Padian, Kevin, ed. (1986). The Origin of Birds and the Evolution of Flight. Memoirs of the California Academy of Sciences. Vol.8. San Francisco, CA: California Academy of Sciences. ISBN 978-0-940228-14-6. OCLC 946083441. OL 9826926M.

By human standards, dinosaurs were creatures of fantastic appearance and often enormous size. As such, they have captured the popular imagination and become an enduring part of human culture. The entry of the word "dinosaur" into the common vernacular reflects the animals' cultural importance: in English, "dinosaur" is commonly used to describe anything that is impractically large, obsolete, or bound for extinction. [329]

Dinosaur crafts and activities

Paul, Gregory S., ed. (2000). The Scientific American Book of Dinosaurs (1sted.). New York: St. Martin's Press. ISBN 978-0-312-26226-6. LCCN 2001269051. OCLC 45256074. a b Bakker, R.T. (1972). "Anatomical and Ecological Evidence of Endothermy in Dinosaurs". Nature. 238 (5359): 81–85. Bibcode: 1972Natur.238...81B. doi: 10.1038/238081a0. S2CID 4176132. Langer, Max C.; Abdala, Fernando; Richter, Martha; Benton, Michael J. (1999). "Un dinosaure sauropodomorphe dans le Trias supérieur (Carnien) du Sud du Brésil" [A sauropodomorph dinosaur from the Upper Triassic (Carman) of southern Brazil]. Comptes Rendus de l'Académie des Sciences, Série IIA. Amsterdam: Elsevier on behalf of the French Academy of Sciences. 329 (7): 511–517. Bibcode: 1999CRASE.329..511L. doi: 10.1016/S1251-8050(00)80025-7. ISSN 1251-8050. 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 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. [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] 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)

Organ, C.L.; Schweitzer, M.H.; Zheng, W.; Freimark, L.M.; Cantley, L.C.; Asara, J.M. (2008). "Molecular Phylogenetics of Mastodon and Tyrannosaurus rex". Science. 320 (5875): 499. Bibcode: 2008Sci...320..499O. doi: 10.1126/science.1154284. PMID 18436782. S2CID 24971064. a b Brett-Surman, M. K.; Holtz, Thomas R.; Farlow, James O. (June 27, 2012). The Complete Dinosaur. Indiana University Press. p.25. ISBN 978-0-253-00849-7. The smallest dinosaur known is the bee hummingbird, [156] with a length of only 5 centimeters (2.0in) and mass of around 1.8g (0.063oz). [157] The smallest known non- avialan dinosaurs were about the size of pigeons and were those theropods most closely related to birds. [158] For example, Anchiornis huxleyi is currently the smallest non-avialan dinosaur described from an adult specimen, with an estimated weight of 110g (3.9oz) [159] and a total skeletal length of 34 centimeters (1.12ft). [158] [159] The smallest herbivorous non-avialan dinosaurs included Microceratus and Wannanosaurus, at about 60 centimeters (2.0ft) long each. [160] [161] Behavior A nesting ground of the hadrosaur Maiasaura peeblesorum was discovered in 1978 Cnemial crest on the tibia (protruding part of the top surface of the shinbone) arcs anterolaterally (curves to the front and the outer side)a b c d Weishampel, Dodson & Osmólska 2004, pp.7–19, chpt. 1: "Origin and Relationships of Dinosauria" by Michael J. Benton. Cashmore, D.D.; Butler, R.J. (2019). "Skeletal completeness of the non-avian theropod dinosaur fossil record". Palaeontology. 62 (6): 951–981. doi: 10.1111/pala.12436. S2CID 197571209.

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 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. [15] [16] General description Triceratops skeleton, Natural History Museum of Los Angeles County

Ceratosauria (generally elaborately horned carnivores that existed from the Jurassic to Cretaceous periods, originally included Coelophysoidea) 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 Holmes, Thom (1998). Fossil Feud: The Rivalry of the First American Dinosaur Hunters. Parsippany, NJ: Julian Messner. ISBN 978-0-382-39149-1. LCCN 96013610. OCLC 34472600. a b c St. Fleur, Nicholas (December 8, 2016). "That Thing With Feathers Trapped in Amber? It Was a Dinosaur Tail". Trilobites. The New York Times. New York. ISSN 0362-4331. Archived from the original on August 31, 2017 . Retrieved December 8, 2016.

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, the number of named genera began to increase exponentially in the 1990s. [21] As of 2008, [update] over 30 new 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 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. [67] 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. [66] Asian localities have produced the most complete theropod specimens, [68] while North American localities have produced the most complete sauropodomorph specimens. [67]Scientists will probably never be certain of the largest and smallest dinosaurs to have ever existed. This is because only a tiny percentage of animals were ever fossilized and most of these remain buried in the earth. Few of the specimens that are recovered are complete skeletons, and impressions of skin and other 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 human Scholarly descriptions of what would now be recognized as dinosaur bones first appeared in the late 17th century in England. Part of a bone, now known to have been the femur of a Megalosaurus, [43] 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). [44] He correctly identified 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. [45] [46] Edward Lhuyd, a friend of Sir Isaac Newton, published Lithophylacii Britannici ichnographia (1699), the first scientific treatment of what would now be recognized as a dinosaur when he described and named a sauropod tooth, " Rutellum impicatum", [47] [48] that had been found in Caswell, near Witney, Oxfordshire. [49] Sir Richard Owen's coining of the word dinosaur, in the 1842 revised version of his talk at an 1841 meeting of the British Association for the Advancement of Science. Zhou, Z.-H.; Wang, Y. (2017). "Vertebrate assemblages of the Jurassic Yanliao Biota and the Early Cretaceous Jehol Biota: Comparisons and implications". Palaeoworld. 26 (2): 241–252. doi: 10.1016/j.palwor.2017.01.002. Lessem, Don; Glut, Donald F. (1993). The Dinosaur Society's Dinosaur Encyclopedia. Illustrations by Tracy Lee Ford; scientific advisors, Peter Dodson, et al. New York: Random House. ISBN 978-0-679-41770-5. LCCN 94117716. OCLC 30361459 . Retrieved October 30, 2019. Tyrannosaurus, a late Cretaceous dinosaur. This large and powerful predator had an enormous head and jaws equipped with serrated teeth for eating flesh. (more)