What is a danasours?

It seems like there might be a typo in your question. If you meant "dinosaurs," they were a diverse group of reptiles that thrived during the Mesozoic Era, approximately 230 to 65 million years ago. Dinosaurs varied greatly in size and shape, ranging from small, bird-like creatures to massive, long-necked giants. They were the dominant terrestrial vertebrates until a mass extinction event led to their extinction, with some descendants evolving into modern birds. If "danasours" refers to something else, please provide more context!