If the devil has a thorough understanding of life and development, would it not be possible for him to manipulate the parts of organism and thereby generate new forms of life? (Dinosaurs? Large insects? And so on?) Monsters? What for? Perhaps to mock God. Perhaps to wage war against other living things, or... could it be, even human beings? There is so much we do not know about what happened at the beginning, and the consequences of the rebellion of the demons on the material universe.
While the devil cannot create ex nihilo, if there is a natural mechanism by which new species/body types can be generated from pre-existing ones, then cannot the devil by his power to act upon bodies and move them cause the same effects?