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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 Laurasia Origin[edit] Although Laurasia is known as a Mesozoic phenomenon, today it is believed that the same continents that formed the later Laurasia also existed as a coherent supercontinent after the breakup of Rodinia around 1 billion years ago. To avoid confusion with the Mesozoic continent, this is referred to as Proto-Laurasia. Breakup and reformation[edit] During the Cambrian, Laurasia was largely located in equatorial latitudes and began to break up, with North China and Siberia drifting into latitudes further north than those occupied by continents during the previous 500 million years. Siberia moved southwards and joined with Kazakhstania, a small continental region believed today to have been created during the Silurian by extensive volcanism. Final split[edit] Around 200 million years ago, Pangaea started to break up. See also[edit] References[edit]

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Archosaur Archosaurs are a group of diapsid amniotes whose living representatives consist of birds and crocodilians. This group also includes all extinct dinosaurs, extinct crocodilian relatives, and pterosaurs. Archosauria, the archosaur clade, is a crown group that includes the most recent common ancestor of living birds and crocodilians. It includes two main clades: Pseudosuchia, which includes crocodilians and their extinct relatives, and Avemetatarsalia, which includes birds and their extinct relatives (such as non-avian dinosaurs and pterosaurs). Distinguishing characteristics[edit] Archosaurs can be distinguished from other tetrapods on the basis of several synapomorphies, or shared characteristics, first found in a common ancestor. Origin of archosaurs[edit] There is some debate about when archosaurs first appeared. Archosaur takeover in the Triassic[edit] But archosaurs quickly became the dominant land vertebrates in the early Triassic. Main types of archosaurs[edit] Classification[edit]

Track and Field 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:

Gondwana The adjective Gondwanan is in common use in biogeography when referring to patterns of distribution of living organisms, typically when the organisms are restricted to two or more of the now-discontinuous regions that were once part of Gondwana, including the Antarctic flora. For example, the Proteaceae family of plants known only from southern South America, South Africa, Australia and New Zealand is considered to have a "Gondwanan distribution". This pattern is often considered to indicate an archaic, or relict, lineage. Formation[edit] The assembly of Gondwana was a protracted process. Gondwana was formed from the following earlier continents and microcontinents, among others, colliding in the following orogenies: Azania: much of central Madagascar, the Horn of Africa and parts of Yemen and Arabia. Reconstruction showing final stages of assembly of Gondwana, 550 Mya. One of the major sites of Gondwanan amalgamation was the East African Orogeny (Stern, 1994), where these[which?]

Dinosaures (TV Series 1991–1994 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.

Therapsida Therapsida is a group of synapsids, and includes mammals and their ancestors.[1][2] Many of the traits today seen as unique to mammals had their origin within early therapsids, including an erect posture. The earliest fossil attributed to Therapsida is Tetraceratops insignis from the Lower Permian.[3][4] Therapsids evolved from pelycosaurs (specifically sphenacodonts) 275 million years ago. They replaced the pelycosaurs as the dominant large land animals in the Middle Permian and were replaced, in turn, by the archosauromorphs in the Triassic, although one group of therapsids, the kannemeyeriiforms, remained diverse in the Late Triassic. The therapsids included the cynodonts, the group that gave rise to mammals in the Late Triassic around 225 million years ago. Of the non-mammalian therapsids, only cynodonts and dicynodonts survived the Triassic–Jurassic extinction event. Characteristics[edit] Legs and feet[edit] Jaw and teeth[edit] Evolutionary history[edit] Taxonomy[edit] Phylogeny[edit]

when i was 5 i loved dinos