06.13.23 ┆ Truth about the dollar disaster for savers 🧾️

There's a darker truth behind this political event... [Logotype]( Nеw Cаsh Lаw Will Be Disaster for Savers [Dоllars]( Nеw law has expert warning seniors and retirees to beware. There's a darker truth behind this political event... [Read The Full Story Нere.]( Logotype Moneу And Markets Watchdog is dedicated to providing readers like you with unique opportunities. The message below from one of our business associates is one we believe you should take a serіous look at. [Logotype]( This email was sent by D/B/A M&MWatchdog. © 2023 M&MWatchdog. Аll Rights Reserved. 525 Junction Road, Madison, WI 53717 Follow This Steps To [whitelist us.]( Thinking about unsubscribing? Just tap the link is below. [Privacy Policy]( | [Update Profile]( | [Tеrms & Conditions]( | [Unsubscrіbe]( espite their unrefined methods, the contributions of Cope and Marsh to paleontology were vast: Marsh unearthed 86 nw species of dinosaur and Cope discovered 56, a total of 142 nw species. Cope's collection is nw at the American Museum of Natural History in Nw York City, while Marsh's is at the Peabody Museum of Natural History at Yale University.[59] "Dinosaur renaissance" and beyond Main article: Dinosaur renaissance John Ostrom's original restoration of Deinonychus, published in 1969 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.[60][61] At the end of the 1960s, however, the field of dinosaur research experienced a surge in activity that remains ongoing.[62] 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.[60] Concurrently, Robert T. Bakker published a series of studies that likewise argued for active lifestyles in dinosaurs based on anatomical and ecological evidence (see § Physiology),[63][64] which were subsequently summarized in his 1986 book The Dinosaur Heresies.[65] Paleontologist Robert T. Bakker with a mounted skeleton of a tyrannosaurid (Gorgosaurus libratus) Ne revelations were supported by an increase in dinosaur discoveries. Major nw 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, the number of named genera began to increase exponentially in the 1990s.[21] As of 2008, over 30 nw species of dinosaurs were named each year.[66] At least sauropodomorphs experienced a further increase in the number of named species in the 2010s, with an average of 9.3 ew species having been named each year between 2009 and 2020. As a consequence, more sauropodomorphs were named between 1990 and 2020 than in ll previous years combined.[67] These ne localities also led to improvements in overall specimen quality, with nw species being increasingly named not on scrappy fossils but on more complete skeletons, sometimes from multiple individuals. Better specimens also led to nw species being invalidated less frequently.[66] Asian localities have produced the most complete theropod specimens,[68] while North American localities have produced the most complete sauropodomorph specimens.[67] 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 the study of dinosaur systematics and evolution. Cladistic analysis, among other techniques, helps to compensate for an often incomplete and fragmentary fossil record.[69][70] Reference books summarizing the state of dinosaur research, such as David B. Weishampel and colleagues' The Dinosauria, made knowledge more accessible[71] and spurred further interest in dinosaur research. The release of the first and second editions of The Dinosauria in 1990 and 2004, and of a review paper by Paul Sereno in 1998, were accompanied by increases in the number of published phylogenetic trees for dinosaurs.[72] Soft tissue and molecular preservation An Edmontosaurus specimen's skin impressions found in 1999 Dinosaur fossils are not limied 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.[73] 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 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 suject to further study by Reginald Hooley in 1917.[74] Among ornithischians, in 1884 Jacob Wortman found skin impressions on the first known specimen of Edmontosaurus annectens, which were largely destroyed during the specimen's excavation.[75] Owen and Hooley subsequently described skin impressions of Hypsilophodon and Iguanodon in 1885 and 1917.[74] Since then, scale impressions have been most frequently found among hadrosaurids, where the impressions are known from nearly the entire body across multiple specimens.[76] Colour restoration of Sinosauropteryx Colour restoration of Psittacosaurus Starting from the 1990s, major discoveries of exceptionally preserved fossils in deposits known as conservation Lagerstätten contributed to research on dinosaur soft tissues.[77][78] Chiefly among these were 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.[79][80] In living reptiles and mammals, pigment-storing cellular structures known as melanosomes are partially responsible for producing colouration.[81][82] 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.[83] This has enabled multiple full-body reconstructions of dinosaur colouration, such as for Sinosauropteryx[84] and Psittacosaurus[85] by Jakob Vinther and colleagues, and similar techniques have also been extended to dinosaur fossils from other localities.[81] (However, some researchers have also suggested that fossilized melanosomes represent bacterial remains.[86][87]) Stomach contents in some Jehol and Yanliao dinosaurs closely related to birds have also provided indirect indications of dit and digestive system anatomy (e.g., crops).[88][89] More concrete evidence of internal anatomy has been reported in Scipionyx from the Pietraroja Plattenkalk of Italy. It preserves portions of the intestines, colon, liver, muscles, and windpipe.[90] Scipionyx fossil with intestines, Natural History Museum of Milan 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.[91][92][93] However, in 2005, Schweitzer and colleagues reported that 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.[94] This discovery suggested that original soft tissues could be preserved over geological time,[73] with multiple mechanisms having been proposed.[95] Later, in 2009, Schweitzer and colleagues reported that a Brachylophosaurus femur preserved similar microstructures, and immunohistochemical techniques (based on antibody binding) demonstrated the presence of proteins such as collagen, elastin, and laminin.[96] Both specimens yielded collagen protein sequences that were viable for molecular phylogenetic analyses, which grouped them with birds as would be expected.[96][97] The extraction of fragmentary DNA has also been reported for both of these fossils,[98] along with a specimen of Hypacrosaurus.[99] In 2015, Sergio Bertazzo and colleagues reported 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.[100] Suggestions that these structures represent bacterial biofilms[101] have been rejected,[102] but cross-contamination remains a possibility that is difficult to detect.[103] Evolutionary history Origins and early evolution Full skeleton of an early carnivorous dinosaur, displayed in a glass case in a museum The early dinosaurs Herrerasaurus (large), Eoraptor (small) and a Plateosaurus skull, from the Triassic Dinosaurs diverged from their archosaur ancestors during the Middle to Late Triassic epochs, roughly 20 millin years after the devastating Permian–Triassic extinction event wiped out an estimated 9 of al marine species and 70 of terrestrial vertebrate species approximately 252 millin years ago.[104][105] The oldest dinosaur fossils known from substantial remains date to the Carnian epoch of the Triassic period and have been found primarily in the Ischigualasto and Santa Maria Formations of Argentina, and the Pebbly Arkose Formation of Zimbabwe.[106] The Ischigualasto Formation (radiometrically dated at 231-230 millon years old[107]) has produced the early saurischian Eoraptor, originally considered a meber of the Herrerasauridae[108] but ow considered to be an early sauropodomorph, along with the herrerasaurids Herrerasaurus and Sanjuansaurus, and the sauropodomorphs Chromogisaurus, Eodromaeus, and Panphagia.[109] Eoraptor's likely resemblance to the common ancestor of al dinosaurs suggests that the first dinosaurs would have been small, bipedal predators.[110][111][112] The Santa Maria Formation (radiometrically dated to be older, at 233.23 illion years old[113]) has produced the herrerasaurids Gnathovorax and Staurikosaurus, along with the sauropodomorphs Bagualosaurus, Buriolestes, Guaibasaurus, Macrocollum, Nhandumirim, Pampadromaeus, Saturnalia, and Unaysaurus.[109] 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.[106] Less well-preserved remains of the sauropodomorphs Jaklapallisaurus and Nambalia, along with the early saurischian Alwalkeria, are known from the Upper Maleri and Lower Maleri Formations of India.[114] 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.[109][115] Dinosaurs may have appeared as early as the Anisian epoch of the Triassic, approximately 245 millin 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 ony a close relative.[116] The referral of the Manda Formation to the Anisian is also uncertain. Regardless, dinosaurs existed alongside non-dinosaurian ornithodirans for a period of time, with estimates ranging from 5–10 millon years[117] to 21 illion years.[113] 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 the dinosaurs.[118] Most of these other animals became extinct in the Triassic, in one of two events. First, at about 215 milion years ago, a variety of basal archosauromorphs, including the protorosaurs, became extinct. This was followed by the Triassic–Jurassic extinction event (about 201 millon 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,[119][120] and the exact date of their extinction is uncertain. These losses left behind a land fauna of crocodylomorphs, dinosaurs, mammals, pterosaurians, and turtles.[10] 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.[12] Also notably, there was a heightened rat of extinction during the Carnian pluvial event.[121] Evolution and paleobiogeography The supercontinent Pangaea in the early Mesozoic (around 200 millin years ago) 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.[122] Gymnosperm plants (particularly conifers), 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.[123] 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 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.[122] 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 the mouth, including potential cheek-like organs to keep food in the mouth, and jaw motions to grind food.[123] Another notable evolutionary event of the Jurassic was the appearance of true birds, descended from maniraptoran coelurosaurians.[14] 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 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 the common theropods, and ankylosaurids and early ceratopsians like Psittacosaurus became important herbivores. Meanwhile, Australia was hme to a fauna of basal ankylosaurians, hypsilophodonts, and iguanodontians.[122] 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 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.[123] Some sauropods also evolved tooth batteries, best exemplified by the rebbachisaurid Nigersaurus.[124] 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 the nw-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.[122] Flowering plants were greatly radiating,[123] with the first grasses appearing by the end of the Cretaceous.[125] 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.[123] The Cretaceous–Paleogene extinction event, which occurred approximately 66 illion years ago at the end of the Cretaceous, caused the extinction of ll 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.[126] 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 enantiornithines, aquatic hesperornithines, and even the larger terrestrial theropods (in the for of Gastornis, eogruiids, bathornithids, ratites, geranoidids, mihirungs, and "terror birds"). It 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.[127] Terror birds and bathornithids occupied carnivorous guilds alongside predatory mammals,[128][129] and ratites are still fairly successful as mid-sized herbivores; eogruiids similarly lasted from the Eocene to Pliocene, becoming extinct onl very recently after over 20 milion years of co-existence with many mammal groups.[130] Classification Main article: Dinosaur classification Saurischian pelvis structure (left side) Tyrannosaurus pelvis (showing saurischian structure – left side) Ornithischian pelvis structure (left side) Edmontosaurus pelvis (showing ornithischian structure – left side) 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.[30] 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 al 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 the hip structure of their ancestors, with a pubis bone directed cranially, or forward.[37] This basic fom was modified by rotating the pubis backward to varying degrees in several groups (Herrerasaurus,[131] therizinosauroids,[132] dromaeosaurids,[133] and birds[14]). Saurischia includes the theropods (exclusively bipedal and with a wide variety of diets) and sauropodomorphs (long-necked herbivores which include advanced, quadrupedal groups).[29][134] 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 additional forward-pointing process. Ornithischia includes a variety of species that were primarily herbivores. Despite the tems "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".[30] Taxonomy 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.[135] Further details and other hypotheses of classification may be found on individual articles. Dinosauria Restoration of six ornithopods; far left: Camptosaurus, left: Iguanodon, center background: Shantungosaurus, center foreground: Dryosaurus, right: Corythosaurus, far right (large) Tenontosaurus. †Ornithischia ("bird-hipped"; diverse bipedal and quadrupedal herbivores) †Heterodontosauridae (small herbivores/omnivores with prominent canine-like teeth) †Genasauria ("cheeked lizards") †Thyreophora (armored dinosaurs; bipeds and quadrupeds) †Eurypoda (heavy, quadrupedal thyreophorans) †Stegosauria (spikes and plates as primary armor) †Huayangosauridae (small stegosaurs with flank osteoderms and tail clubs) †Stegosauridae (large stegosaurs) †Ankylosauria (scutes as primary armor) †Parankylosauria (small, southern ankylosaurs with macuahuitl-like tails) †Nodosauridae (mostly spiky, club-less ankylosaurs) †Ankylosauridae (characterized by flat scutes) †Ankylosaurinae (club-tailed ankylosaurids) †Neornithischia ("nw ornithischians") †Cerapoda ("horned feet") †Marginocephalia (characterized by a cranial growth) Restoration of four ceratopsids: top left - Triceratops, top right - Styracosaurus, bottom left - Anchiceratops, bottom right - Chasmosaurus. †Pachycephalosauria (bipeds with domed or knobby growth on skulls) †Ceratopsia (bipeds and quadrupeds; many had neck frills and horns) †Chaoyangsauridae (small, frill-less basal ceratopsians) †Neoceratopsia ("nw ceratopsians") †Leptoceratopsidae (little to no frills, hornless, with robust jaws) †Protoceratopsidae (basal ceratopsians with small frills and stubby horns) †Ceratopsoidea (large-horned ceratopsians) †Ceratopsidae (large, elaborately ornamented ceratopsians) †Chasmosaurinae (ceratopsids with enlarged brow horns) †Triceratopsini (very large chasmosaurines with long brow horns) †Centrosaurinae (ceratopsids mostly characterized by frill and nasal ornamentation) †Nasutoceratopsini (centrosaurines with enlarged nasal cavities) †Centrosaurini (centrosaurines with enlarged nasal horns) †Pachyrhinosaurini (mostly had nasal bosses instead of horns) †Ornithopoda (various sizes; bipeds and quadrupeds; evolved a method of chewing using skull flexibility and numerous teeth) †Jeholosauridae (small Asian neornithischians) †Thescelosauridae ("wondrous lizards") †Orodrominae (burrowers) †Thescelosaurinae (large thescelosaurids) †Iguanodontia ("iguana teeth"; advanced ornithopods) †Elasmaria (mostly southern ornithopods with mineralized plates along the ribs; may be thescelosaurids) †Rhabdodontomorpha (with distinctive dentition) †Rhabdodontidae (European rhabdodontomorphs) †Dryosauridae (mid-sized, small headed) †Camptosauridae (mid-sized, stocky) †Styracosterna ("spiked sterna") †Hadrosauriformes (ancestrally had a thumb spike) †Hadrosauroidea (large quadrupedal herbivores, with teeth merged into dental batteries) †Hadrosauromorpha (hadrosaurids and their closest relatives) †Hadrosauridae ("duck-billed dinosaurs"; often with crests) †Saurolophinae (hadrosaurids with solid, small, no crests) †Brachylophosaurini (short-crested) †Kritosaurini (enlarged, solid nasal crests) †Saurolophini (small, spike-like crests) †Edmontosaurini (flat-headed saurolophines) †Lambeosaurinae (hadrosaurids often with hollow crests) †Aralosaurini (solid-crested) †Tsintaosaurini (vertical, tube-like crests) †Parasaurolophini (long, backwards-arcing crests) †Lambeosaurini (usually rounded crests) Saurischia †Herrerasauridae (early bipedal carnivores) Restoration of four macronarian sauropods: from left to right Camarasaurus, Brachiosaurus, Giraffatitan, and Euhelopus †Sauropodomorpha (herbivores with small heads, long necks, and long tails) †Unaysauridae (primitive, strictly bipedal "prosauropods") †Plateosauria (diverse; bipeds and quadrupeds) †Massospondylidae (long-necked, primitive sauropodomorphs) †Riojasauridae (large, primitive sauropodomorphs) †Sauropodiformes (heavy, bipeds and quadrupeds) †Sauropoda (very large and heavy; quadrupedal) †Lessemsauridae (gigantic yet lacking several weight-saving adaptations) †Gravisauria ("heavy lizards") †Eusauropoda ("true sauropods") †Turiasauria (often large, widespread sauropods) †Neosauropoda ("nw sauropods"; columnar limbs) †Diplodocoidea (skulls and tails elongated; teeth typically narrow and pencil-like) †Rebbachisauridae (short-necked, low-browsing diplodocoids often with high backs) †Flagellicaudata (whip-tailed) †Dicraeosauridae (small, short-necked diplodocoids with enlarged cervical and dorsal vertebrae) †Diplodocidae (extremely long-necked) †Apatosaurinae (robust cervical vertebrae) †Diplodocinae (long, thin necks) †Macronaria (boxy skulls; spoon- or pencil-shaped teeth) †Titanosauriformes ("titan lizard forms") †Brachiosauridae (long-necked, long-armed macronarians) †Somphospondyli ("porous vertebrae") †Euhelopodidae (stocky, mostly Asian) †Titanosauria (diverse; stocky, with wide hips; most common in the Late Cretaceous of southern continents) Theropoda (carnivorous) Neotheropoda ("ew theropods") †Coelophysoidea (early theropods; includes Coelophysis and close relatives) †"Dilophosaur-grade neotheropods" (larger kink-snouted dinosaurs) Averostra ("bird snouts") †Ceratosauria (generally elaborately horned carnivores that existed from the Jurassic to Cretaceous periods, originally included Coelophysoidea) †Ceratosauridae (ceratosaurs with large teeth) †Abelisauroidea (ceratosaurs exemplified by reduced arms and hands) †Abelisauridae (large abelisauroids with short arms and oftentimes elaborate facial ornamentation) †Noasauridae (diverse, generally light theropods; may include several obscure taxa) †Elaphrosaurinae (bird-like; omnivorous as juveniles but herbivorous as adults) †Noasaurinae (small carnivores) Tetanurae (stiff-tailed dinosaurs) †Megalosauroidea (early group of large carnivores) †Piatnitzkysauridae (small basal megalosauroids endemic to the Americas) †Megalosauridae (large megalosauroids with powerful arms and hands) †Spinosauridae (crocodile-like, semiaquatic carnivores) Avetheropoda ("bird theropods") †Megaraptora (theropods with large hand claws; either carnosaurs or coelurosaurs, potentially tyrannosauroids) †Carnosauria (large meat-eating dinosaurs; megalosauroids sometimes included) †Metriacanthosauridae (primitive Asian allosauroids) †Allosauridae (Allosaurus and its very closest relatives) †Carcharodontosauria (robust allosauroids) †Carcharodontosauridae (includes some of the largest purely terrestrial carnivores) †Neovenatoridae ("nw hunters"; may include megaraptorans) Coelurosauria (feathered theropods, with a range of body sizes and niches) †"Nexus of basal coelurosaurs" (used by Tweet to denote well-known taxa with unstable positions at the base of Coelurosauria) Tyrannoraptora ("tyrant thieves") †Compsognathidae (small early coelurosaurs with short forelimbs) †Tyrannosauroidea (mostly large, primitive coelurosaurs) †Proceratosauridae (tyrannosauroids with head crests) †Tyrannosauridae (Tyrannosaurus and close relatives) Maniraptoriformes (bird-like dinosaurs) †Ornithomimosauria (small-headed, mostly toothless, omnivorous or possible herbivores) †Ornithomimidae (very ostrich-like dinosaurs) Maniraptora (dinosaurs with pennaceous feathers) Restoration of six dromaeosaurid theropods: from left to right Microraptor, Velociraptor, Austroraptor, Dromaeosaurus, Utahraptor, and Deinonychus †Alvarezsauroidea (small hunters with reduced forelimbs) †Alvarezsauridae (insectivores with oly one enlarged digit) †Therizinosauria (tall, long-necked theropods; omnivores and herbivores) †Therizinosauroidea (larger therizinosaurs) †Therizinosauridae (sloth-like herbivores, often with enlarged claws) †Oviraptorosauria (omnivorous, beaked dinosaurs) †Caudipteridae (bird-like, basal oviraptorosaurs) †Caenagnathoidea (cassowary-like oviraptorosaurs) †Caenagnathidae (toothless oviraptorosaurs known from North America and Asia) †Oviraptoridae (characterized by two bony projections at the back of the mouth; exclusive to Asia) Paraves (avialans and their closest relatives) †Scansoriopterygidae (small tree-climbing theropods with membranous wings) †Deinonychosauria (toe-clawed dinosaurs; may not frm a natural group) †Archaeopterygidae (small, winged theropods or primitive birds) †Troodontidae (omnivores; enlarged brain cavities) †Dromaeosauridae ("raptors") †Microraptoria (characterized by large wings on both the arms and legs; may have been capable of powered flight) †Eudromaeosauria (hunters with greatly enlarged sickle claws) †Unenlagiidae (piscivores; may be dromaeosaurids) †Halszkaraptorinae (duck-like; potentially semiaquatic) †Unenlagiinae (long-snouted) Avialae (modern birds and extinct relatives) Timeline of major groups Timeline of major dinosaur groups per Holtz (2007). Paleobiology 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.[90][94] 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).[136][137] Two topics of particular interest and study have been dinosaur size and behavior.[138] Size Main article: Dinosaur size Scale diagram comparing the average hman to the longest known dinosaurs in five major clades: Sauropoda (Supersaurus vivianae) Ornithopoda (Shantungosaurus giganteus) Theropoda (Spinosaurus aegyptiacus) Thyreophora (Stegosaurus ungulatus) Marginocephalia (Triceratops prorsus) Current evidence suggests that dinosaur average size varied through the Triassic, Early Jurassic, Late Jurassic and Cretaceous.[111] Predatory theropod dinosaurs, which occupied most terrestrial carnivore niches during the Mesozoic, most often fall into the 100 to 1000 kg (220 to 2200 lb) category when sorted by estimated weight into categories based on ordr of magnitude, whereas recent predatory carnivoran mammals peak in the 10 to 100 kg (22 to 220 lb) category.[139] The mode of Mesozoic dinosaur body masses is between 1 and 10 metric tons (1.1 and 11.0 short tons).[140] 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).[141] 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 orer 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 nly modern whales approach or surpass them in size.[142] 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 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.[143] Largest and smallest Scientists will probably ever be certain of the largest and smallest dinosaurs to have ever existed. This is because ony 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 soft tissues are rare. Rebuilding a complete skeleton by comparing the size and morphology of bones to those of similar, better-known species is an inexact art, and reconstructing the muscles and other organs of the living animal is, at best, a process of educated guesswork.[144] Comparative size of Argentinosaurus to the average hman 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 nw mounted and on display at the Museum für Naturkunde in Berlin;[145] this mount is 12 meters (39 ft) tall and 21.8 to 22.5 meters (72 to 74 ft) long,[146][147] and would have belonged to an animal that weighed between 30000 and 60000 kilograms (70000 and 130000 lb). The longest complete dinosaur is the 27 meters (89 ft) long Diplodocus, which was discovered in Wyoming in the United States and displayed in Pittsburgh's Carnegie Museum of Natural History in 1907.[148] The longest dinosaur known from good fossil material is Patagotitan: the skeleton mount in the American Museum of Natural History in Nw York is 37 meters (121 ft) long. The Museo Municipal Carmen Funes in Plaza Huincul, Argentina, has an Argentinosaurus reconstructed skeleton mount that is 39.7 meters (130 ft) long.[149]