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Age Determination Of Dinosaurs
Age determination in dinosaurs is mainly used to determine the approximate age of a dinosaur when the animal died. History Early attempts to estimate the longevity of dinosaurs used allometric scaling principles. Ages were determined by dividing individual mass estimates by rates of growth for similar, extant taxa. For very large individuals, growth rates were extrapolated to dinosaur proportions using regression analysis. The results of these investigations have been extremely variable as they depend on mass estimates and growth rates that are highly at odds with one another. For example, longevity estimates for the sauropod '' Hypselosaurus priscus'' range from a few decades to several hundred years. However, it has been shown that most dinosaur bones have growth lines that are visible in thin sectioned material viewed under a polarized light source. Growth lines Two types of growth lines exist: '' annuli'', and ''lines of arrested growth'' (LAGs).Francillion-Viellot H., ''et al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 the subject of active research. They became the dominant terrestrial vertebrates after the Triassic–Jurassic extinction event 201.3 mya; 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 the extinct non-avian dinosaurs, which are all dinosaurs other than birds. Dinosaurs are varied from taxonomic, morphological and ecological standpoints. Birds, at over 10,700 living species, are among ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ceratopsian
Ceratopsia or Ceratopia ( or ; Greek: "horned faces") is a group of herbivorous, beaked dinosaurs that thrived in what are now North America, Europe, and Asia, during the Cretaceous Period, although ancestral forms lived earlier, in the Jurassic. The earliest known ceratopsian, ''Yinlong downsi'', lived between 161.2 and 155.7 million years ago.Holtz, Thomas R. Jr. (2011) ''Dinosaurs: The Most Complete, Up-to-Date Encyclopedia for Dinosaur Lovers of All Ages,'Winter 2010 Appendix./ref> The last ceratopsian species, ''Triceratops prorsus'', became extinct during the Cretaceous–Paleogene extinction event, . ''Triceratops'' is by far the best-known ceratopsian to the general public. It is traditional for ceratopsian genus names to end in "''-ceratops''", although this is not always the case. One of the first named genera was ''Ceratops'' itself, which lent its name to the group, although it is considered a ''nomen dubium'' today as its fossil remains have no distinguishing characte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Troodon
''Troodon'' ( ; ''Troödon'' in older sources) is a wastebasket taxon and a dubious genus of relatively small, bird-like dinosaurs known definitively from the Campanian age of the Late Cretaceous period (about 77 mya). It includes at least one species, ''Troodon formosus'', known from Montana. Discovered in October 1855, ''T. formosus'' was among the first dinosaurs found in North America, although it was thought to be a lizard until 1877. Several well-known troodontid specimens from the Dinosaur Park Formation in Alberta were once believed to be members of this genus. However, recent analyses in 2017 have found the genus to be undiagnostic and referred some of these specimens to the genus ''Stenonychosaurus'' (long believed to be synonymous with ''Troodon'') and others to the genus ''Latenivenatrix''. The genus name is Ancient Greek for "wounding tooth", referring to the teeth, which were different from those of most other theropods known at the time of their discovery. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maniraptor
Maniraptora is a clade of coelurosaurian dinosaurs which includes the birds and the non-avian dinosaurs that were more closely related to them than to ''Ornithomimus velox''. It contains the major subgroups Avialae, Deinonychosauria, Oviraptorosauria and Therizinosauria. ''Ornitholestes'' and the Alvarezsauroidea are also often included. Together with the next closest sister group, the Ornithomimosauria, Maniraptora comprises the more inclusive clade Maniraptoriformes. Maniraptorans first appear in the fossil record during the Jurassic Period (see ''Eshanosaurus''), and survive today as living birds. Description Maniraptorans are characterized by long arms and three-fingered hands (though reduced or fused in some lineages), as well as a "half-moon shaped" (semi-lunate) bone in the wrist (carpus). In 2004, Tom Holtz and Halszka Osmólska pointed out six other maniraptoran characters relating to specific details of the skeleton. Unlike most other saurischian dinosaurs, which have ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megapnosaurus
''Megapnosaurus'' (meaning "big dead lizard", from Greek μεγα = "big", 'απνοος = "not breathing", "dead", σαυρος = "lizard") is an extinct genus of coelophysid theropod dinosaur that lived approximately 188 million years ago during the early part of the Jurassic Period in what is now Africa. The species was a small to medium-sized, lightly built, ground-dwelling, bipedal carnivore, that could grow up to long and weigh up to . It was originally given the genus name ''Syntarsus'', but that name was later determined to be preoccupied by a beetle. The species was subsequently given a new genus name, ''Megapnosaurus,'' by Ivie, Ślipiński & Węgrzynowicz in 2001. Some studies have classified it as a species within the genus ''Coelophysis,'' but this interpretation has been challenged by more subsequent studies and the genus is now considered valid. Discovery and history The first fossils of ''Megapnosaurus'' were found in 1963 by a group of students from Northlea S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coelophysoid
Coelophysoidea were common dinosaurs of the Late Triassic and Early Jurassic periods. They were widespread geographically, probably living on all continents. Coelophysoids were all slender, carnivorous forms with a superficial similarity to the coelurosaurs, with which they were formerly classified, and some species had delicate cranial crests. Sizes range from about 1 to 6 m in length. It is unknown what kind of external covering coelophysoids had, and various artists have portrayed them as either scaly or feathered. Some species may have lived in packs, as inferred from sites where numerous individuals have been found together. Examples of coelophysoids include ''Coelophysis'', ''Procompsognathus'' and '' Liliensternus''. Most dinosaurs formerly referred to as being in the dubious taxon "Podokesauridae" are now classified as coelophysoids. Classification Despite their very early occurrence in the fossil record, coelophysoids have a number of derived features that separate th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Narindasaurus
''Narindasaurus'' (meaning "lizard of Narinda Bay") is a genus of turiasaurian sauropod dinosaur from the Middle Jurassic Isalo III Formation of Madagascar. The type species, ''N. thevenini'' was formally described by Royo-Torres ''et al.'' in 2020. The holotype, which consists of one specimen, is currently stored at the Muséum national d’Histoire naturelle and has been since 1906 or 1907. Discovery and naming The holotype was discovered in the Isalo III Formation before 1894 by Joseph Thomas Last, and were briefly noted on by Paul Lemoine in 1906.Lemoine P. 1906. Études géologiques dans le nord de Madagascar. In: Herman A, ed. Contributions à l’histoire géologique de l’Océan Indien. ''Paris: Librairie Scientifique'', 1–520. Armand Thevenin (1861-1942) was the first to diagnose ''Narindasaurus''. In 1907, he placed it within the now obsolete species "'' Bothriospondylus madagascariensis''", which is now known as ''Lapparentosaurus ''Lapparentosaurus'' is a g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lapparentosaurus
''Lapparentosaurus'' is a genus of sauropod dinosaur from the Middle Jurassic. Its fossils were found in Madagascar (Isalo III Formation). The type species is ''L. madagascariensis''. Discovery and naming In 1895 Richard Lydekker named a new species of ''Bothriospondylus'', ''B. madagascariensis'' based on fossils found before 1894 by Joseph Thomas Last in the Majunga Basin in layers of the Bathonian, the Isalo III Formation. Because there was no real connection with this English form, in 1986 José Fernando Bonaparte named a separate genus. The type species, the only known, is ''Lapparentosaurus madagascariensis''. The generic name honours Albert-Félix de Lapparent. The holotype assigned by Bonaparte, MAA 91-92, consists of two neural arches. Much more abundant material has been referred, from at least three but perhaps as much as ten individuals from different growth stages. This includes vertebrae and limb elements but no skulls. The species is still lacking a good descri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Massospondylus
''Massospondylus'' ( ; from Greek, (massōn, "longer") and (spondylos, "vertebra")) is a genus of sauropodomorph dinosaur from the Early Jurassic. (Hettangian to Pliensbachian ages, ca. 200–183 million years ago). It was described by Sir Richard Owen in 1854 from remains discovered in South Africa, and is thus one of the first dinosaurs to have been named. Fossils have since been found at other locations in South Africa, Lesotho, and Zimbabwe. Material from Arizona's Kayenta Formation, India, and Argentina has been assigned to the genus at various times, but the Arizonan and Argentinian material are now assigned to other genera. The type species is ''M. carinatus''; seven other species have been named during the past 150 years, but only ''M. kaalae'' is still considered valid. Early sauropodomorph systematics have undergone numerous revisions during the last several years, and many scientists disagree where exactly ''Massospondylus'' lies on the dinosaur evolutiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prosauropod
Sauropodomorpha ( ; from Greek, meaning "lizard-footed forms") is an extinct clade of long-necked, herbivorous, saurischian dinosaurs that includes the sauropods and their ancestral relatives. Sauropods generally grew to very large sizes, had long necks and tails, were quadrupedal, and became the largest animals to ever walk the Earth. The ''prosauropods,'' which preceded the sauropods, were smaller and were often able to walk on two legs. The sauropodomorphs were the dominant terrestrial herbivores throughout much of the Mesozoic Era, from their origins in the Late Triassic (approximately 230 Ma) until their decline and extinction at the end of the Cretaceous. Description Sauropodomorphs were adapted to browsing higher than any other contemporary herbivore, giving them access to high tree foliage. This feeding strategy is supported by many of their defining characteristics, such as: a light, tiny skull on the end of a long neck (with ten or more elongated cervical vertebrae) a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psittacosaurus
''Psittacosaurus'' ( ; "parrot lizard") is a genus of extinct ceratopsian dinosaur from the Early Cretaceous of what is now Asia, existing between 126 and 101 million years ago. It is notable for being the most species-rich non-avian dinosaur genus. Up to 12 species are known, from across China, Mongolia, Russia, and Thailand. The species of ''Psittacosaurus'' were obligate bipeds at adulthood, with a high skull and a robust beak. One individual was found preserved with long filaments on the tail, similar to those of ''Tianyulong''. ''Psittacosaurus'' probably had complex behaviours, based on the proportions and relative size of the brain. It may have been active for short periods of time during the day and night, and had well-developed senses of smell and vision. ''Psittacosaurus'' was one of the earliest ceratopsians, but closer to ''Triceratops'' than ''Yinlong''. Once in its own family, Psittacosauridae, with other genera like ''Hongshanosaurus'', it is now considered to be s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paleontologists
Paleontology (), also spelled palaeontology or palæontology, is the scientific study of life that existed prior to, and sometimes including, the start of the Holocene epoch (roughly 11,700 years before present). It includes the study of fossils to classify organisms and study their interactions with each other and their environments (their paleoecology). Paleontological observations have been documented as far back as the 5th century BC. The science became established in the 18th century as a result of Georges Cuvier's work on comparative anatomy, and developed rapidly in the 19th century. The term itself originates from Greek (, "old, ancient"), (, ( gen. ), "being, creature"), and (, "speech, thought, study"). Paleontology lies on the border between biology and geology, but differs from archaeology in that it excludes the study of anatomically modern humans. It now uses techniques drawn from a wide range of sciences, including biochemistry, mathematics, and engineering ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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