Description
Dinosaurs (the first name is the correct translation of Dinosauria, the scientific name of the group) form an animal group belonging to the Archosauria, which dates back to the Mesozoic era. The Dinosauria originated approximately 230 million years ago in the Triassic, as a split within the broader group of the Dinosauriformes. The first dinosaur was a small bipedal carnivore. It was the direct ancestor of the two main groups into which all other dinosaurs can be subdivided: the Saurischia and the Ornithischia. Herbivorous species soon developed within both of these groups as well. Dinosaurs became dominant towards the end of the Triassic, when most other large animals on land became extinct. During the subsequent Jurassic and Cretaceous periods, dinosaurs were the dominant land animals for 140 million years, presumably the largest that ever lived. Thousands of species, both carnivores and herbivores, developed in all kinds of forms, partly due to the movement of the continents. However, the marine reptiles of that time and the pterosaurs, flying reptiles, were not dinosaurs. At the end of the Cretaceous period, 66 million years ago, most dinosaurs became extinct, possibly as a result of a meteorite impact. The dinosaurs still alive today are birds. Since 1808, the extinct dinosaurs have been scientifically described, and the group received its name in 1842, which means “formidable saurians.” Between 1870 and 1925, many dinosaur fossils were discovered, especially in North America. After that, interest declined significantly, but since 1968 there has been a considerable resurgence of research, the so-called “Dinosaur Renaissance.” Hundreds of new species have been found, particularly in Argentina. Greatly improved insights have been gained regarding their relationships, anatomy, and way of life. As a result, earlier popular science books on the subject have become completely outdated. Due to the diversity of dinosaur forms, it is difficult to identify typical characteristics of the group. It is not a specific characteristic that makes an animal a dinosaur, but the fact that it descends from the first dinosaur. Besides large dinosaurs, there were and are also very small ones. Dinosaurs are reptiles and have at least partially scaly skin and reproduce by means of eggs. Unlike other modern reptiles, existing dinosaurs—the birds—are warm-blooded. It is unknown and disputed to what extent extinct dinosaurs were warm-blooded and possessed feathers or fur. Small species of dinosaurs, even if they were not birds, presumably had a high metabolism, and several of their fossils show the remains of feathers or hair. Most scientists now believe that all dinosaurs, even the largest ones, were fairly active animals rather than sluggish or clumsy, which explains their evolutionary success.
