小葛装饰
The DinosauriaDinosaurs, one of the most successful groups of animals (in terms of longevity) that have ever lived, evolved into many diverse sizes and shapes, with many equally diverse modes of living. The term "Dinosauria" was invented by Sir Richard Owen in 1842 to describe these "fearfully great reptiles," specifically Megalosaurus, Iguanodon, and Hylaeosaurus, the only three dinosaurs known at the time. The creatures that we normally think of as dinosaurs lived during the Mesozoic Era, from late in the Triassic period (about 225 million years ago) until the end of the Cretaceous (about 65 million years ago). But we now know that they actually live on today as the birds. Running Deinonychus. © 1995 B. CunninghamSome things to keep in mind about dinosaurs:• Not everything big and dead is a dinosaur. All too often, books written (or movies made) for a popular audience include animals such as mammoths, mastodons, pterosaurs, plesiosaurs, ichthyosaurs, and the sail-backed Dimetrodon. Dinosaurs are a specific subgroup of the archosaurs, a group that also includes crocodiles, pterosaurs, and birds. although pterosaurs are close relations, they are not true dinosaurs. Even more distantly related to dinosaurs are the marine reptiles, which include the plesiosaurs and ichthyosaurs. Mammoths and mastodons are mammals and did not appear until many millions of years after the close of the Cretaceous period. Dimetrodon is neither a reptile nor a mammal, but a basal synapsid, i.e., an early relative of the ancestors of mammals.• Not all dinosaurs lived at the same time. Different dinosaurs lived at different times. Despite the portrayals in movies like King Kong and Jurassic Park, no Stegosaurus ever saw a Tyrannosaurus, because Tyrannosaurus didn't appear on the scene until 80 or so million years following the extinction of stegosaurs. The same goes for Apatosaurus ("Brontosaurus") — it's bones were already well-fossilized by the time T. rex came along.• Dinosaurs are not extinct. Technically. Based on features of the skeleton, most people studying dinosaurs consider birds to be dinosaurs. This shocking realization makes even the smallest hummingbird a legitimate dinosaur. So rather than refer to "dinosaurs" and birds as discrete, separate groups, it is best to refer to the traditional, extinct animals as "non-avian dinosaurs" and birds as, well, birds, or "avian dinosaurs." It is incorrect to say that dinosaurs are extinct, because they have left living descendants in the form of cockatoos, cassowaries, and their pals — just like modern vertebrates are still vertebrates even though their Cambrian ancestors are long extinct.
shuixinggege
What is a Dinosaur?Millions of years ago, long before there were any people, there were dinosaurs. Dinosaurs were one of several kinds of prehistoric reptiles that lived during the Mesozoic Era, the "Age of Reptiles." Dinosaurs were reptiles and most hatched from eggs. No dinosaurs could fly and none lived in the water. Plant-eating sauropods were the largest animals to ever walk on Earth - but blue whales are more massive than any of the dinosaurs were! The largest dinosaurs were over 100 feet (30 m) long and up to 50 feet (15 m) tall (like Argentinosaurus, Seismosaurus, Ultrasauros, Brachiosaurus, and Supersaurus). The smallest dinosaurs, like Compsognathus, were about the size of a chicken. Most dinosaurs were in-between. It is very difficult to figure out how the dinosaurs sounded, how they behaved, how they mated, what color they were, or even how to tell whether a fossil was male or female. were vertebrate animals that dominated terrestrial ecosystems for over 160 million years, first appearing approximately 230 million years ago. At the end of the Cretaceous Period, 65 million years ago, dinosaurs succumbed to a catastrophic extinction, which ended their dominance on land. Taxonomists consider modern birds to be the direct descendants of theropod dinosaurs.Since the first dinosaur was recognized in the 19th century, mounted, fossilized dinosaur skeletons have become major attractions at museums around the world. Dinosaurs have become a part of world culture and remain consistently popular among children and adults alike. They have been featured in best-selling books and films such as Jurassic Park, and new discoveries are regularly covered by the media.The term dinosaur is sometimes used informally to describe other prehistoric reptiles, such as the pelycosaur Dimetrodon, the winged pterosaurs and the aquatic ichthyosaurs, plesiosaurs and mosasaurs, although technically none of these were dinosaurs.
鹿脸脸舅舅
Dinosaurs were reptiles that lived through three periods of Earth's geologic history: Triassic (208-245 million years ago), Jurassic (145-208 million years ago), and Cretaceous (65-145 million years ago). Different species of dinosaurs flourished and then became extinct throughout these three periods.All dinosaurs were reptiles, but not all reptiles were dinosaurs. Even though the name "dinosaur" means "terrible lizard," dinosaurs were not lizards at all.Some Key Dinosaur FactsAll dinosaurs had four limbs. Some walked on all four legs; others, on their two back legs.Dinosaur legs were positioned below their bodies, making it possible for them to walk upright. Lizard legs are positioned outward from their bodies, giving them a sprawling posture.Dinosaur legs were positioned under their bodies. They were able to walk and run very efficiently.Dinosaurs lived on land. They did not fly in the air or live in water.Some dinosaurs were carnivores (meat-eaters), but most were herbivores (plant-eaters).Not all dinosaurs were large. The smallest, Compsognathus, was about 3 feet long (1 m). One of the largest, Barosaurus, reached 80 feet (24 m). Tyrannosaurus rex measured 46 feet (14 m).
薰妍maggiel
What is a Dinosaur? Millions of years ago, long before there were any people, there were dinosaurs. Dinosaurs were one of several kinds of prehistoric reptiles that lived during the Mesozoic Era, the "Age of Reptiles." Dinosaurs were reptiles and most hatched from eggs. No dinosaurs could fly and none lived in the water. Plant-eating sauropods were the largest animals to ever walk on Earth - but blue whales are more massive than any of the dinosaurs were! The largest dinosaurs were over 100 feet (30 m) long and up to 50 feet (15 m) tall (like Argentinosaurus, Seismosaurus, Ultrasauros, Brachiosaurus, and Supersaurus). The smallest dinosaurs, like Compsognathus, were about the size of a chicken. Most dinosaurs were in-between. It is very difficult to figure out how the dinosaurs sounded, how they behaved, how they mated, what color they were, or even how to tell whether a fossil was male or female. Dinosaurs were vertebrate animals that dominated terrestrial ecosystems for over 160 million years, first appearing approximately 230 million years ago. At the end of the Cretaceous Period, 65 million years ago, dinosaurs succumbed to a catastrophic extinction, which ended their dominance on land. Taxonomists consider modern birds to be the direct descendants of theropod dinosaurs. Since the first dinosaur was recognized in the 19th century, mounted, fossilized dinosaur skeletons have become major attractions at museums around the world. Dinosaurs have become a part of world culture and remain consistently popular among children and adults alike. They have been featured in best-selling books and films such as Jurassic Park, and new discoveries are regularly covered by the media. The term dinosaur is sometimes used informally to describe other prehistoric reptiles, such as the pelycosaur Dimetrodon, the winged pterosaurs and the aquatic ichthyosaurs, plesiosaurs and mosasaurs, although technically none of these were dinosaurs.
