There is no doubt that dinosaurs once lived on Earth and in certain places seem to have been numerous. Paleontologists have found evidence of their existence in sediments from all continents, including Antarctica and have found evidence that includes bones, eggs, nests, and footprints. Were all dinosaurs large? The study of dinosaur bones, eggs and footprints provides valuable information about their size, physiology, social behaviour, and habitat. While dinosaurs are known to be the largest land animals to have inhabited the planet not all dinosaurs were giants. Some species were small, similar in size to a sheep or dog.