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123-400: The Dinosaur Park Formation contains dense concentrations of dinosaur skeletons, both articulated and disarticulated, which are often found with preserved remains of soft tissues. Remains of other animals such as fish , turtles , and crocodilians , as well as plant remains, are also abundant. The formation has been named after Dinosaur Provincial Park , a UNESCO World Heritage Site where

246-607: A gazetteer compiled by Chang Qu  ( 常璩 ) during the Western Jin Dynasty (265–316), reported the discovery of dragon bones at Wucheng in Sichuan Province. Villagers in central China have long unearthed fossilized "dragon bones" for use in traditional medicines . In Europe , dinosaur fossils were generally believed to be the remains of giants and other biblical creatures. Scholarly descriptions of what would now be recognized as dinosaur bones first appeared in

369-510: A sacrum composed of three or more fused vertebrae (three are found in some other archosaurs, but only two are found in Herrerasaurus ); and a perforate acetabulum , or hip socket, with a hole at the center of its inside surface (closed in Saturnalia tupiniquim , for example). Another difficulty of determining distinctly dinosaurian features is that early dinosaurs and other archosaurs from

492-421: A "pillar-erect" configuration of the hip joint, where instead of having a projection from the femur insert on a socket on the hip, the upper pelvic bone was rotated to form an overhanging shelf. 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  ( 華陽國志 ),

615-488: A controversial taxon that was recently confirmed to exist after archived photos were uncovered. Bruhathkayosaurus was a titanosaur and would have most likely weighed more than even Marrapunisaurus . Recent size estimates in 2023 have placed this sauropod reaching lengths of up to 44 m (144 ft) long and a colossal weight range of around 110 000 – 170 000  kg ( 240 000 – 370 000  lb), if these upper estimates up true, Bruhathkayosaurus would have rivaled

738-448: A corresponding inwardly facing distinct head on the femur. Their erect posture enabled early dinosaurs to breathe easily while moving, which likely permitted stamina and activity levels that surpassed those of "sprawling" reptiles . Erect limbs probably also helped support the evolution of large size by reducing bending stresses on limbs. Some non-dinosaurian archosaurs, including rauisuchians , also had erect limbs but achieved this by

861-632: A dinosaur. In it he described and named a sauropod tooth , " Rutellum impicatum ", that had been found in Caswell, near Witney , Oxfordshire. 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 ,

984-537: A femur of Tyrannosaurus preserved soft, flexible tissue within, including blood vessels , bone matrix , and connective tissue (bone fibers) that had retained their microscopic structure. This discovery suggested that original soft tissues could be preserved over geological time, with multiple mechanisms having been proposed. Later, in 2009, Schweitzer and colleagues reported that a Brachylophosaurus femur preserved similar microstructures, and immunohistochemical techniques (based on antibody binding) demonstrated

1107-530: A firming agent, a flavor enhancer , a leavening agent , a nutrient supplement, a stabilizer, and thickener. Eggshells are also used as a calcium supplement in orange juice. Eggshells have been incorporated into fertilizers as a soil conditioner . They have also been used as a supplement to animal feed. More recently the egg calcium carbonate particles have been used as coating pigments for ink-jet printing. Powdered eggshells are also used in making paper pulp . Recently eggshell waste has been used as

1230-422: 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. Collectively, dinosaurs as a clade are divided into two primary branches, Saurischia and Ornithischia. Saurischia includes those taxa sharing

1353-591: A low cost catalyst for biodiesel production. Chicken eggshells have been additionally incorporated as a calcium precursor into the synthesis of calcium-based metal-organic frameworks (MOFs). Recently, researchers have utilized chicken eggshells as a biofiller with a conducting polymer to enhance its sensing properties. Typically, eggshells were used as biofiller in polyaniline matrix to detect ammonia gas. The optimum ratio between eggshells and polyaniline could enhance this sensor measurement. Ostrich eggshells have been used by Sub Saharan hunter-gathers. For instance

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1476-482: 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 Saurischia. Anatomically, these two groups can be distinguished most noticeably by their pelvic structure. Early saurischians—"lizard-hipped", from the Greek sauros ( σαῦρος ) meaning "lizard" and ischion ( ἰσχίον ) meaning "hip joint"—retained

1599-583: A now lost partial vertebral neural arch described in 1878. Extrapolating from the illustration of this bone, the animal may have been 58 meters (190 ft) long and weighed 122 400  kg ( 269 800  lb). However, recent research have placed Amphicoelias from the long, gracile diplodocid to the shorter but much stockier rebbachisaurid. Now renamed as Maraapunisaurus , this sauropod now stands as much as 40 meters (130 ft) long and weigh as much as 120 000  kg ( 260 000  lb). Another contender of this title includes Bruhathkayosaurus ,

1722-433: A period of time, with estimates ranging from 5–10 million years to 21 million years. 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 successful than

1845-652: A potential food source, radiated in the Late Triassic. Early sauropodomorphs did not have sophisticated mechanisms for processing food in the mouth, and so must have employed other means of breaking down food farther along the digestive tract. The general homogeneity of dinosaurian faunas continued into the Middle and Late Jurassic, where most localities had predators consisting of ceratosaurians , megalosauroids , and allosauroids , and herbivores consisting of stegosaurian ornithischians and large sauropods. Examples of this include

1968-656: A presentation about fossil reptiles to the British Association for the Advancement of Science in 1841, but reports of the time show that Owen did not mention the word "dinosaur", nor recognize dinosaurs as a distinct group of reptiles in his address. He introduced the Dinosauria only in the revised text version of his talk published in April 1842. With the backing of Prince Albert , the husband of Queen Victoria , Owen established

2091-417: A regular array pattern. The mammillae are proteoglycan-rich and are thought to control calcification. In the shell gland (similar to a mammalian uterus), mineralization starts at the mammillae and around the outermost membrane fibers. The shell gland fluid contains very high levels of calcium and bicarbonate ions . The thick calcified layer of the eggshell forms in columns from the mammillae structures, and

2214-599: A review paper by Paul Sereno in 1998, were accompanied by increases in the number of published phylogenetic trees for dinosaurs. Dinosaur fossils are not limited to bones, but also include imprints or mineralized remains of skin coverings, organs, and other tissues. Of these, skin coverings based on keratin proteins are most easily preserved because of their cross-linked , hydrophobic molecular structure. Fossils of keratin-based skin coverings or bony skin coverings are known from most major groups of dinosaurs. Dinosaur fossils with scaly skin impressions have been found since

2337-549: A series of studies that likewise argued for active lifestyles in dinosaurs based on anatomical and ecological evidence (see § Physiology ), which were subsequently summarized in his 1986 book The Dinosaur Heresies . New revelations were supported by an increase in dinosaur discoveries. Major new dinosaur discoveries have been made by paleontologists working in previously unexplored regions, including India, South America, Madagascar, Antarctica, and most significantly China. Across theropods, sauropodomorphs, and ornithischians,

2460-659: A single day. The most common remains of young hadrosaurs in the Dinosaur Park Formation are dentaries , bones from limbs and feet, as well as vertebral centra . The material showed little or none of the abrasion that would have resulted from transport, meaning the fossils were buried near their point of origin. Bonebeds 23, 28, 47, and 50 are productive sources of young hadrosaur remains in the formation, especially bonebed 50. The bones of juvenile hadrosaurs and fossil eggshell fragments are not known to have preserved in association with each other, despite both being present in

2583-603: A sister group to Dinosauria, including a large anterior trochanter, metatarsals II and IV of subequal length, reduced contact between ischium and pubis, the presence of a cnemial crest on the tibia and of an ascending process on the astragalus, and many others. A variety of other skeletal features are shared by dinosaurs. However, because they either are 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 (openings in

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2706-421: A synthesis presented by Fowler (2017) with additional information from Arbour et al. 2009, Evans et al. 2009, and Penkalski, 2013. Megaherbivore Assemblage Zones (MAZ) follow data presented by Mallon et al. , 2012. Remains of the following amphibians have been found in the formation: Albanerpetontidae (extinct, salamander -like amphibians) Caudata ( salamanders ) Salientia ( frogs ) Remains of

2829-490: A two layered structure: an external vitellin layer made of chitin that confers mechanical resistance and an internal lipid-rich layer that makes the egg chamber impermeable. Insects and other arthropods lay a large variety of styles and shapes of eggs. Some of them have gelatinous or skin-like coverings, others have hard eggshells. Softer shells are mostly protein. It may be fibrous or quite liquid. Some arthropod eggs do not actually have shells, rather, their outer covering

2952-490: 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 some later groups of dinosaurs featured further modified versions of these traits, they are considered typical for Dinosauria; the earliest dinosaurs had them and passed them on to their descendants. Such modifications, originating in

3075-463: 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 enantiornithines , aquatic hesperornithines , and even the larger terrestrial theropods (in the form of Gastornis , eogruiids , bathornithids , ratites, geranoidids , mihirungs , and " terror birds "). It

3198-430: Is 39.7 meters (130 ft) long. 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 80 000 to 100 000 kilograms (88 to 110 short tons) and reached lengths of 30 to 40 meters (98 to 131 ft); some of

3321-699: Is a synapsid ). None of them had the erect hind limb posture characteristic of true dinosaurs. 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. Dinosaurs have always been recognized as an extremely varied group: over 900 non-avian dinosaur genera have been confidently identified (2018) with 1124 species (2016). Estimates put

3444-511: Is actually the outermost embryonic membrane, the choroid, which protects inner layers. This can be a complex structure, and it may have different layers, including an outermost layer called an exochorion. Eggs which must survive in dry conditions usually have hard eggshells, made mostly of dehydrated or mineralized proteins with pore systems to allow respiration . Arthropod eggs can have extensive ornamentation on their outer surfaces. Fish and amphibians generally lay eggs which are surrounded by

3567-465: Is an inexact art, and reconstructing the muscles and other organs of the living animal is, at best, a process of educated guesswork. 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

3690-755: Is based in part on preservation bias , as large, sturdy bones are more likely to last until they are fossilized. Many dinosaurs were quite small, some measuring about 50 centimeters (20 inches) in length. 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 1842 to refer to these "great fossil lizards". Since then, mounted fossil dinosaur skeletons have been major attractions at museums worldwide, and dinosaurs have become an enduring part of popular culture . The large sizes of some dinosaurs, as well as their seemingly monstrous and fantastic nature, have ensured their regular appearance in best-selling books and films, such as

3813-459: Is between 1 and 10 metric tons (1.1 and 11.0 short tons). This contrasts sharply with the average size of Cenozoic mammals, estimated by the National Museum of Natural History as about 2 to 5 kg (4.4 to 11.0 lb). 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

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3936-433: Is deposited on the egg in layers within the uterus. The egg can take up fluids and grow in size during this process, and the final, most rigid layer is not added until the egg is full-size. Hatching birds, amphibian and egg-laying reptiles have an egg-tooth used to start an exit hole in the hard eggshell. Eggshell waste is fundamentally composed of calcium carbonate , and has the potential to be used as raw material in

4059-617: 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 biomechanics ), chemistry , biology , and the Earth sciences (of which paleontology is a sub-discipline). Two topics of particular interest and study have been dinosaur size and behavior. Current evidence suggests that dinosaur average size varied through

4182-432: Is known as the palisade layer. Between these palisade columns are narrow pores that traverse the eggshell and allow gaseous exchange. The cuticle forms the final, outer layer of the eggshell. Attachment of the soft organic fibrous membrane to the hard calcite shell is essential for proper chick embryonic development and growth (via ensuring association of the chorioallantoic membrane, and in allowing for air-sac formation at

4305-472: Is not a coincidence as the invertebrate shells would have slowly dissolved and released enough basic calcium carbonate to protect the eggshells from naturally occurring acids that otherwise would have dissolved them and prevented fossilization. In contrast with eggshell fossils, the remains of very young hadrosaurs are actually somewhat common. Darren Tanke has observed that an experienced collector could actually discover multiple juvenile hadrosaur specimens in

4428-570: Is now at the American Museum of Natural History in New York City, while Marsh's is at the Peabody Museum of Natural History at Yale University . World War II caused a pause in palaeontological research; after the war, research attention was also diverted increasingly to fossil mammals rather than dinosaurs, which were seen as sluggish and cold-blooded. At the end of the 1960s, however,

4551-644: Is often stated that mammals out-competed the neornithines for dominance of most terrestrial niches but many of these groups co-existed with rich mammalian faunas for most of the Cenozoic Era. Terror birds and bathornithids occupied carnivorous guilds alongside predatory mammals, and ratites are still fairly successful as midsized herbivores; eogruiids similarly lasted from the Eocene to Pliocene , becoming extinct only very recently after over 20 million years of co-existence with many mammal groups. Dinosaurs belong to

4674-596: Is subjected to most pressure during its passage and consequently shows the most color. As they contain mainly calcium carbonate , bird eggshells dissolve in various acids, including the vinegar used in cooking. While dissolving, the calcium carbonate in an eggshell reacts with the acid to form carbon dioxide . The US food industry generates 150,000 tons of shell waste per year. The disposal methods for waste eggshells are 26.6% as fertilizer, 21.1% as animal feed ingredients, 26.3% discarded in municipal dumps, and 15.8% used in other ways. Many landfills are unwilling to take

4797-528: The Jurassic Park franchise. Persistent public enthusiasm for the animals has resulted in significant funding for dinosaur science, and new discoveries are regularly covered by the media. 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

4920-437: The blue whale and Perucetus colossus as one of the largest animals to have ever existed. The largest carnivorous dinosaur was Spinosaurus , reaching a length of 12.6 to 18 meters (41 to 59 ft) and weighing 7 to 20.9 metric tons (7.7 to 23.0 short tons). Other large carnivorous theropods included Giganotosaurus , Carcharodontosaurus , and Tyrannosaurus . Therizinosaurus and Deinocheirus were among

5043-666: The Anisian epoch of the Triassic, approximately 243 million years ago, which is the age of Nyasasaurus from the Manda Formation of Tanzania. However, its known fossils are too fragmentary to identify it as a dinosaur or only a close relative. The referral of the Manda Formation to the Anisian is also uncertain. Regardless, dinosaurs existed alongside non-dinosaurian ornithodirans for

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5166-457: The Carnian pluvial event . 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 herbivores. Gymnosperm plants (particularly conifers ),

5289-613: The Ischigualasto and Santa Maria Formations of Argentina and Brazil, and the Pebbly Arkose Formation of Zimbabwe. The Ischigualasto Formation ( radiometrically dated at 231–230 million years old ) has produced the early saurischian Eoraptor , originally considered a member of the Herrerasauridae but now considered to be an early sauropodomorph, along with the herrerasaurids Herrerasaurus and Sanjuansaurus , and

5412-484: The Late Triassic epoch are often poorly known and were similar in many ways; these animals have sometimes been misidentified in the literature. 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

5535-645: The Morrison Formation of North America and Tendaguru Beds of Tanzania. Dinosaurs in China show some differences, with specialized metriacanthosaurid theropods and unusual, long-necked sauropods like Mamenchisaurus . Ankylosaurians and ornithopods were also becoming more common, but primitive sauropodomorphs had become extinct. Conifers and pteridophytes were the most common plants. Sauropods, like earlier sauropodomorphs, were not oral processors, but ornithischians were evolving various means of dealing with food in

5658-487: The Natural History Museum, London , to display the national collection of dinosaur fossils and other biological and geological exhibits. 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

5781-621: The Oldman Formation and Judith River Formation Potentially synonymous with Stegoceras validum . Sphaerotholus S. lyonsi Upper, 76.10 ± 0.5 Ma Right squamosal Stegoceras S. validum Specimens including frontoparietal dome. " Microcephale " A nomen nudum . In the Dinosaur Park Formation, small theropods are rare due to the tendency of their thin-walled bones to be broken or poorly preserved. Small bones of small theropods that were preyed upon by larger ones may have been swallowed whole and digested. In this context,

5904-611: The Pietraroja Plattenkalk of Italy. It preserves portions of the intestines, colon, liver, muscles, and windpipe. Concurrently, a line of work led by Mary Higby Schweitzer , Jack Horner , and colleagues reported various occurrences of preserved soft tissues and proteins within dinosaur bone fossils. Various mineralized structures that likely represented red blood cells and collagen fibres had been found by Schweitzer and others in tyrannosaurid bones as early as 1991. However, in 2005, Schweitzer and colleagues reported that

6027-676: The United States and displayed in Pittsburgh 's Carnegie Museum of Natural History in 1907. The longest dinosaur known from good fossil material is Patagotitan : the skeleton mount in the American Museum of Natural History in New York is 37 meters (121 ft) long. The Museo Municipal Carmen Funes in Plaza Huincul , Argentina, has an Argentinosaurus reconstructed skeleton mount that

6150-427: 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 non-avian dinosaur specimens that are recovered are complete skeletons, and impressions of skin and other soft tissues are rare. Rebuilding a complete skeleton by comparing the size and morphology of bones to those of similar, better-known species

6273-530: The "lizard-hipped" dinosaurs—birds evolved from earlier dinosaurs with "lizard hips". 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. Timeline of major dinosaur groups per Holtz (2007) . Knowledge about dinosaurs

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6396-409: The 19th century. Samuel Beckles discovered a sauropod forelimb with preserved skin in 1852 that was incorrectly attributed to a crocodile; it was correctly attributed by Marsh in 1888 and subject to further study by Reginald Hooley in 1917. Among ornithischians, in 1884 Jacob Wortman found skin impressions on the first known specimen of Edmontosaurus annectens , which were largely destroyed during

6519-614: The Dinosaur Park Formation. This eggshell is similar to the hadrosaur eggshell of Devil's Coulee in southern Alberta as well as that of the Two Medicine and Judith River Formations in Montana, United States. While present, dinosaur eggshell is very rare in the Dinosaur Park Formation and is only found in two different microfossil sites. These sites are distinguished by large numbers of pisidiid clams and other less common shelled invertebrates like unionid clams and snails. This association

6642-501: 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 around the world. The term is derived from Ancient Greek δεινός (deinos)  'terrible, potent or fearfully great' and σαῦρος (sauros)  'lizard or reptile'. Though

6765-577: 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 additional forward-pointing process. Ornithischia includes a variety of species that were primarily herbivores. Despite the terms "bird hip" (Ornithischia) and "lizard hip" (Saurischia), birds are not part of Ornithischia. Birds instead belong to Saurischia,

6888-501: The Late Cretaceous, was the evolution of flowering plants . At the same time, several groups of dinosaurian herbivores evolved more sophisticated ways to orally process food. Ceratopsians developed a method of slicing with teeth stacked on each other in batteries, and iguanodontians refined a method of grinding with dental batteries , taken to its extreme in hadrosaurids. Some sauropods also evolved tooth batteries, best exemplified by

7011-781: The MRCA of Megalosaurus and Iguanodon , because these were two of the three genera cited by Richard Owen when he recognized the Dinosauria. Both definitions cover the same known genera: Dinosauria = Ornithischia + Saurischia . This includes major groups such as ankylosaurians (armored herbivorous quadrupeds), stegosaurians (plated herbivorous quadrupeds), ceratopsians (bipedal or quadrupedal herbivores with neck frills ), pachycephalosaurians (bipedal herbivores with thick skulls), ornithopods (bipedal or quadrupedal herbivores including " duck-bills "), theropods (mostly bipedal carnivores and birds), and sauropodomorphs (mostly large herbivorous quadrupeds with long necks and tails). Birds are

7134-401: 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. The oldest dinosaur fossils known from substantial remains date to the Carnian epoch of the Triassic period and have been found primarily in

7257-545: The Oldman Formation but abundant in the Dinosaur Park Formation. The Dinosaur Park Formation can be divided into at least two distinct faunas. The lower part of the formation is characterized by the abundance of Corythosaurus and Centrosaurus . This group of species is replaced higher in the formation by a different ornithischian fauna characterized by the presence of Lambeosaurus and Styracosaurus . The appearance of several new, rare species of ornithischian at

7380-519: 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 100-to-1,000 kg (220-to-2,200 lb) category when sorted by estimated weight into categories based on order of magnitude , whereas recent predatory carnivoran mammals peak in the 10-to-100 kg (22-to-220 lb) category. The mode of Mesozoic dinosaur body masses

7503-583: The United States, known as dinosaur mania. 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 entire fortune on the dinosaur hunt. Many valuable dinosaur specimens were damaged or destroyed due to

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7626-773: The adjacent coastal plain, depositing the marine shales of the Bearpaw Formation on top of the Dinosaur Park Formation. The Dinosaur Park Formation is about 70 metres (230 ft) thick at Dinosaur Park. The lower portion of the formation was laid down in fluvial channel environments and consists primarily of fine- to medium-grained, crossbedded sandstones . The upper portion, which was deposited in overbank and floodplain environments, consists primarily of massive to laminated, organic-rich mudstones with abundant root traces, and thin beds of bentonite . The Lethbridge Coal Zone, which consists of several seams of low-rank coal interbedded with mudstones and siltstones , marks

7749-571: The ancient upland and lowlands of the formation's depositional environment. The upland nesting grounds may have been preferred by the less common hadrosaurs, like Brachylophosaurus or Parasaurolophus . However, the authors were unable to determine what specific factors shaped nesting ground choice in the formation's hadrosaurs. They suggested that behavior, diet, soil condition, and competition between dinosaur species all potentially influenced where hadrosaurs nested. Sub-centimeter fragments of pebbly-textured hadrosaur eggshell have been reported from

7872-666: The best-known genera are remarkable for their large size, many Mesozoic dinosaurs were human-sized or smaller, and modern birds are generally small in size. Dinosaurs today inhabit every continent, and fossils show that they had achieved global distribution by the Early Jurassic epoch at latest. Modern birds inhabit most available habitats, from terrestrial to marine, and there is evidence that some non-avian dinosaurs (such as Microraptor ) could fly or at least glide, and others, such as spinosaurids , had semiaquatic habits. While recent discoveries have made it more difficult to present

7995-474: The blunt end of the egg). This attachment between dissimilar materials is facilitated by a structural interdigitation of fibers into each mammillae at the microscale, and reciprocally, at the nanoscale, mineral spiking into fibers directly at the interface While the bulk of eggshell is made of calcium carbonate, it is now thought that the protein matrix has an important role to play in eggshell strength. These proteins affect crystallization, which in turn affects

8118-455: The body . Other prehistoric animals, including pterosaurs , mosasaurs , ichthyosaurs , plesiosaurs , and Dimetrodon , while often popularly conceived of as dinosaurs, are not taxonomically classified as dinosaurs. Pterosaurs are distantly related to dinosaurs, being members of the clade Ornithodira . The other groups mentioned are, like dinosaurs and pterosaurs, members of Sauropsida (the reptile and bird clade), except Dimetrodon (which

8241-429: The bone as the lower extremity of the femur of a large animal, and recognized that it was too large to belong to any known species. He therefore concluded it to be the femur of a huge human, perhaps a Titan or another type of giant featured in legends. Edward Lhuyd , a friend of Sir Isaac Newton , published Lithophylacii Britannici ichnographia (1699), the first scientific treatment of what would now be recognized as

8364-467: The common theropods, and ankylosaurids and early ceratopsians like Psittacosaurus became important herbivores. Meanwhile, Australia was home to a fauna of basal ankylosaurians, hypsilophodonts , and iguanodontians. The stegosaurians appear to have gone extinct at some point in the late Early Cretaceous or early Late Cretaceous . A major change in the Early Cretaceous, which would be amplified in

8487-713: The dinosaur subgroup Maniraptora , which are coelurosaurs , which are theropods, which are saurischians. 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 sauropodomorphs. This would cause sauropods and kin to fall outside traditional dinosaurs, so they re-defined Dinosauria as

8610-427: The dinosaurs' modern-day surviving avian lineage (birds) are generally small due to the constraints of flight, many prehistoric dinosaurs (non-avian and avian) were large-bodied—the largest sauropod dinosaurs are estimated to have reached lengths of 39.7 meters (130 feet) and heights of 18 m (59 ft) and were the largest land animals of all time. The misconception that non-avian dinosaurs were uniformly gigantic

8733-686: The dinosaurs. Most of these other animals became extinct in the Triassic, in one of two events. First, at about 215 million years ago, a variety of basal archosauromorphs, including the protorosaurs , became extinct. This was followed by the Triassic–Jurassic extinction event (about 201 million years ago), that saw the end of most of the other groups of early archosaurs, like aetosaurs, ornithosuchids, phytosaurs , and rauisuchians. Rhynchosaurs and dicynodonts survived (at least in some areas) at least as late as early –mid Norian and late Norian or earliest Rhaetian stages , respectively, and

8856-434: The discovery of a small theropod dinosaur with preserved tooth marks was especially valuable. Possible indeterminate avimimid remains are known from the formation. A new taxon of troodontid based solely on teeth is known from the upper part of the formation. Choristoderes , or champsosaurs , were aquatic reptiles. Small examples looked like lizards, while larger types were superficially similar to crocodilians. Remains of

8979-748: The dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya and their dominance continued throughout the Jurassic and Cretaceous periods. The fossil record shows that birds are feathered dinosaurs , having evolved from earlier theropods during the Late Jurassic epoch , and are the only dinosaur lineage known to have survived the Cretaceous–Paleogene extinction event approximately 66 mya. Dinosaurs can therefore be divided into avian dinosaurs —birds—and

9102-574: The early saurischian Alwalkeria , are known from the Upper Maleri and Lower Maleri Formations of India. The Carnian-aged Chañares Formation of Argentina preserves primitive, dinosaur-like ornithodirans such as Lagosuchus and Lagerpeton in Argentina , making it another important site for understanding dinosaur evolution. These ornithodirans support the model of early dinosaurs as small, bipedal predators. Dinosaurs may have appeared as early as

9225-416: The eggshell structure. The concentration of eggshell proteins decreases over the life of the laying hen, as does eggshell strength. In an average laying hen , the process of shell formation takes around 20 hours. Pigmentation is added to the shell by papillae lining the oviduct, coloring it any of a variety of colors and patterns depending on species. Since eggs are usually laid blunt end first, that end

9348-640: The eggshell. The chicken eggshell is 95 -97% calcium carbonate crystals, which are stabilized by a protein matrix. Without the protein, the crystal structure would be too brittle to keep its form and the organic matrix is thought to have a role in deposition of calcium during the mineralization process. The structure and composition of the avian eggshell protects the egg from damage and microbial contamination, prevents desiccation, regulates embryonic gas and water exchange and provides calcium for embryogenesis . Eggshell formation requires gram amounts of calcium being deposited within hours, which must be supplied via

9471-456: 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 , and choristoderans , also survived the event. The surviving lineages of neornithine birds, including the ancestors of modern ratites , ducks and chickens , and

9594-451: The exact date of their extinction is uncertain. These losses left behind a land fauna of crocodylomorphs , dinosaurs, mammals, pterosaurians, and turtles . The first few lines of early dinosaurs diversified through the Carnian and Norian stages of the Triassic, possibly by occupying the niches of the groups that became extinct. Also notably, there was a heightened rate of extinction during

9717-505: The extinct non-avian dinosaurs , which are all dinosaurs other than birds. Dinosaurs are varied from taxonomic , morphological and ecological standpoints. Birds, at over 11,000 living species , are among the most diverse groups of vertebrates. Using fossil evidence, paleontologists have identified over 900 distinct genera and more than 1,000 different species of non-avian dinosaurs. Dinosaurs are represented on every continent by both extant species (birds) and fossil remains. Through

9840-476: The extraembryonic membranes but do not develop a shell, hard or soft, around these membranes. Some fish and amphibian eggs have thick, leathery coats, especially if they must withstand physical force or desiccation. These types of eggs can also be very small and fragile. While many reptiles lay eggs with flexible, calcified eggshells, there are some that lay hard eggs. Eggs laid by snakes generally have leathery shells which often adhere to one another. Depending on

9963-433: The field of dinosaur research experienced a surge in activity that remains ongoing. Several seminal studies led to this activity. First, John Ostrom discovered the bird-like dromaeosaurid theropod Deinonychus and described it in 1969. Its anatomy indicated that it was an active predator that was likely warm-blooded, in marked contrast to the then-prevailing image of dinosaurs. Concurrently, Robert T. Bakker published

10086-478: The first half of the 20th century, before birds were recognized as dinosaurs, most of the scientific community believed dinosaurs to have been sluggish and cold-blooded . Most research conducted since the 1970s , however, has indicated that dinosaurs were active animals with elevated metabolisms and numerous adaptations for social interaction. Some were herbivorous , others carnivorous . Evidence suggests that all dinosaurs were egg-laying , and that nest -building

10209-403: The following Choristoderes have been found in the formation: Remains of the following Crocodylians have been found in the formation: Remains of the following lizards have been found in the formation: Remains of the following Plesiosaurs have been found in the formation: Remains of the following pterosaurs have been found in the formation: Remains of the following turtles have been found in

10332-495: The following dinosaurs have been found in the formation: Remains of the following ornithischians have been found in the formation: An unnamed Pachyrhinosaurus -like taxon has been recovered from the formation. At least one indeterminate thescelosaurid specimen has been recovered from the formation. In a 2001 review of hadrosaur eggshell and hatchling material from the Dinosaur Park Formation, Darren H. Tanke and M. K. Brett-Surman concluded that hadrosaurs nested in both

10455-597: The formation is well exposed in the badlands that flank the Red Deer River . The Dinosaur Park Formation is composed of sediments that were derived from the erosion of the mountains to the west. It was deposited on an alluvial to coastal plain by river systems that flowed eastward and southeastward to the Bearpaw Sea, a large inland sea that was part of the Western Interior Seaway . That sea gradually inundated

10578-495: The formation. Foraminacephale F. brevis Also present in the Oldman Formation Frontoparetal dome, various other skull fragments including juvenile and subadult material Once thought to be a species of Stegoceras [REDACTED] Gravitholus G. albertae "Frontoparietal dome." Potentially synonymous with Stegoceras validum . Hanssuesia H. sternbergi Lower, also present in

10701-454: The formation: Remains of the following mammals have been found in the formation: Dinosaur 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 a subject of active research. They became

10824-401: The hen's diet. The avian eggshell is constructed from an organized assembly of mineral nanoparticles whose size confers different hardness properties to different regions of the shell. The fibrous chicken shell membranes are added in the proximal (white) isthmus of the oviduct . In the distal (red) isthmus mammillae or mammillary knobs are deposited on the surface of the outer membrane in

10947-486: The hip structure of their ancestors, with a pubis bone directed cranially , or forward. This basic form was modified by rotating the pubis backward to varying degrees in several groups ( Herrerasaurus , therizinosauroids, dromaeosaurids, and birds ). Saurischia includes the theropods (exclusively bipedal and with a wide variety of diets) and sauropodomorphs (long-necked herbivores which include advanced, quadrupedal groups). By contrast, ornithischians—"bird-hipped", from

11070-432: The last common ancestor of Triceratops horridus , Passer domesticus and Diplodocus carnegii , and all of its descendants, to ensure that sauropods and kin remain included as dinosaurs. They also resurrected the clade Ornithoscelida to refer to the group containing Ornithischia and Theropoda. Using one of the above definitions, dinosaurs can be generally described as archosaurs with hind limbs held erect beneath

11193-558: 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 Plot , Professor of Chemistry at the University of Oxford and first curator of the Ashmolean Museum , who published a description in his The Natural History of Oxford-shire (1677). He correctly identified

11316-478: The longest were the 33.5-meter (110 ft) long Diplodocus hallorum (formerly Seismosaurus ), the 33-to-34-meter (108 to 112 ft) long Supersaurus , and 37-meter (121 ft) long Patagotitan ; and the tallest, the 18-meter (59 ft) tall Sauroposeidon , which could have reached a sixth-floor window. There were a few dinosaurs that was considered either the heaviest and longest. The most famous one include Amphicoelias fragillimus , known only from

11439-479: The most complete theropod specimens, while North American localities have produced the most complete sauropodomorph specimens. Prior to the dinosaur renaissance, dinosaurs were mostly classified using the traditional rank-based system of Linnaean taxonomy . The renaissance was also accompanied by the increasingly widespread application of cladistics , a more objective method of classification based on ancestry and shared traits, which has proved tremendously useful in

11562-509: The most important advantage was dietary. Large animals are more efficient at digestion than small animals, because food spends more time in their digestive systems. This also permits them to subsist on food with lower nutritive value than smaller animals. Sauropod remains are mostly found in rock formations interpreted as dry or seasonally dry, and the ability to eat large quantities of low-nutrient browse would have been advantageous in such environments. Scientists will probably never be certain of

11685-478: The most recent common ancestor of a certain taxonomic group, are called the synapomorphies of such a group. A detailed assessment of archosaur interrelations by Sterling Nesbitt confirmed or found the following twelve unambiguous synapomorphies, some previously known: 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

11808-458: The mouth, including potential cheek -like organs to keep food in the mouth, and jaw motions to grind food. Another notable evolutionary event of the Jurassic was the appearance of true birds, descended from maniraptoran coelurosaurians. By the Early Cretaceous and the ongoing breakup of Pangaea, dinosaurs were becoming strongly differentiated by landmass. The earliest part of this time saw

11931-764: The now-splitting supercontinent Gondwana , abelisaurids were the common theropods, and titanosaurian sauropods the common herbivores. Finally, in Europe, dromaeosaurids, rhabdodontid iguanodontians, nodosaurid ankylosaurians, and titanosaurian sauropods were prevalent. Flowering plants were greatly radiating, with the first grasses appearing by the end of the Cretaceous. Grinding hadrosaurids and shearing ceratopsians became very diverse across North America and Asia. Theropods were also radiating as herbivores or omnivores , with therizinosaurians and ornithomimosaurians becoming common. The Cretaceous–Paleogene extinction event, which occurred approximately 66 million years ago at

12054-756: The number of named genera began to increase exponentially in the 1990s. As of 2008, over 30 new species of dinosaurs were named each year. At least sauropodomorphs experienced a further increase in the number of named species in the 2010s, with an average of 9.3 new species having been named each year between 2009 and 2020. As a consequence, more sauropodomorphs were named between 1990 and 2020 than in all previous years combined. These new localities also led to improvements in overall specimen quality, with new species being increasingly named not on scrappy fossils but on more complete skeletons, sometimes from multiple individuals. Better specimens also led to new species being invalidated less frequently. Asian localities have produced

12177-438: The pair's rough methods: for example, their diggers often used dynamite to unearth bones. Modern paleontologists would find such methods crude and unacceptable, since blasting easily destroys fossil and stratigraphic evidence. Despite their unrefined methods, the contributions of Cope and Marsh to paleontology were vast: Marsh unearthed 86 new species of dinosaur and Cope discovered 56, a total of 142 new species. Cope's collection

12300-408: The presence of proteins such as collagen, elastin , and laminin . Both specimens yielded collagen protein sequences that were viable for molecular phylogenetic analyses , which grouped them with birds as would be expected. The extraction of fragmentary DNA has also been reported for both of these fossils, along with a specimen of Hypacrosaurus . In 2015, Sergio Bertazzo and colleagues reported

12423-458: The preservation of collagen fibres and red blood cells in eight Cretaceous dinosaur specimens that did not show any signs of exceptional preservation, indicating that soft tissue may be preserved more commonly than previously thought. Suggestions that these structures represent bacterial biofilms have been rejected, but cross-contamination remains a possibility that is difficult to detect. Dinosaurs diverged from their archosaur ancestors during

12546-503: The production of lime . The rich calcium carbonate shell has been used in the application for calcium deficiency therapies in humans and animals. A single eggshell has a mass of six grams which yields around 2200 mg of calcium (6000 mg × 0.95 × 0.4= 2280 mg). Eggshell particles are used in toothpaste as an anti-tartar agent. Powdered eggshells have been used for bone mineralization and growth. Recent applications of eggshells include producing calcium lactate as

12669-422: The rebbachisaurid Nigersaurus . 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 pachycephalosaurians. In the southern continents that had made up

12792-1404: The rocks that produced the Jehol (Early Cretaceous) and Yanliao (Mid-to-Late Jurassic) biotas of northeastern China, from which hundreds of dinosaur specimens bearing impressions of feather-like structures (both closely related to birds and otherwise, see § Origin of birds ) have been described by Xing Xu and colleagues. In living reptiles and mammals, pigment-storing cellular structures known as melanosomes are partially responsible for producing colouration. Both chemical traces of melanin and characteristically shaped melanosomes have been reported from feathers and scales of Jehol and Yanliao dinosaurs, including both theropods and ornithischians. This has enabled multiple full-body reconstructions of dinosaur colouration , such as for Sinosauropteryx and Psittacosaurus by Jakob Vinther and colleagues, and similar techniques have also been extended to dinosaur fossils from other localities. (However, some researchers have also suggested that fossilized melanosomes represent bacterial remains. ) Stomach contents in some Jehol and Yanliao dinosaurs closely related to birds have also provided indirect indications of diet and digestive system anatomy (e.g., crops ). More concrete evidence of internal anatomy has been reported in Scipionyx from

12915-450: The sauropodomorphs Bagualosaurus , Buriolestes , Guaibasaurus , Macrocollum , Nhandumirim , Pampadromaeus , Saturnalia , and Unaysaurus . The Pebbly Arkose Formation, which is of uncertain age but was likely comparable to the other two, has produced the sauropodomorph Mbiresaurus , along with an unnamed herrerasaurid. Less well-preserved remains of the sauropodomorphs Jaklapallisaurus and Nambalia , along with

13038-416: The sauropodomorphs Chromogisaurus , Eodromaeus , and Panphagia . Eoraptor 's likely resemblance to the common ancestor of all dinosaurs suggests that the first dinosaurs would have been small, bipedal predators . The Santa Maria Formation (radiometrically dated to be older, at 233.23 million years old ) has produced the herrerasaurids Gnathovorax and Staurikosaurus , along with

13161-571: The skeleton now mounted and on display at the Museum für Naturkunde in Berlin ; this mount is 12 meters (39 ft) tall and 21.8 to 22.5 meters (72 to 74 ft) long, and would have belonged to an animal that weighed between 30 000 and 60 000  kilograms ( 70 000 and 130 000  lb). The longest complete dinosaur is the 27 meters (89 ft) long Diplodocus , which was discovered in Wyoming in

13284-406: The skull behind the eyes), and as members of the diapsid group Archosauria, had additional openings in the snout and lower jaw. Additionally, several characteristics once thought to be synapomorphies are now known to have appeared before dinosaurs, or were absent in the earliest dinosaurs and independently evolved by different dinosaur groups. These include an elongated scapula , or shoulder blade;

13407-434: The sole surviving dinosaurs. In traditional taxonomy , birds were considered a separate class that had evolved from dinosaurs, a distinct superorder . However, most contemporary paleontologists reject the traditional style of classification based on anatomical similarity, in favor of phylogenetic taxonomy based on deduced ancestry, in which each group is defined as all descendants of a given founding genus. Birds belong to

13530-414: The species, turtles and tortoises lay hard or soft eggs. Several species lay eggs which are nearly indistinguishable from bird eggs. The bird egg is a fertilized gamete (or, in the case of some birds, such as chickens, possibly unfertilized) located on the yolk surface and surrounded by albumen , or egg white. The albumen in turn is surrounded by two shell membranes (inner and outer membranes) and then

13653-515: The specimen's excavation. Owen and Hooley subsequently described skin impressions of Hypsilophodon and Iguanodon in 1885 and 1917. Since then, scale impressions have been most frequently found among hadrosaurids, where the impressions are known from nearly the entire body across multiple specimens. Starting from the 1990s, major discoveries of exceptionally preserved fossils in deposits known as conservation Lagerstätten contributed to research on dinosaur soft tissues. Chiefly among these were

13776-527: The spread of ankylosaurians, iguanodontians , and brachiosaurids through Europe, North America, and northern Africa . These were later supplemented or replaced in Africa by large spinosaurid and carcharodontosaurid theropods, and rebbachisaurid and titanosaurian sauropods, also found in South America . In Asia , maniraptoran coelurosaurians like dromaeosaurids, troodontids , and oviraptorosaurians became

13899-468: The study of dinosaur systematics and evolution. Cladistic analysis, among other techniques, helps to compensate for an often incomplete and fragmentary fossil record. Reference books summarizing the state of dinosaur research, such as David B. Weishampel and colleagues' The Dinosauria , made knowledge more accessible and spurred further interest in dinosaur research. The release of the first and second editions of The Dinosauria in 1990 and 2004, and of

14022-405: The tallest of the theropods. The largest ornithischian dinosaur was probably the hadrosaurid Shantungosaurus giganteus which measured 16.6 meters (54 ft). The largest individuals may have weighed as much as 16 metric tons (18 short tons). Eggshell An eggshell is the outer covering of a hard-shelled egg and of some forms of eggs with soft outer coats. Nematode eggs present

14145-459: The taxonomic name has often been interpreted as a reference to dinosaurs' teeth, claws, and other fearsome characteristics, Owen intended it also to evoke their size and majesty. Owen recognized that the remains that had been found so far, Iguanodon , Megalosaurus and Hylaeosaurus , shared distinctive features, and so decided to present them as a distinct taxonomic group. As clarified by British geologist and historian Hugh Torrens, Owen had given

14268-399: The top of the formation. The sediments of the Dinosaur Park Formation are similar to those of the underlying Oldman Formation and they were originally included in that formation. The two formations are separated by a regional disconformity , however, and are distinguished by petrographic and sedimentologic differences. In addition, articulated skeletal remains and bonebeds are rare in

14391-849: The total number of dinosaur genera preserved in the fossil record at 1850, nearly 75% still undiscovered, and the number that ever existed (in or out of the fossil record) at 3,400. A 2016 estimate put the number of dinosaur species living in the Mesozoic at 1,543–2,468, compared to the number of modern-day birds (avian dinosaurs) at 10,806 species. Extinct dinosaurs, as well as modern birds, include genera that are herbivorous and others carnivorous, including seed-eaters, fish-eaters, insectivores, and omnivores. While dinosaurs were ancestrally bipedal (as are all modern birds), some evolved into quadrupeds, and others, such as Anchisaurus and Iguanodon , could walk as easily on two or four legs. Cranial modifications like horns and crests are common dinosaurian traits, and some extinct species had bony armor. Although

14514-410: The very top of the formation may indicate that a third distinct fauna had replaced the second during the transition into younger, non-Dinosaur Park sediments, at the same time an inland sea transgresses onto land, but there are fewer remains here. An unnamed pachyrhinosaur , Vagaceratops irvinensis , and Lambeosaurus magnicristatus may be more common in this third fauna. The timeline below follows

14637-522: The waste because the shells and the attached membrane attract vermin. When unseparated, the calcium carbonate eggshell and protein-rich membrane are useless. Recent inventions have allowed for the egg cracking industry to separate the eggshell from the eggshell membrane . The eggshell is mostly made up of calcium carbonate and the membrane is valuable protein. When separated both products have an array of uses. Monotremes , egg-laying mammals, lay soft-shelled eggs similar to those of reptiles. The shell

14760-402: Was a trait shared by many dinosaurs, both avian and non-avian. 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 . While

14883-452: Was an extremely important find: Hadrosaurus was one of the first nearly complete dinosaur skeletons found ( the first was in 1834, in Maidstone, England ), and it was clearly a bipedal creature. This was a revolutionary discovery as, until that point, most scientists had believed dinosaurs walked on four feet, like other lizards. Foulke's discoveries sparked a wave of interests in dinosaurs in

15006-485: Was an order of magnitude more massive than anything else that has since walked the Earth. Giant prehistoric mammals such as Paraceratherium (the largest land mammal ever) were dwarfed by the giant sauropods, and only modern whales approach or surpass them in size. There are several proposed advantages for the large size of sauropods, including protection from predation, reduction of energy use, and longevity, but it may be that

15129-450: Was purportedly discovered in 1822 by Mary Ann Mantell , the wife of English geologist Gideon Mantell , though this is disputed and some historians say Gideon had acquired remains years earlier. Gideon Mantell recognized similarities between his fossils and the bones of modern iguanas and published his findings in 1825. The study of these "great fossil lizards" soon became of great interest to European and American scientists, and in 1842

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