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Dinosaur

Dinosaurs are a diverse group of animals of the clade Dinosauria. They first appeared during the Triassic period, 231.4 million years ago, and were the dominant terrestrial vertebrates for 135 million years, from the beginning of the Jurassic (about 201 million years ago) until the end of the Cretaceous (66 million years ago), when the Cretaceous–Paleogene extinction event led to the extinction of most dinosaur groups at the close of the Mesozoic Era. The fossil record indicates that birds evolved from theropod dinosaurs during the Jurassic Period and, consequently, they are considered a subgroup of dinosaurs by many paleontologists.[1] Some birds survived the extinction event that occurred 66 million years ago, and their descendants continue the dinosaur lineage to the present day.[2] Etymology Definition The common House Sparrow (Passer domesticus) is often used to represent modern birds in definitions of the group Dinosauria General description Distinguishing anatomical features Related:  Tree of Life - Phylogenetic systematics

Tree of Life.pdf Carcharodontosauridae Evolution[edit] Giganotosaurus skeleton cast, Haifa Along with the spinosaurids, carcharodontosaurids were the largest predators in the early and middle Cretaceous throughout Gondwana, with species also present in North America (Acrocanthosaurus), and Asia (Shaochilong).[5] Their ages range from the Barremian (127-121 million years ago) to the Turonian (93-89 million years ago). Past the Turonian, they might have been replaced by the smaller abelisaurids in Gondwana and by tyrannosaurids in North America and Asia. Classification[edit] The family Carcharodontosauridae was originally named by Ernst Stromer in 1931 to include the single newly discovered species Carcharodontosaurus saharicus. With the discovery of Mapusaurus in 2006, Rodolfo Coria and Phil Currie erected a subfamily of Carcharodontosauridae, the Giganotosaurinae, to contain the most advanced South American species, which they found to be more closely related to each other than to the African and European forms.

Bird Modern birds are characterised by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. Extant birds have wings; the most recent species without wings was the moa, which is generally considered to have become extinct in the 16th century. Wings are evolved forelimbs, and most bird species can fly. Many species are economically important, mostly as game or poultry. Evolution and classification Definition Aves and a sister group, the clade Crocodilia, contain the only living representatives of the reptile clade Archosauria. Gauthier[8] identified four conflicting ways of defining the term "Aves", which is a problem because the same biological name is being used four different ways. Under the fourth definition Archaeopteryx is an avialan, and not a member of Aves. Most researchers define Avialae as branch-based clade, though definitions vary. Dinosaurs and the origin of birds Early diversity

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Sauropoda The name Sauropoda was coined by O.C. Marsh in 1878, and is derived from Greek, meaning "lizard foot".[2] Sauropods are one of the most recognizable groups of dinosaurs, and have become a fixture in popular culture due to their large sizes. Complete sauropod fossil finds are rare. Many species, especially the largest, are known only from isolated and disarticulated bones. Many near-complete specimens lack heads, tail tips and limbs. Description[edit] Sauropods were herbivorous (plant-eating), usually quite long-necked[3] quadrupeds (four-legged), often with spatulate (spatula-shaped: broad at the base, narrow at the neck) teeth. Size[edit] Size comparison of selected giant sauropod dinosaurs The sauropods' most defining characteristic was their size. Their body structure did not vary as much as other dinosaurs, perhaps due to size constraints, but they displayed ample variety. Others, like the brachiosaurids, were extremely tall, with high shoulders and extremely long necks. Air sacs[edit]

Cretaceous The Cretaceous (/krɨˈteɪʃəs/, krə-TAY-shəs), derived from the Latin "creta" (chalk), usually abbreviated K for its German translation Kreide (chalk), is a geologic period and system from circa 145 ± 4 to 66 million years (Ma) ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the Cenozoic era. It is the last period of the Mesozoic Era, and, spanning 79 million years, the longest period of the Phanerozoic Eon. Geology[edit] Key events in the Cretaceous An approximate timescale of key Cretaceous events. Research history[edit] Stratigraphic subdivisions[edit] As with other older geologic periods, the rock beds of the Cretaceous are well identified but the exact ages of the system's base is uncertain by a few million years. Rock formations[edit] The high eustatic sea level and warm climate of the Cretaceous meant a large area of the continents was covered by warm shallow seas. Paleogeography[edit] Climate[edit] Life[edit]

International Code of Zoological Nomenclature How names are correctly established in the frame of binominal nomenclatureWhich name must be used in case of name conflictsHow scientific literature must cite names Zoological nomenclature is independent of other systems of nomenclature, for example botanical nomenclature. This implies that animals can have the same generic names as plants. In other words, whether a species itself is or is not a recognized entity is a subjective decision, but what name should be applied to it is not. The Code is also retroactive or retrospective, which means that previous editions of the Code, or previous other rules and conventions have no force any more today,[1] and the nomenclatural acts published 'back in the old times' must be evaluated only under the present edition of the Code. Principles[edit] In regulating the names of animals it holds by six central principles, which were first set out (as Principles) in the third edition of the Code (1985): Principle of binominal nomenclature[edit] Example:

Ceratosauria Ceratosaurs are members of a group of theropod dinosaurs defined as all theropods sharing a more recent common ancestry with Ceratosaurus than with birds. There is no agreed upon listing of species or diagnostic characters of Ceratosauria, though they were less derived anatomically than the more diverse Tetanurae. According to the latest and most accepted theory, Ceratosauria includes the Late Jurassic to Late Cretaceous theropods Ceratosaurus, Elaphrosaurus, and Abelisaurus, found primarily (though not exclusively) in the Southern Hemisphere. Relationships[edit] The following cladogram follows an analysis by Diego Pol and Oliver W. Distribution through time[edit] References[edit] External links[edit] Ceratosauria at DinoData

Jurassic Etymology[edit] The chronostratigraphic term "Jurassic" is directly linked to the Jura Mountains. Alexander von Humboldt recognized the mainly limestone dominated mountain range of the Jura Mountains as a separate formation that had not been included in the established stratigraphic system defined by Abraham Gottlob Werner, and he named it "Jurakalk" in 1795.[4][5][6][7] The name "Jura" is derived from the Celtic root "jor", which was Latinised into "juria", meaning forest (i.e., "Jura" is forest mountains).[5][6][8] Divisions[edit] Key events in the Jurassic An approximate timescale of key Jurassic events. Various dinosaurs roamed forests of similarly large conifers during the Jurassic period. Paleogeography and tectonics[edit] During the early Jurassic period, the supercontinent Pangaea broke up into the northern supercontinent Laurasia and the southern supercontinent Gondwana; the Gulf of Mexico opened in the new rift between North America and what is now Mexico's Yucatan Peninsula.

Taxon The idea of a "natural system" of classification goes back to the dawn of scientific nomenclature in the mid-18th century, as indicated by the title of Carolus Linnaeus' 1758 Systema Naturae. Systematists since that time have striven to determine the true classification of the diversity of life, which was at that time thought to reflect the Plan of Creation. Today it is common to define a "good taxon" as one that reflects evolutionary (phylogenetic) relationships. This is not mandatory, as is evident from commonly used words for non-monophyletic entities such as invertebrates, conifers and fish. A taxon may be given a formal scientific name, the application of which is governed by one of the Nomenclature Codes, which set out rules to determine which scientific name is correct for that particular grouping. Many modern systematists using cladistic methods, including advocates of phylogenetic nomenclature, require taxa to be monophyletic, consisting of all descendants of some ancestor.

Abelisauridae Like most theropods, abelisaurids were carnivorous bipeds. They were characterized by stocky hindlimbs and extensive ornamentation of the skull bones, with grooves and pits. In many abelisaurids, like Carnotaurus, the forelimbs are vestigial, the skull is shorter and bony crests grows above the eyes. Description[edit] Reconstructed Abelisaurus skull, "Dinosaurs of Patagonia" exhibit. Carnotaurus skeleton, Natural History Museum, London Skull[edit] Although skull proportions varied, abelisaurid skulls were generally very tall and very short in length. Forelimbs and hands[edit] More primitive relatives such as Noasaurus and Ceratosaurus had longer, mobile arms with fingers and claws.[8] Hind limbs[edit] Abelisaurid hindlimbs were more typical of ceratosaurs, with the astragalus and calcaneum (upper ankle bones) fused to each other and to the tibia, forming a tibiotarsus. Distribution[edit] Classification[edit] Shared characteristics[edit] Size comparison between abelisaurid genera and human.

Triassic The Triassic began in the wake of the Permian–Triassic extinction event, which left the Earth's biosphere impoverished; it would take well into the middle of the period for life to recover its former diversity. Therapsids and archosaurs were the chief terrestrial vertebrates during this time. A specialized subgroup of archosaurs, dinosaurs, first appeared in the Late Triassic but did not become dominant until the succeeding Jurassic.[5] The first true mammals, themselves a specialized subgroup of Therapsids also evolved during this period, as well as the first flying vertebrates, the pterosaurs, who like the dinosaurs were a specialized subgroup of archosaurs. The vast supercontinent of Pangaea existed until the mid-Triassic, after which it began to gradually rift into two separate landmasses, Laurasia to the north and Gondwana to the south. The global climate during the Triassic was mostly hot and dry,[6] with deserts spanning much of Pangaea's interior. Dating and subdivisions[edit]

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