Dinosaurs lived between 250 and 65 million years ago, from the early Triassic period to the end of the Cretaceous period. They were land-living reptiles, and (most) could not fly. Dinosaurs’ legs were straight, and projected downwards from the body. This set dinosaurs apart from early reptiles and crocodiles, whose legs projected outwards and were bent at the ‘knees’.
There were many different types of dinosaur, and they lived in many different habitats. There were meat-eating, plant-eating and omnivorous dinosaurs, and many evolved to have specialist diets such as seeds or insects. Dinosaurs can be classified into two groups: Saurischians and Ornitrisquios. have different characteristic features. Carnivores had sharp teeth and claws which stood them in good stead while going for hunting.
Dinosaurs lived in the Mesozoic Era, which is also known as the ‘Age of Reptiles’. It is subdivided into three smaller periods: the Triassic, Jurassic and Cretaceous periods. During the Triassic period, dinosaurs were small, and walked on two legs. Around 201.3 million years ago, a worldwide extinction event took place. It also set the scene for the dinosaurs to take over the world throughout the Jurassic and Cretaceous period. Dinosaurs became the dominant land vertebrates (animals with backbones) after the event.
Dinosaurs became extinct about 65 million years ago due to:
- Asteroid Impact: A massive asteroid hit the earth caused massive damage, including a giant dust cloud which lead to massive changes in the climate.
- Ice Age: Dinosaurs were thought to be cold blooded, it would have been hard for them to cope with such cold conditions.
- There was massive volcanic activity between 63 and 67 million years ago. This, would have caused a massive change in climate, which dinosaurs would have found hard to adapt to.
Scientists now think that all of today’s birds are descended from therapods, which were Saurischian dinosaurs.