Gobi Desert in Mongolia and California's Central Valley in the USA are the two greatest reserves of dinosaurs bones and skeletons. Millions of years ago, the present territory of Mongolia was moist and warm, and had dense forests and jungles. Dinosaurs have been living on earth for 160 millions of years and disappeared 65 millions of years ago, while their population kept increasing. Scientists are not able to precisely explain why they disappeared and can only imagine several hypotheses.
But men know that these huge animals once lived on their planet. During these past 150 years, they discovered fossilised remains. Today, hundreds of species of dinosaurs are identified all over the world. In the 1920's, an American team of scientists led by R. Andrew found the most famous reserve of dinosaurs bones in Gobi Desert. They can be seen at the Natural History Museum of New York.
You can also see many artefacts of dinosaurs bones that have been found in Mongolia in other museums, like at Saint Petersburg, Warsaw, and of course Ulan Bator.