The Dinosauria (from the ancient Greek ιεινός / deinόs "terrible" and σαῦρος / saûros "lizard" 1, a), more commonly called dinosaurs, form a super-order as well as an extremely diverse clade of sauropsids of the diapsid subclass. . They are oviparous archosaurs, having in common an erect posture and sharing a number of synapomorphies such as the presence of an elongated deltopectoral ridge at the level of the humerus and an acetabulum perforating the pelvis. Present from the middle of Ladinian (last stage of the Middle Triassic), about 240 Ma ago, the non-avian branch of dinosaurs completely disappeared during the Cretaceous-Paleogene extinction 66 Ma ago. Birds, the avian branch of the dinosaurs, emerged from small theropod dinosaurs of the Late Jurassic. Thus the survival of birds to this extinction, their considerable diversification during the Cenozoic, makes them the only living group of dinosaurs today.
This group of predominantly terrestrial vertebrates experienced considerable evolutionary success in the Mesozoic, dominating the continental faunas between the Upper Triassic and the Upper Cretaceous for more than 170 Ma. Present on all continents from the end of the Triassic, they include very various terrestrial and flying animals, bipeds and quadrupeds, carnivores and herbivores, having developed a whole series of skeletal and integumentary innovations such as horns, ridges, plates and feathers. Non-avian dinosaurs are among them the largest and heaviest animals to exist on land. Nevertheless, a large number of dinosaurs did not exceed the size of a human being, and some of them were smaller than a hen.
The standard classification of dinosaurs distinguishes two large clades according to the morphology of their pelvis: Ornithischia and Saurischia. The Ornithischia (or Ornithischians) only include herbivorous dinosaurs that paleontologists divide into three major groups: the Ornithopoda which includes mainly bipedal dinosaurs including the famous "duck-billed" dinosaurs (or Hadrosauridae), the Marginocephalia which include dinosaurs frill and bony dome on the top of the head (Ceratopsia and Pachycephalosauria respectively), and finally Thyreophora which include quadrupedal dinosaurs surmounted by armor, spikes and bony plates on the back and tail (the Ankylosauria and the Stegosauria). The Saurischia (or Saurischians) are divided into two distinct clades, the Theropoda which includes bipedal dinosaurs and all carnivorous and piscivorous dinosaurs as well as feathered dinosaurs and flying dinosaurs (mostly birds), and the Sauropodomorpha, generally four-legged and very large animals with a long neck, a small head and a long tail.
In 2017, a revision of this classification was proposed by Matthew Baron and his colleagues, by grouping on the one hand theropods and ornithischians within the same clade (ornithoscelidsb) and on the other hand sauropodomorphs and herasaurids in within the saurischian clade (which therefore no longer includes theropods) 2,3,4.
The term Dinosauria was proposed by the English paleontologist Richard Owen in April 1842. From the mid-nineteenth century until the end of the 1960s, dinosaurs were considered by scientists to be giant lizards, cold-blooded, clumsy reptiles. and slow, having disappeared at the end of the Mesozoic victims of their stupidity. Begun by the American paleontologist John Ostrom in 1969, the "renaissance of the dinosaurs" is characterized by a renewed interest in the study of dinosaurs, which were therefore recognized as active animals, probably endothermic even if not all studies. disagree, and having complex social behaviors, quite distinct from our current reptiles.
Since their discovery, dinosaurs aroused great public interest and the reconstructions of skeletons unveiled during exhibitions have always been major attractions in museums around the world. Dinosaurs have become an integral part of po[CENSORED]r culture in the twentieth and twenty-first centuries, appearing in a plethora of successful books and films such as Jurassic Park and Ice Age 3. Today, if a "dinomania Affects certain children in particular, po[CENSORED]r curiosity has never wavered and new discoveries regularly reported by the media maintain a certain fascination for these animals. The word "dinosaur" has passed into common parlance and its often inconsiderate use tends to falsely attribute this term to other extinct animals such as pterosaurs, marine reptiles (mosasaurs, plesiosaurs, etc.) and mammalian reptiles such as Dimetrodon or Edaphosaurus which