Dinosaurs used to be the overlord on the earth, but now, their status has been replaced by various mammals, so once dinosaurs come back to life, it will be a terrible problem. When alien species come to a new environment, if they are adaptable, they will inevitably affect the local area and even threaten the interests of mankind. If dinosaurs are resurrected, they are not alien species in space, but in time. Their return will inevitably have an impact on today's species. The key is whether they are big or not. If they are really like Jurassic Park, then this is a species invasion! Imagine if there were groups of deinonychus on the African grassland, it would be quite scary!