ( ; from Latin ''nidus'' "nest" and ''-colus'' "inhabiting") organisms; a nidicolous organism is one which stays at its birthplace for a long time because it depends on its parents for food, protection, and the learning of survival skills. Examples of nidicolous species include mammals and many species of birds. During the life span, the brain of a nidicolous animal expands 8–10 times its initial size; in nidifugous animals, it expands from 1.5 to 2.5 times. Relation to precociality and altriciality Two other terms are also used by scientist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pterosaurs
Pterosaurs are an extinct clade of flying reptiles in the Order (biology), order Pterosauria. They existed during most of the Mesozoic: from the Late Triassic to the end of the Cretaceous (228 million to 66 million years ago). Pterosaurs are the earliest vertebrates known to have evolved flying and gliding animals, powered flight. Their wings were formed by a membrane of skin, muscle, and other tissue (biology), tissues stretching from the ankles to a dramatically lengthened fourth finger. There were two major types of pterosaurs. Basal pterosaurs (also called 'non-pterodactyloid pterosaurs' or 'rhamphorhynchoids') were smaller animals with fully toothed jaws and, typically, long tails. Their wide wing membranes probably included and connected the hind legs. On the ground, they would have had an awkward sprawling posture, but the anatomy of their joints and strong claws would have made them effective climbers, and some may have even lived in trees. Basal pterosaurs were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troodontid
Troodontidae is a clade of bird-like theropod dinosaurs from the Late Jurassic to Late Cretaceous. During most of the 20th century, troodontid fossils were few and incomplete and they have therefore been allied, at various times, with many dinosaurian lineages. More recent fossil discoveries of complete and articulated specimens (including specimens which preserve feathers, eggs, embryos, and complete juveniles), have helped to increase understanding about this group. Anatomical studies, particularly studies of the most primitive troodontids, like '' Sinovenator'', demonstrate striking anatomical similarities with ''Archaeopteryx'' and primitive dromaeosaurids, and demonstrate that they are relatives comprising a clade called Paraves. Evolution The oldest definitive troodontid known is '' Hesperornithoides'' from the Late Jurassic of Wyoming. The slightly older '' Koparion'' of Utah is only represented by a single tooth, and small maniraptoran teeth from the Middle Jurassic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Serengeti
The Serengeti ( ) ecosystem is a geographical region in Africa, spanning the Mara and Arusha Regions of Tanzania. The protected area within the region includes approximately of land, including the Serengeti National Park and several game reserves. The Serengeti hosts one of the world's largest land animal migration (in terms of total body weight), which helps secure it as one of the Seven Natural Wonders of Africa. The Serengeti is also renowned for its large lion population and is one of the best places to observe prides in their natural environment. Approximately 70 large mammal and 500 bird species are found there. This high diversity is a function of diverse habitats, including riverine forests, swamps, kopjes, grasslands, and woodlands. Blue wildebeest, gazelles, zebras, and buffalos are some of the commonly found large mammals in the region. The Serengeti also contains the Serengeti District of Tanzania. The name "Serengeti" is often said to be derived from t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hartebeest
The hartebeest (; ''Alcelaphus buselaphus''), also known as kongoni or kaama, is an Fauna of Africa, African antelope. It is the Monotypic taxon, only member of the genus ''Alcelaphus''. Eight subspecies have been described, including two sometimes considered to be independent species. A large antelope, the hartebeest stands just over at the shoulder, and has a typical head-and-body length of . The weight ranges from . It has a particularly elongated forehead and oddly-shaped horn (anatomy), horns, a short neck, and pointed ears. Its legs, which often have black markings, are unusually long. The animal coat, coat is generally short and shiny. Coat colour varies by the subspecies, from the sandy brown of the western hartebeest to the chocolate brown of the Swayne's hartebeest. Sexual dimorphism, Both sexes of all subspecies have horns, with those of females being more slender. Horns can reach lengths of . Apart from its long face, the large chest and the sharply sloping back di ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Mamba
The black mamba (''Dendroaspis polylepis'') is a species of highly venomous snake belonging to the family Elapidae. It is native to parts of sub-Saharan Africa. First formally species description, described by Albert Günther in 1864, it is the second-longest venomous snake after the king cobra; mature specimens generally exceed and commonly grow to . Specimens of have been reported. It varies in colour from grey to dark brown. Juvenile black mambas tend to be more pale in colour than adults, and darken with age. Despite the common name, the black mamba is not black; the colour name describes rather the inside of its mouth, which it displays when feeling threatened. The species is both terrestrial animal, terrestrial (ground-living) and arboreal (tree-living); it inhabits savannah, woodland, rocky slopes and in some regions, dense forest. It is Diurnality, diurnal and is known to prey on birds and small mammals. Over suitable surfaces, it can move at speeds up to for short ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protobird
"Protobird" is an informal term that has been used by some paleontologists when discussing animals that, while technically classified as non-avian dinosaurs, possess many features normally associated with birds. All protobirds are extinct. Zhou and Farlow (2001), for example, used the term "protobird" for primitive members of the clade Avialae. In this sense, protobirds would include animals like '' Confuciusornis'', '' Sapeornis'', and the Enantiornithes. These animals were small, flying, feathered, and closely related to birds. The authors restricted the term "bird" to refer only to Aves, which they used to mean only modern ("crown group") birds.Zhou, Z. and Farlow, J.O. (2001). "Flight Capability and habits of Confuciusornis." Pp. 237-245 in ''New Perspectives on the Origin and Early Evolution of Birds''. Peabody Museum of Natural History, Yale University, New Haven, USA. Gregory S. Paul used the term "protobird" in a wider sense in 1988, to refer to the extremely bird-like no ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hawk
Hawks are birds of prey of the family Accipitridae. They are very widely distributed and are found on all continents, except Antarctica. The subfamily Accipitrinae includes goshawks, sparrowhawks, sharp-shinned hawks, and others. This subfamily are mainly woodland birds with short broad wings, long tails, and high visual acuity. They hunt by dashing suddenly from a concealed perch. In America, members of the '' Buteo'' group are also called hawks, though birds of this group are called buzzards in other parts of the world. Generally, buteos have broad wings and sturdy builds. They are relatively larger-winged and shorter-tailed than accipiters, and fly further distances in open areas. Buteos descend or pounce on their prey rather than engaging in fast, horizontal pursuit. The terms ''accipitrine hawk'' and ''buteonine hawk'' are used to distinguish between the types in regions where ''hawk'' applies to both. The term ''"true hawk"'' is sometimes used for the accipitrin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black African Baby With Pale Appearance At Birth
Black is a color that results from the absence or complete absorption of visible light. It is an achromatic color, without chroma, like white and grey. It is often used symbolically or figuratively to represent darkness.Eva Heller, ''Psychologie de la couleur – effets et symboliques'', pp. 105–26. Black and white have often been used to describe opposites such as good and evil, the Dark Ages versus the Age of Enlightenment, and night versus day. Since the Middle Ages, black has been the symbolic color of solemnity and authority, and for this reason it is still commonly worn by judges and magistrates. Black was one of the first colors used by artists in Neolithic cave paintings. It was used in ancient Egypt and Greece as the color of the underworld. In the Roman Empire, it became the color of mourning, and over the centuries it was frequently associated with death, evil, witches, and magic. In the 14th century, it was worn by royalty, clergy, judges, and government o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Down Feather
The down of birds is a layer of fine feathers found under the tougher exterior feathers. Very young birds are clad only in down. Powder down is a specialized type of down found only in a few groups of birds. Down is a fine thermal insulator and padding, used in goods such as Down jacket, jackets, bedding (duvets and featherbeds), pillows and sleeping bags. The discovery of feathers trapped in ancient amber suggests that some species of non-avian dinosaur likely possessed down-like feathers. Description and etymology The word ''down'' comes from the Old Norse word ''dúnn'', which had the same meaning as its modern equivalent. The down feather is considered to be the most "straightforward" of all feather types. It has a short or vestigial rachis (shaft), few barb (feather), barbs, and barbules that lack hooks. There are three types of down: natal down, body down and powder down. Natal down is the layer of down feathers that cover most birds at some point in their early developmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
