Just my opinion, but I think that way back then, in ancient times, they had the technology to cross breed and mate animals in such a way as to create dinosaurs, and over time, the technology was lost due to natural disasters, floods, earthquakes, and so on. Dinosaurs were NOT a natural development like deer, cats, dogs, birds, etc. They were something unnatural created through the abuse of technology. So what killed the dinosaurs? Earth changes, floods, earthquakes, volcanoes, and the like. Just my two cents. Wouldn’t both me if people strongly disagree!