Читать книгу Dinosaurs - Douglas Palmer - Страница 7

Since the early decades of the 19th century, fossil hunters have dug up hundreds of different kinds of ancient reptiles that we now know as dinosaurs. From tiny bird-sized creatures to the largest animals ever to have lived on land, the dinosaurs were an extraordinary group of animals. Ancient peoples populated their myths and legends with all sorts of strange monsters such as dragons. Today, the role of these creatures has been filled by the dinosaurs – real animals, many of which were just as strange as any fictional beast.

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Therizinosaurus, fantastic fiction or actual dinosaur?

The dinosaurs first appeared around 230 million years ago and altogether form a special group of reptiles with certain distinct characters that were first recognized in the mid-19th century by the English anatomist Richard Owen. These features are preserved in the structure of their skeletons, especially their hip bones, and they separate dinosaurs from other reptiles both living and extinct. A number of extinct and distant reptile relatives of the dinosaurs, such as the flying pterosaurs and the sea-dwelling ichthyosaurs and plesiosaurs, are often described as if they were dinosaurs, but this is not the case.

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Iguanodon, first described by Gideon Mantell.

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Ornithomimus, a small and agile Ostrich-like dinosaur.

Caption: A crocodile, a living relative of the dinosaurs.

The closest living relatives to the dinosaurs are the birds and crocodiles, with which they share certain features. All three groups share the presence of extra openings in the skull and jaw. With the birds they have in common lightly built bones, the bony structure of their legs, a hinged ankle, and aspects of the skull and jaws. And while the dinosaurs are also similar to crocodiles, they differ from them and other reptiles in the bone structure of their legs, feet and hips. Crocodiles, like most other living reptiles, sprawl with their limbs held out to the side of the body. However, the dinosaurs have their limbs tucked in under the body, a structure that allows them to walk and run more efficiently.

The image and idea of dinosaurs as once living animals has changed enormously since their fossil remains were first discovered and recognized as belonging to a distinct group of extinct reptiles. Even the iconic status of the giant meat eaters like Tyrannosaurus rex has been partly displaced by that of small, fast-moving and highly active predators, some of which are known to have been covered with hairlike down and feathers.

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Archaeopteryx, a feathered dinosaur descendant.