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4,300 | At the time of its original publication in 1943, there was no empirical evidence to support the theory. | https://en.wikipedia.org/wiki?curid=163131 |
4,301 | Maslow's hierarchy of needs has widespread influence outside academia, perhaps because it explains things "that most humans immediately recognize in themselves and others." Still, academically, Maslow's idea is heavily contested. Although recent research appears to validate the existence of universal human needs, as we... | https://en.wikipedia.org/wiki?curid=163131 |
4,302 | Maslow studied people such as Albert Einstein, Jane Addams, Eleanor Roosevelt, and Baruch Spinoza, rather than mentally ill or neurotic people, writing that "the study of crippled, stunted, immature, and unhealthy specimens can yield only a cripple psychology and a cripple philosophy." Maslow studied the healthiest 1% ... | https://en.wikipedia.org/wiki?curid=163131 |
4,303 | In a 1976 review of Maslow's hierarchy of needs, little evidence was found for the specific ranking of needs that Maslow described or for the existence of a definite hierarchy at all. This refutation was claimed to be supported by the majority of longitudinal data and cross-sectional studies at the time, with the limit... | https://en.wikipedia.org/wiki?curid=163131 |
4,304 | In 1984, the order in which the hierarchy is arranged was criticized as being ethnocentric by Geert Hofstede. In turn, Hofstede's work was criticized by others. Maslow's hierarchy of needs was argued as failing to illustrate and expand upon the difference between the social and intellectual needs of those raised in ind... | https://en.wikipedia.org/wiki?curid=163131 |
4,305 | Criticisms towards the theory have also been expressed on the lack of consideration towards individualism and collectivism in the context of spirituality. | https://en.wikipedia.org/wiki?curid=163131 |
4,306 | The position and value of sex on the pyramid have also been a source of criticism regarding Maslow's hierarchy. Maslow's hierarchy places sex in the needs category (above) along with food and breathing; it lists sex solely from an individualistic perspective. For example, sex is placed with other physiological needs wh... | https://en.wikipedia.org/wiki?curid=163131 |
4,307 | The higher-order (self-esteem and self-actualization) and lower-order (physiological, safety, and love) need classification of Maslow's hierarchy of needs is not universal and may vary across cultures due to individual differences and availability of resources in the region or geopolitical entity/country. | https://en.wikipedia.org/wiki?curid=163131 |
4,308 | In a 1997 study, exploratory factor analysis (EFA) of a thirteen-item scale showed there were two particularly important levels of needs in the US during the peacetime of 1993 to 1994: survival (physiological and safety) and psychological (love, self-esteem, and self-actualization). In 1991, a retrospective peacetime m... | https://en.wikipedia.org/wiki?curid=163131 |
4,309 | Changes regarding the importance and satisfaction of needs from the retrospective peacetime to wartime due to stress varied significantly across cultures (the US vs. the Middle East). For the US citizens, there was only one level of needs, since all needs were considered equally important. With regards to satisfaction ... | https://en.wikipedia.org/wiki?curid=163131 |
4,310 | A study of the ordering of needs in Asia found differences between the ordering of lower and higher order needs. For instance, community (related to belongingness and considered a lower order need in Maslow's hierarchy) was found to be the highest order need across Asia, followed closely by self-acceptance and growth. | https://en.wikipedia.org/wiki?curid=163131 |
4,311 | A 1981 study looked at how Maslow's hierarchy might vary across age groups. A survey asked participants of varying ages to rate a set number of statements from most important to least important. The researchers found that children had higher physical need scores than the other groups, the love need emerged from childho... | https://en.wikipedia.org/wiki?curid=163131 |
4,312 | Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the evolution of dinosaurs is the subject of active research. They became the dominant terrestrial vertebrates after ... | https://en.wikipedia.org/wiki?curid=8311 |
4,313 | Dinosaurs are varied from taxonomic, morphological and ecological standpoints. Birds, at over 10,700 living species, are among the most diverse group of vertebrates. Using fossil evidence, paleontologists have identified over 900 distinct genera and more than 1,000 different species of non-avian dinosaurs. Dinosaurs ar... | https://en.wikipedia.org/wiki?curid=8311 |
4,314 | While dinosaurs were ancestrally bipedal, many extinct groups included quadrupedal species, and some were able to shift between these stances. Elaborate display structures such as horns or crests are common to all dinosaur groups, and some extinct groups developed skeletal modifications such as bony armor and spines. W... | https://en.wikipedia.org/wiki?curid=8311 |
4,315 | The first dinosaur fossils were recognized in the early 19th century, with the name "dinosaur" (meaning "terrible lizard") being coined by Sir Richard Owen in 1841 to refer to these "great fossil lizards". Since then, mounted fossil dinosaur skeletons have been major attractions at museums worldwide, and dinosaurs have... | https://en.wikipedia.org/wiki?curid=8311 |
4,316 | Under phylogenetic nomenclature, dinosaurs are usually defined as the group consisting of the most recent common ancestor (MRCA) of "Triceratops" and modern birds (Neornithes), and all its descendants. It has also been suggested that Dinosauria be defined with respect to the MRCA of "Megalosaurus" and "Iguanodon", beca... | https://en.wikipedia.org/wiki?curid=8311 |
4,317 | Birds are now recognized as being the sole surviving lineage of theropod dinosaurs. In traditional taxonomy, birds were considered a separate class that had evolved from dinosaurs, a distinct superorder. However, a majority of contemporary paleontologists concerned with dinosaurs reject the traditional style of classif... | https://en.wikipedia.org/wiki?curid=8311 |
4,318 | Research by Matthew G. Baron, David B. Norman, and Paul M. Barrett in 2017 suggested a radical revision of dinosaurian systematics. Phylogenetic analysis by Baron "et al." recovered the Ornithischia as being closer to the Theropoda than the Sauropodomorpha, as opposed to the traditional union of theropods with sauropod... | https://en.wikipedia.org/wiki?curid=8311 |
4,319 | Using one of the above definitions, dinosaurs can be generally described as archosaurs with hind limbs held erect beneath the body. Other prehistoric animals, including pterosaurs, mosasaurs, ichthyosaurs, plesiosaurs, and "Dimetrodon", while often popularly conceived of as dinosaurs, are not taxonomically classified a... | https://en.wikipedia.org/wiki?curid=8311 |
4,320 | Dinosaurs were the dominant terrestrial vertebrates of the Mesozoic Era, especially the Jurassic and Cretaceous periods. Other groups of animals were restricted in size and niches; mammals, for example, rarely exceeded the size of a domestic cat, and were generally rodent-sized carnivores of small prey. They have alway... | https://en.wikipedia.org/wiki?curid=8311 |
4,321 | In 2016, the estimated number of dinosaur species that existed in the Mesozoic was 1,543–2,468. In 2021, the number of modern-day birds (avian dinosaurs) was estimated to be at 10,806 species. Some are herbivorous, others carnivorous, including seed-eaters, fish-eaters, insectivores, and omnivores. While dinosaurs were... | https://en.wikipedia.org/wiki?curid=8311 |
4,322 | While recent discoveries have made it more difficult to present a universally agreed-upon list of their distinguishing features, nearly all dinosaurs discovered so far share certain modifications to the ancestral archosaurian skeleton, or are clearly descendants of older dinosaurs showing these modifications. Although ... | https://en.wikipedia.org/wiki?curid=8311 |
4,323 | A detailed assessment of archosaur interrelations by Sterling Nesbitt confirmed or found the following twelve unambiguous synapomorphies, some previously known: | https://en.wikipedia.org/wiki?curid=8311 |
4,324 | Nesbitt found a number of further potential synapomorphies and discounted a number of synapomorphies previously suggested. Some of these are also present in silesaurids, which Nesbitt recovered as a sister group to Dinosauria, including a large anterior trochanter, metatarsals II and IV of subequal length, reduced cont... | https://en.wikipedia.org/wiki?curid=8311 |
4,325 | A variety of other skeletal features are shared by dinosaurs. However, because they are either common to other groups of archosaurs or were not present in all early dinosaurs, these features are not considered to be synapomorphies. For example, as diapsids, dinosaurs ancestrally had two pairs of Infratemporal fenestrae... | https://en.wikipedia.org/wiki?curid=8311 |
4,326 | Dinosaurs stand with their hind limbs erect in a manner similar to most modern mammals, but distinct from most other reptiles, whose limbs sprawl out to either side. This posture is due to the development of a laterally facing recess in the pelvis (usually an open socket) and a corresponding inwardly facing distinct he... | https://en.wikipedia.org/wiki?curid=8311 |
4,327 | Dinosaur fossils have been known for millennia, although their true nature was not recognized. The Chinese considered them to be dragon bones and documented them as such. For example, "Huayang Guo Zhi" (), a gazetteer compiled by Chang Qu () during the Western Jin Dynasty (265–316), reported the discovery of dragon bon... | https://en.wikipedia.org/wiki?curid=8311 |
4,328 | Scholarly descriptions of what would now be recognized as dinosaur bones first appeared in the late 17th century in England. Part of a bone, now known to have been the femur of a "Megalosaurus", was recovered from a limestone quarry at Cornwell near Chipping Norton, Oxfordshire, in 1676. The fragment was sent to Robert... | https://en.wikipedia.org/wiki?curid=8311 |
4,329 | Between 1815 and 1824, the Rev William Buckland, the first Reader of Geology at the University of Oxford, collected more fossilized bones of "Megalosaurus" and became the first person to describe a non-avian dinosaur in a scientific journal. The second non-avian dinosaur genus to be identified, "Iguanodon", was discove... | https://en.wikipedia.org/wiki?curid=8311 |
4,330 | The study of these "great fossil lizards" soon became of great interest to European and American scientists, and in 1841 the English paleontologist Sir Richard Owen coined the term "dinosaur", using it to refer to the "distinct tribe or sub-order of Saurian Reptiles" that were then being recognized in England and aroun... | https://en.wikipedia.org/wiki?curid=8311 |
4,331 | In 1858, William Parker Foulke discovered the first known American dinosaur, in marl pits in the small town of Haddonfield, New Jersey. (Although fossils had been found before, their nature had not been correctly discerned.) The creature was named "Hadrosaurus foulkii". It was an extremely important find: "Hadrosaurus"... | https://en.wikipedia.org/wiki?curid=8311 |
4,332 | Dinosaur mania was exemplified by the fierce rivalry between Edward Drinker Cope and Othniel Charles Marsh, both of whom raced to be the first to find new dinosaurs in what came to be known as the Bone Wars. This fight between the two scientists lasted for over 30 years, ending in 1897 when Cope died after spending his... | https://en.wikipedia.org/wiki?curid=8311 |
4,333 | The field of dinosaur research has enjoyed a surge in activity that began in the 1970s and is ongoing. This was triggered, in part, by John Ostrom's discovery and 1969 description of "Deinonychus", an active predator that may have been warm-blooded, in marked contrast to the then-prevailing image of dinosaurs as sluggi... | https://en.wikipedia.org/wiki?curid=8311 |
4,334 | One of the best examples of soft-tissue impressions in a fossil dinosaur was discovered in the Pietraroja Plattenkalk in southern Italy. The discovery was reported in 1998, and described the specimen of a small, juvenile coelurosaur, "Scipionyx samniticus". The fossil includes portions of the intestines, colon, liver, ... | https://en.wikipedia.org/wiki?curid=8311 |
4,335 | In the March 2005 issue of "Science", the paleontologist Mary Higby Schweitzer and her team announced the discovery of flexible material resembling actual soft tissue inside a 68-million-year-old "Tyrannosaurus rex" leg bone from the Hell Creek Formation in Montana. After recovery, the tissue was rehydrated by the scie... | https://en.wikipedia.org/wiki?curid=8311 |
4,336 | In 2009, a team including Schweitzer announced that, using even more careful methodology, they had duplicated their results by finding similar soft tissue in a duck-billed dinosaur, "Brachylophosaurus canadensis", found in the Judith River Formation of Montana. This included even more detailed tissue, down to preserved... | https://en.wikipedia.org/wiki?curid=8311 |
4,337 | The extraction of ancient DNA from dinosaur fossils has been reported on two separate occasions; upon further inspection and peer review, however, neither of these reports could be confirmed. However, a functional peptide involved in the vision of a theoretical dinosaur has been inferred using analytical phylogenetic r... | https://en.wikipedia.org/wiki?curid=8311 |
4,338 | In 2015, researchers reported finding structures similar to blood cells and collagen fibers, preserved in the bone fossils of six Cretaceous dinosaur specimens, which are approximately 75 million years old. | https://en.wikipedia.org/wiki?curid=8311 |
4,339 | Dinosaurs diverged from their archosaur ancestors during the Middle to Late Triassic epochs, roughly 20 million years after the devastating Permian–Triassic extinction event wiped out an estimated 96% of all marine species and 70% of terrestrial vertebrate species approximately 252 million years ago. Radiometric dating... | https://en.wikipedia.org/wiki?curid=8311 |
4,340 | When dinosaurs appeared, they were not the dominant terrestrial animals. The terrestrial habitats were occupied by various types of archosauromorphs and therapsids, like cynodonts and rhynchosaurs. Their main competitors were the pseudosuchians, such as aetosaurs, ornithosuchids and rauisuchians, which were more succes... | https://en.wikipedia.org/wiki?curid=8311 |
4,341 | Dinosaur evolution after the Triassic followed changes in vegetation and the location of continents. In the Late Triassic and Early Jurassic, the continents were connected as the single landmass Pangaea, and there was a worldwide dinosaur fauna mostly composed of coelophysoid carnivores and early sauropodomorph herbivo... | https://en.wikipedia.org/wiki?curid=8311 |
4,342 | By the Early Cretaceous and the ongoing breakup of Pangaea, dinosaurs were becoming strongly differentiated by landmass. The earliest part of this time saw the spread of ankylosaurians, iguanodontians, and brachiosaurids through Europe, North America, and northern Africa. These were later supplemented or replaced in Af... | https://en.wikipedia.org/wiki?curid=8311 |
4,343 | There were three general dinosaur faunas in the Late Cretaceous. In the northern continents of North America and Asia, the major theropods were tyrannosaurids and various types of smaller maniraptoran theropods, with a predominantly ornithischian herbivore assemblage of hadrosaurids, ceratopsians, ankylosaurids, and pa... | https://en.wikipedia.org/wiki?curid=8311 |
4,344 | The Cretaceous–Paleogene extinction event, which occurred approximately 66 million years ago at the end of the Cretaceous, caused the extinction of all dinosaur groups except for the neornithine birds. Some other diapsid groups, including crocodilians, dyrosaurs, sebecosuchians, turtles, lizards, snakes, sphenodontians... | https://en.wikipedia.org/wiki?curid=8311 |
4,345 | The surviving lineages of neornithine birds, including the ancestors of modern ratites, ducks and chickens, and a variety of waterbirds, diversified rapidly at the beginning of the Paleogene period, entering ecological niches left vacant by the extinction of Mesozoic dinosaur groups such as the arboreal enantiornithine... | https://en.wikipedia.org/wiki?curid=8311 |
4,346 | Dinosaurs belong to a group known as archosaurs, which also includes modern crocodilians. Within the archosaur group, dinosaurs are differentiated most noticeably by their gait. Dinosaur legs extend directly beneath the body, whereas the legs of lizards and crocodilians sprawl out to either side. | https://en.wikipedia.org/wiki?curid=8311 |
4,347 | Collectively, dinosaurs as a clade are divided into two primary branches, Saurischia and Ornithischia. Saurischia includes those taxa sharing a more recent common ancestor with birds than with Ornithischia, while Ornithischia includes all taxa sharing a more recent common ancestor with "Triceratops" than with Saurischi... | https://en.wikipedia.org/wiki?curid=8311 |
4,348 | By contrast, ornithischians—"bird-hipped", from the Greek "ornitheios" (ὀρνίθειος) meaning "of a bird" and "ischion" (ἰσχίον) meaning "hip joint"—had a pelvis that superficially resembled a bird's pelvis: the pubic bone was oriented caudally (rear-pointing). Unlike birds, the ornithischian pubis also usually had an add... | https://en.wikipedia.org/wiki?curid=8311 |
4,349 | Despite the terms "bird hip" (Ornithischia) and "lizard hip" (Saurischia), birds are not part of Ornithischia. Birds instead belong to Saurischia, the “lizard-hipped” dinosaurs—birds evolved from earlier dinosaurs with "lizard hips". | https://en.wikipedia.org/wiki?curid=8311 |
4,350 | The following is a simplified classification of dinosaur groups based on their evolutionary relationships, and those of the main dinosaur groups Theropoda, Sauropodomorpha and Ornithischia, compiled by Justin Tweet. Further details and other hypotheses of classification may be found on individual articles. | https://en.wikipedia.org/wiki?curid=8311 |
4,351 | Knowledge about dinosaurs is derived from a variety of fossil and non-fossil records, including fossilized bones, feces, trackways, gastroliths, feathers, impressions of skin, internal organs and other soft tissues. Many fields of study contribute to our understanding of dinosaurs, including physics (especially biomech... | https://en.wikipedia.org/wiki?curid=8311 |
4,352 | Current evidence suggests that dinosaur average size varied through the Triassic, Early Jurassic, Late Jurassic and Cretaceous. Predatory theropod dinosaurs, which occupied most terrestrial carnivore niches during the Mesozoic, most often fall into the category when sorted by estimated weight into categories based on o... | https://en.wikipedia.org/wiki?curid=8311 |
4,353 | The sauropods were the largest and heaviest dinosaurs. For much of the dinosaur era, the smallest sauropods were larger than anything else in their habitat, and the largest was an order of magnitude more massive than anything else that has since walked the Earth. Giant prehistoric mammals such as "Paraceratherium" (the... | https://en.wikipedia.org/wiki?curid=8311 |
4,354 | Scientists will probably never be certain of the largest and smallest dinosaurs to have ever existed. This is because only a tiny percentage of animals were ever fossilized and most of these remain buried in the earth. Few of the specimens that are recovered are complete skeletons, and impressions of skin and other sof... | https://en.wikipedia.org/wiki?curid=8311 |
4,355 | The tallest and heaviest dinosaur known from good skeletons is "Giraffatitan brancai" (previously classified as a species of "Brachiosaurus"). Its remains were discovered in Tanzania between 1907 and 1912. Bones from several similar-sized individuals were incorporated into the skeleton now mounted and on display at the... | https://en.wikipedia.org/wiki?curid=8311 |
4,356 | There were larger dinosaurs, but knowledge of them is based entirely on a small number of fragmentary fossils. Most of the largest herbivorous specimens on record were discovered in the 1970s or later, and include the massive "Argentinosaurus", which may have weighed to kilograms (90 to 110 short tons) and reached len... | https://en.wikipedia.org/wiki?curid=8311 |
4,357 | The largest carnivorous dinosaur was "Spinosaurus", reaching a length of , and weighing . Other large carnivorous theropods included "Giganotosaurus", "Carcharodontosaurus" and "Tyrannosaurus". "Therizinosaurus" and "Deinocheirus" were among the tallest of the theropods. The largest ornithischian dinosaur was probably ... | https://en.wikipedia.org/wiki?curid=8311 |
4,358 | The smallest dinosaur known is the bee hummingbird, with a length of only and mass of around . The smallest known non-avialan dinosaurs were about the size of pigeons and were those theropods most closely related to birds. For example, "Anchiornis huxleyi" is currently the smallest non-avialan dinosaur described from a... | https://en.wikipedia.org/wiki?curid=8311 |
4,359 | Many modern birds are highly social, often found living in flocks. There is general agreement that some behaviors that are common in birds, as well as in crocodiles (closest living relatives of birds), were also common among extinct dinosaur groups. Interpretations of behavior in fossil species are generally based on t... | https://en.wikipedia.org/wiki?curid=8311 |
4,360 | The first potential evidence for herding or flocking as a widespread behavior common to many dinosaur groups in addition to birds was the 1878 discovery of 31 "Iguanodon", ornithischians that were then thought to have perished together in Bernissart, Belgium, after they fell into a deep, flooded sinkhole and drowned. O... | https://en.wikipedia.org/wiki?curid=8311 |
4,361 | The crests and frills of some dinosaurs, like the marginocephalians, theropods and lambeosaurines, may have been too fragile to be used for active defense, and so they were likely used for sexual or aggressive displays, though little is known about dinosaur mating and territorialism. Head wounds from bites suggest that... | https://en.wikipedia.org/wiki?curid=8311 |
4,362 | From a behavioral standpoint, one of the most valuable dinosaur fossils was discovered in the Gobi Desert in 1971. It included a "Velociraptor" attacking a "Protoceratops", providing evidence that dinosaurs did indeed attack each other. Additional evidence for attacking live prey is the partially healed tail of an "Edm... | https://en.wikipedia.org/wiki?curid=8311 |
4,363 | Comparisons between the scleral rings of dinosaurs and modern birds and reptiles have been used to infer daily activity patterns of dinosaurs. Although it has been suggested that most dinosaurs were active during the day, these comparisons have shown that small predatory dinosaurs such as dromaeosaurids, "Juravenator",... | https://en.wikipedia.org/wiki?curid=8311 |
4,364 | Based on fossil evidence from dinosaurs such as "Oryctodromeus", some ornithischian species seem to have led a partially fossorial (burrowing) lifestyle. Many modern birds are arboreal (tree climbing), and this was also true of many Mesozoic birds, especially the enantiornithines. While some early bird-like species may... | https://en.wikipedia.org/wiki?curid=8311 |
4,365 | Modern birds are known to communicate using visual and auditory signals, and the wide diversity of visual display structures among fossil dinosaur groups, such as horns, frills, crests, sails, and feathers, suggests that visual communication has always been important in dinosaur biology. Reconstruction of the plumage c... | https://en.wikipedia.org/wiki?curid=8311 |
4,366 | The earliest remains of a syrinx, which has enough mineral content for fossilization, was found in a specimen of the duck-like "Vegavis iaai" dated 69 –66 million years ago, and this organ is unlikely to have existed in non-avian dinosaurs. However, in contrast to Senter, other researchers have suggested that dinosaurs... | https://en.wikipedia.org/wiki?curid=8311 |
4,367 | All dinosaurs laid amniotic eggs. Dinosaur eggs were usually laid in a nest. Most species create somewhat elaborate nests which can be cups, domes, plates, beds scrapes, mounds, or burrows. Some species of modern bird have no nests; the cliff-nesting common guillemot lays its eggs on bare rock, and male emperor penguin... | https://en.wikipedia.org/wiki?curid=8311 |
4,368 | When laying eggs, females grow a special type of bone between the hard outer bone and the marrow of their limbs. This medullary bone, which is rich in calcium, is used to make eggshells. A discovery of features in a "Tyrannosaurus" skeleton provided evidence of medullary bone in extinct dinosaurs and, for the first tim... | https://en.wikipedia.org/wiki?curid=8311 |
4,369 | Another widespread trait among modern birds (but see below in regards to fossil groups and extant megapodes) is parental care for young after hatching. Jack Horner's 1978 discovery of a "Maiasaura" ("good mother lizard") nesting ground in Montana demonstrated that parental care continued long after birth among ornithop... | https://en.wikipedia.org/wiki?curid=8311 |
4,370 | However, there is ample evidence of precociality or superprecociality among many dinosaur species, particularly theropods. For instance, non-ornithuromorph birds have been abundantly demonstrated to have had slow growth rates, megapode-like egg burying behavior and the ability to fly soon after birth. Both "Tyrannosaur... | https://en.wikipedia.org/wiki?curid=8311 |
4,371 | Genital structures are unlikely to fossilize as they lack scales that may allow preservation via pigmentation or residual calcium phosphate salts. In 2021, the best preserved specimen of a dinosaur's cloacal vent exterior was described for "Psittacosaurus", demonstrating lateral swellings similar to crocodylian musk gl... | https://en.wikipedia.org/wiki?curid=8311 |
4,372 | Because both modern crocodilians and birds have four-chambered hearts (albeit modified in crocodilians), it is likely that this is a trait shared by all archosaurs, including all dinosaurs. While all modern birds have high metabolisms and are endothermic ("warm-blooded"), a vigorous debate has been ongoing since the 19... | https://en.wikipedia.org/wiki?curid=8311 |
4,373 | After non-avian dinosaurs were discovered, paleontologists first posited that they were ectothermic. This was used to imply that the ancient dinosaurs were relatively slow, sluggish organisms, even though many modern reptiles are fast and light-footed despite relying on external sources of heat to regulate their body t... | https://en.wikipedia.org/wiki?curid=8311 |
4,374 | One of the greatest contributions to the modern understanding of dinosaur physiology has been paleohistology, the study of microscopic tissue structure in dinosaurs. From the 1960s forward, Armand de Ricqlès suggested that the presence of fibrolamellar bone—bony tissue with an irregular, fibrous texture and filled with... | https://en.wikipedia.org/wiki?curid=8311 |
4,375 | In saurischian dinosaurs, higher metabolisms were supported by the evolution of the avian respiratory system, characterized by an extensive system of air sacs that extended the lungs and invaded many of the bones in the skeleton, making them hollow. Such respiratory systems, which may have appeared in the earliest saur... | https://en.wikipedia.org/wiki?curid=8311 |
4,376 | Like other reptiles, dinosaurs are primarily uricotelic, that is, their kidneys extract nitrogenous wastes from their bloodstream and excrete it as uric acid instead of urea or ammonia via the ureters into the intestine. This would have helped them to conserve water. In most living species, uric acid is excreted along ... | https://en.wikipedia.org/wiki?curid=8311 |
4,377 | The size and shape of the brain can be partly reconstructed based on the surrounding bones. In 1896, Marsh calculated ratios between brain weight and body weight of seven species of dinosaurs, showing that the brain of dinosaurs was proportionally smaller than in today's crocodiles, and that the brain of "Stegosaurus" ... | https://en.wikipedia.org/wiki?curid=8311 |
4,378 | The possibility that dinosaurs were the ancestors of birds was first suggested in 1868 by Thomas Henry Huxley. After the work of Gerhard Heilmann in the early 20th century, the theory of birds as dinosaur descendants was abandoned in favor of the idea of them being descendants of generalized thecodonts, with the key pi... | https://en.wikipedia.org/wiki?curid=8311 |
4,379 | Feathers are one of the most recognizable characteristics of modern birds, and a trait that was also shared by several non-avian dinosaurs. Based on the current distribution of fossil evidence, it appears that feathers were an ancestral dinosaurian trait, though one that may have been selectively lost in some species. ... | https://en.wikipedia.org/wiki?curid=8311 |
4,380 | "Archaeopteryx" was the first fossil found that revealed a potential connection between dinosaurs and birds. It is considered a transitional fossil, in that it displays features of both groups. Brought to light just two years after Charles Darwin's seminal "On the Origin of Species" (1859), its discovery spurred the na... | https://en.wikipedia.org/wiki?curid=8311 |
4,381 | The description of feathered dinosaurs has not been without controversy; perhaps the most vocal critics have been Alan Feduccia and Theagarten Lingham-Soliar, who have proposed that some purported feather-like fossils are the result of the decomposition of collagenous fiber that underlaid the dinosaurs' skin, and that ... | https://en.wikipedia.org/wiki?curid=8311 |
4,382 | Because feathers are often associated with birds, feathered dinosaurs are often touted as the missing link between birds and dinosaurs. However, the multiple skeletal features also shared by the two groups represent another important line of evidence for paleontologists. Areas of the skeleton with important similaritie... | https://en.wikipedia.org/wiki?curid=8311 |
4,383 | Large meat-eating dinosaurs had a complex system of air sacs similar to those found in modern birds, according to a 2005 investigation led by Patrick M. O'Connor. The lungs of theropod dinosaurs (carnivores that walked on two legs and had bird-like feet) likely pumped air into hollow sacs in their skeletons, as is the ... | https://en.wikipedia.org/wiki?curid=8311 |
4,384 | Fossils of the troodonts "Mei" and "Sinornithoides" demonstrate that some dinosaurs slept with their heads tucked under their arms. This behavior, which may have helped to keep the head warm, is also characteristic of modern birds. Several deinonychosaur and oviraptorosaur specimens have also been found preserved on to... | https://en.wikipedia.org/wiki?curid=8311 |
4,385 | Some dinosaurs are known to have used gizzard stones like modern birds. These stones are swallowed by animals to aid digestion and break down food and hard fibers once they enter the stomach. When found in association with fossils, gizzard stones are called gastroliths. | https://en.wikipedia.org/wiki?curid=8311 |
4,386 | All non-avian dinosaurs and most lineages of birds became extinct in a mass extinction event, called the Cretaceous–Paleogene (K-Pg) extinction event, at the end of the Cretaceous period. Above the Cretaceous–Paleogene boundary, which has been dated to 66.038 ± 0.025 million years ago, fossils of non-avian dinosaurs di... | https://en.wikipedia.org/wiki?curid=8311 |
4,387 | Just before the K-Pg extinction event, the number of non-avian dinosaur species that existed globally has been estimated at between 628 and 1078. It remains uncertain whether the diversity of dinosaurs was in gradual decline before the K-Pg extinction event, or whether dinosaurs were actually thriving prior to the exti... | https://en.wikipedia.org/wiki?curid=8311 |
4,388 | The bolide impact hypothesis, first brought to wide attention in 1980 by Walter Alvarez, Luis Alvarez, and colleagues, attributes the K-Pg extinction event to a bolide (extraterrestrial projectile) impact. Alvarez and colleagues proposed that a sudden increase in iridium levels, recorded around the world in rock deposi... | https://en.wikipedia.org/wiki?curid=8311 |
4,389 | Within hours, the Chicxulub impact would have created immediate effects such as earthquakes, tsunamis, and a global firestorm that likely killed unsheltered animals and started wildfires. However, it would also have had longer-term consequences for the environment. Within days, sulphate aerosols released from rocks at ... | https://en.wikipedia.org/wiki?curid=8311 |
4,390 | At the time of the K-Pg extinction, the Deccan Traps flood basalts of India were actively erupting. The eruptions can be separated into three phases around the K-Pg boundary, two prior to the boundary and one after. The second phase, which occurred very close to the boundary, would have extruded 70 to 80% of the volume... | https://en.wikipedia.org/wiki?curid=8311 |
4,391 | Before 2000, arguments that the Deccan Traps eruptions—as opposed to the Chicxulub impact—caused the extinction were usually linked to the view that the extinction was gradual. Prior to the discovery of the Chicxulub crater, the Deccan Traps were used to explain the global iridium layer; even after the crater's discove... | https://en.wikipedia.org/wiki?curid=8311 |
4,392 | Whether the Deccan Traps were a major cause of the extinction, on par with the Chicxulub impact, remains uncertain. Proponents consider the climatic impact of the sulphur dioxide released to have been on par with the Chicxulub impact, and also note the role of flood basalt volcanism in other mass extinctions like the P... | https://en.wikipedia.org/wiki?curid=8311 |
4,393 | Non-avian dinosaur remains have occasionally been found above the K-Pg boundary. In 2000, Spencer Lucas and colleagues reported the discovery of a single hadrosaur right femur in the San Juan Basin of New Mexico, and described it as evidence of Paleocene dinosaurs. The rock unit in which the bone was discovered has bee... | https://en.wikipedia.org/wiki?curid=8311 |
4,394 | By human standards, dinosaurs were creatures of fantastic appearance and often enormous size. As such, they have captured the popular imagination and become an enduring part of human culture. The entry of the word "dinosaur" into the common vernacular reflects the animals' cultural importance: in English, "dinosaur" is... | https://en.wikipedia.org/wiki?curid=8311 |
4,395 | Public enthusiasm for dinosaurs first developed in Victorian England, where in 1854, three decades after the first scientific descriptions of dinosaur remains, a menagerie of lifelike dinosaur sculptures was unveiled in London's Crystal Palace Park. The Crystal Palace dinosaurs proved so popular that a strong market in... | https://en.wikipedia.org/wiki?curid=8311 |
4,396 | The popular preoccupation with dinosaurs has ensured their appearance in literature, film, and other media. Beginning in 1852 with a passing mention in Charles Dickens "Bleak House", dinosaurs have been featured in large numbers of fictional works. Jules Verne's 1864 novel "Journey to the Center of the Earth", Sir Arth... | https://en.wikipedia.org/wiki?curid=8311 |
4,397 | Neil Alden Armstrong (August 5, 1930 – August 25, 2012) was an American astronaut and aeronautical engineer who became the first person to walk on the Moon in 1969. He was also a naval aviator, test pilot, and university professor. | https://en.wikipedia.org/wiki?curid=21247 |
4,398 | Armstrong was born and raised in Wapakoneta, Ohio. A graduate of Purdue University, he studied aeronautical engineering; his college tuition was paid for by the U.S. Navy under the Holloway Plan. He became a midshipman in 1949 and a naval aviator the following year. He saw action in the Korean War, flying the Grumman F... | https://en.wikipedia.org/wiki?curid=21247 |
4,399 | Armstrong joined the NASA Astronaut Corps in the second group, which was selected in 1962. He made his first spaceflight as command pilot of Gemini 8 in March 1966, becoming NASA's first civilian astronaut to fly in space. During this mission with pilot David Scott, he performed the first docking of two spacecraft; the... | https://en.wikipedia.org/wiki?curid=21247 |
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