Animals become extinct for a variety of reasons. In the past, several animal species became extinct through natural causes such as climate change. However, the extinction rate today is higher because of deforestation, habitat loss, overhunting, pollution and other human activities. Here are some examples: Dinosaurs became extinct about 65 million years ago. Scientists have different theories about their extinction such as climate change, meteor showers and volcanoes. Mammoths were relatives of elephants. They lived around North America 4000 years ago. They could not survive because of the climate change. Dodo birds lived on an island called Mauritius. They were flightless birds. When humans arrived on the island, they hunted them and destroyed their habitat, so dodo birds died out in the 17th century. Steller's sea cows were huge sea mammals. They could grow up to 9 metres long. They lived in the Pacific Ocean. They were overhunted for their skins. They became extinct abou 250 years ago. Tasmanian tigers were large wild animals with black stripes on their brown bodies. They could grow up to 2 metres in length, and they had powerful jaws. They died out in the 1930 Planet Earth is home to wonderful wildlife, however, it is clear that thousands of species ar in danger of disappearing forever in the coming decades. Comprehension​