Dinosaurs are many reptiles of the clover dinosaurs that first appeared during the Triassic period. Although the exact origin and timing of the development of dinosaurs is subject to active research, the original scientific consensus is between 231 and 243 million years. They were dominating field invertebrates after the Triassic Jurassic extinction event 201 million years ago. Its dominion continued through the Jurassic and Cretan periods and ended when the Cretaceous-Paleo-extinct event resulted in the extinction of most dinosaur groups 66 million years ago.
The fossil record indicates that birds are modern elastic dinosaurs developed by theropods during jury time. As such, the birds were the only dinosaurs that survived the mass destruction event. For the rest of this article, the term “dinosaur” is sometimes used to refer to the combined group of dinosaurs of birds (birds) and non-bird dinosaurs. On other occasions, it is used to refer specifically to non-bird dinosaurs, while bird dinosaurs are sometimes called “birds.” This article mainly refers to non-bird dinosaurs.
Dinosaurs are a diverse group of animals from taxonomic, morphological and ecological sites. Birds, in more than 10,000 live species, are the most diverse group of vertebrates except fish perceived. With fossil evidence, paleontologists have identified more than 500 different relatives and more than 1,000 different species of non-bird dinosaurs. Dinosaurs are present on all continents of the two existing species (birds) and fossil remains. During the first half of the 20th century before birds were considered dinosaurs, most scientists thought dinosaurs were slow and cold-blooded. However, most studies since the 1970s have shown that all dinosaurs were active animals with higher metabolism and many adjustments for social interaction. Some are herbivores, other carnivores. Evidence suggests that egg laying and bohus are additional features shared by all dinosaurs.
While the dinosaurs were ancestral bipeds, many extinct groups were quadruped and some could move from these positions. Exposure structures prepared as horns or ridges are developed for all dinosaur groups and some extinct skeleton-like groups such as bone armor and thorns. While dinosaurs, bird flu line current (birds) are usually small due to flight restrictions, many (not bird and bird) prehistoric dinosaurs were big bodies of larger dinosaurs sauropods are estimated to survive to have lengths Of 39, 7 feet (130 feet) and 18 feet (59 feet) heights, and they were the greatest land animals of all time. However, the idea that non-avian dinosaurs were large uniform prejudices based equivocally in part on conservation, take as large and resistant bones higher fossilization. Many dinosaurs were very small: Xixianykus, for example, was about 50 cm long.
Since the first dinosaur fossils were discovered in the early nineteenth century, fossilized dinosaur skeletons around the world in attractions museums were and dinosaurs were part of the world culture. The large size of some dinosaur groups and their seemingly monstrous and fantastic nature have ensured the regular appearance of dinosaurs in books and bestseller films such as Jurassic Park. The continued public enthusiasm for animals has led to major funding for dinosaur science and new discoveries are regularly covered by the media.
The taxon Dinosauria was formally named in 1842 by paleontologist Sir Richard Owen, who used to refer to the “distinct tribe or suborder of Saurian reptiles” that were later recognized in England and around the world. The term comes from the Greek words δεινός (deinos, “powerful” or “fear” big media “terrible”) and σαῦρος (sorrel, “lizard” or “reptile” means). Although the taxonomic name has often been interpreted as a reference to teeth, claws, and other fearsome dinosaur features, only to summon Owen’s anticipated size and majesty.
Prehistoric animals, including mosasaurs, ictiosaurios, plesiosaurios, pterosaurios and dimetrodon often often known as dinosaurs, are taxonomically classified not classified as dinosaurs.
Triceratops Skeleton, Los Angeles County Museum of Natural History
Phylogenetic nomenclature, dinosaurs are generally defined as the grouping of Triceratops, Neornithes, their last common ancestor (MRCA) and all descendants. It is also suggested that Dinosauria be defined with respect to the most recent common ancestor of Megalosaurus and Iguanodon, there were cites these two of the three classes of Richard Owen when he recognized the Dinosaur. Two definitions lead to the same set of animals, as defined dinosaurs “Dinosauria = Ornithischia + Saurischia” comprising ankylosauriani (quadrupeds herbivorous armored) stegosaurici (quadrupeds herbivorous paint), ceratopsiani (herbivorous quadrupeds with horns and fronds) ornitópodos (bipedal quadrupeds or herbivores including “duck-bills”), theropodi (mainly bipedal carnivores and birds) and sauropodomorfi (most large herbivorous quadrupeds long neck and tails).
Birds are now recognized as the only lifeline for Teropod dinosaur. In birds the traditional taxonomy was considered a separate class that evolved from the dinosaurs, an overlapping distinction. However, most contemporary paleontologists who are interested in dinosaurs reject the traditional style classification of phylogenetic taxonomy back; This approach requires that, for a group that is, of course, all descendants of group members should be added to the group. Therefore, birds are considered dinosaurs and why dinosaurs are not extinct. The birds are considered to subgroup Maniraptora that coelurosauri that are theropods, that are saurischianer, are classified the dinosaurs.
Suggested the search for Matthew Baron, David B. Norman and Paul M. Barrett in 2017, a radical review of dinosaurica systematically. Phylogenetic analysis of Baron et al. Ornithischia recovered as close to Theropoda compared to Sauropodomorpha, as opposed to the traditional association of theropods with Sauropodomorphen. The Ornithoscelida clade revives to refer to the group containing Ornithiachia and theropods. The same dinosaur was when the last common ancestor of Triceratops horridus, Passer domesticus, carnegii Diplodocus and defines all his descendants to ensure that sauropods and relatives remain trapped like dinosaurs.
Using one of the above definitions dinosaurs can generally be kept as an archosaur with hindlimb upright under the body. Many groups of prehistoric animals are popular as dinosaurs, such as ichthyosaurs, mosasaurs, plesiosaurs, pterosaurs and pelycosaurs (especially Dimetrodon), but not scientifically dinosaurized, and none had the upright hindlimb characteristic attitude of true dinosaurs. Dinosaurs were the dominant agricultural animals of the Mesozoic, especially the Jurassic and Cretaceous. Other groups of animals were limited in size and niches; Mammals, for example, rarely exceed the size of a domestic cat and rodent carnivores were usually the size of small dams.
Dinosaurs have always been a diverse group of animals; According to a 2006 study, more than 500 species of non-bird dinosaurs have so far been identified with certainty, and the total number of fossil-conserved genera is estimated to be around 1850, of which about 75% are identified. An earlier study predicts that over 3,400 dinosaur species existed, including many that have not been preserved in the fossils. For September 17, 2008, 1047 different species of dinosaurs were named.
In 2016, the estimated number of species of dinosaurs that existed in the Mesozoic was estimated to be 1,543-2,468. Some are herbivores, carnivores other, including grains eaters, fish eaters, insectivores and omnivores. While dinosaurs were ancestrally bipedal (like all modern birds), some prehistoric species were quadrupeds, and others, such as Ammosaurus and Iguanodon, might as well go on two or four legs. Cranial modifications such as horns and combs are common features of dinosaurs, and some species extinct had bony armor. Although it is known for the great size, many mesozoic dinosaurs were human size or smaller and modern birds are usually small. Dinosaurs populate every continent today and fossils show that the overall distribution had at least reached the early Jurassic. Modern birds live most of the available habitat from the land into the sea, and there are indications that some non-bird dinosaurs (like Microraptor) or at least sleds could fly, and others, like spinosaurids, had semiaquatic habits.
Although recent discoveries made it harder to present a list of commonly accepted features of the dinosaurs, sharing on almost every dinosaur discovered that there were certain modifications to the ancestral skeleton or clear ancestral dinosaurs These changes reflect ancient. Although some later groups of dinosaurs present more modified versions of the characteristics, they are considered to be typical of dinosaurs; They had the first dinosaurs and proceeded with their excerpt. Such modifications, originate from the common ancestors of a specific taxonomic group called the synapomorphies of such a group.
He confirmed a detailed assessment of the Archosurier relationship at Steirling Nesbitt and received the following six distinct synapomorphies:
In the skull its supratemporal Fossa (digging), the largest port is located in the front of the supratemporal Windows roof in the back of the skull
Epiphysis, obliquely back in the back upper corners, in the anterior cervical spine (above) behind the Atlas and Axis, the first two cervical vertebrae
The deltopectoral top of the ridge (accompanied by the protrusion of the deltopectorales muscles) or more than 30% of the humerus length (upper arm)
Ga, a lower arm bone shorter than 80% of the humerus
A fourth trochanter (projection containing the M. caudofemoral muscle is attached to the back axle) in the femur (sulphur) sharp flange
Trochanter Asymmetrical Fourth, with distal, lower edge, which is an angle more in relation to the back
On the talus and the calcaneus, the upper ankle bone, the joint adopts a proximal dimension that the upper connecting surface of the fibula is less than 30% of the transverse width of the element
The exoccipitals (bone in the back part of the skull) that are not found along the middle line in the bottom of the endocranial cavity, the internal space of the waist
In the pelvis, proximal articular surface of the ischium with ilio and the pubis at a concave surface (on the upper part of the ischium part of the open hook sections between the contact with the pubic bone and iliac separately)
Cynia cnemiale sauce (protruding part of the tibia color surface) anterolateral bends (forwardly and outwardly curves)
(Vertical), opposite the existing surface on the back surface of the distal end of the close tibia (the back surface of the lower end of the tibial bone)
(The upper surface of the calcaneus, where fibula is involved, log profile) Concave concave surface on the fibula the calcaneus
Nesbitt took some potential synapomorphies that could, and excluded some suggested synapomorphies. Some of them are in the Nesbitt recovery nervous Sistersaurus sister group, including an earlier anterior trochanter, II and IV metatarsals, a decreased duration of the contact between ischium and the presence of pubis on the tibia cnemial crest and the process of getting up on the talus and many more
A dinosaur shared several other skeletal characteristics. However, since they are common to other groups of alcoholic beverages or were not in all early dinosaurs, these elements are not synapomorphic into consideration. For example, how do diapsesid, two pairs of fenenestras (dialannacha in chroigeann behind the eyes) seriously and as members of the diaspora group Archosauria had additional openings in toy dinosaurs and a minor additive. On the other hand, it is known that the saintréitheanna thinks synapomorphies that now appeared before the dinosaurs, or were not present in the first dinosaurs with different groups of dinosaurs independently to succeed. These include the long shoulder blades or the shoulder blades; Sacrum of three or more fusion vertebrates (three are found in some other archosaurs, but only two in Herrerasaurus); And perforated acetabulum or acetabulum, with a hole in the center of its inner surface (closed in Saturnalia, for example). Heard the other difficulty of determining dineasáirigh often have a negative impact on the dinosaurs and other arcosaurios from the superior Triásico and were very similar; Sometimes these animals had a disability in the literature.
Géagaigh dinosaur make their bad build in a similar way to more modern mammals, but apart from most other reptiles, bringing their limbs on both sides. This attitude is because the development of death the program that faces the pelvis (usually an open socket) and that corresponds a particular house in the femur. Putting your posture erect dinosaurs soon enabled to breathe easily during movement, resistance and could levels of activity exceeded that allows reptiles to “ample” them. Perhaps the construction of the limb helped reduce the development of the great support by bending the limbs. Áirseanna were some fuses not built dineasáirigh, including rauisuchians, but these have been achieved through the configuration of “column building” the common iliac, in the projection, which is formed by the gromma in a bone socket of the hip is Swivel over the shelf to relieve.