Answer:
Dinosaurs
Dinosaurs were the main animals on Earth for more than 150 million years. They were lizardlike reptiles. Some of them were the largest and scariest creatures that ever walked on land. The word dinosaur comes from Greek words meaning “terrible lizard.”
The last dinosaurs became extinct, or died out, about 65.5 million years ago. Fossils of dinosaurs were first discovered in the early 1800s. Fossils are remains or impressions of a plant or animal that have been preserved in rock. By studying these fossils, scientists know that dinosaurs were the ancient cousins of today’s crocodiles, snakes, and lizards. Scientists also believe that today’s birds descended from dinosaurs.
Dinosaurs did not have any hair. Their skin had a bumpy or pebbly surface. Some scientists believe that dinosaurs were gray or green in color. These colors would have helped the dinosaurs blend in with their surroundings. Other scientists think that dinosaurs were very colorful. Bright colors would have helped males get the attention of females.
Scientists have divided dinosaurs into two large groups. The groups are based on the way a dinosaur’s hip bones were shaped. One group is the Ornithischia, or bird-hipped dinosaurs. Members of this group are called ornithischians. The other is the Saurischia, or lizard-hipped dinosaurs. Members of this group are called saurischians.
Dinosaurs roamed the Earth over 200 million years ago and were the dominant terrestrial vertebrate for 135 million years. It is believed their extinction came about because of changes in the climate they couldn’t adapt to. Birds are the closest relative to a dinosaur that we have. Below are some interesting facts about dinosaurs.
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Dinosaurs walked the earth for over 165 million years.
- They lived during a period of time known as the Mesozoic Era, or Age of Reptiles.
- At the end of the Cretaceous Period they became extinct – that was around 65 million years ago. During this time there was a great deal of volcanic activity and many earthquakes.
- Many people believe that dinosaurs became extinct because an asteroid hit the earth changing the climate dramatically. It is believed that dinosaurs couldn’t adapt to these changes.
- The word dinosaur means terrifying lizard. This name was invented by Sir Richard Owen in 1842.
- The oldest known dinosaur is Eoraptor, a meat-eater that lived 228 million years ago.
- Most dinosaurs hatch from eggs, and they could not fly or live in water.
- Dinosaurs are classified as reptiles. They are divided into two groups based on the structure of the hip. One group has lizard-like hips and the other group has bird-like hips.
- The biggest dinosaurs were over 100 feet long and 50 feet tall… the sauropod was the largest dinosaur… the smallest dinosaurs were the size of a chicken and were called mussaurus, or mouse lizard.
- Some dinosaurs were carnivores, meat-eaters, and some were herbivores, plant eaters. Some walked on two legs, while others walked on all four legs. Some had horns and spikes, others had thick bumpy skin, and some even had feathers.
- The color of all dinosaurs is unknown because no one was alive at that time in history.
- There are currently over 330 described dinosaur species and this number is growing.
Summary:
Dinosaurs are land-based animals which lived from 230 million to 60 million years ago. Scientists study dinosaurs by looking at bone and egg fossils, footprint track ways, and by using our knowledge of dinosaurs' living relatives. Some dinosaurs were as small as modern birds, while others weighed many tons. Scientists have been able to put together entire dinosaur skeletons, but they still don't know what color their skin was or whether or not they had feathers.
