Recently I have given myself an interesting challenge: To create an interesting fantasy world that does not have conventional "magic."
In this setting I'm writing, our entire civilization has collapsed in the year 2232 thanks to pressures caused by climate change. 99.7% of the world's population dies out, with the surviving humans returning to a hunter-gatherer lifestyle for thousands of years. Eventually, new settled civilizations do develop in a similar manner to our own world. Most of the world by the time of the story has entered the late iron age. These civilizations have lost most of the knowledge that the "ancients" once had and are basically starting over from nothing.In essence, this setting has the same physics as our own world.
In the story, there is a scene where one of the characters is attacked by a "dragon." This "dragon" cannot be an illusion, hologram, or illusion of any kind, as the character in question physically reacts to it. For the purpose of the story, the dragon has to be a "dragon." Not a plane, drone, or anything else that the characters could mistake for a dragon. The dragon has the following properties:
Although it does not have to be strictly "biological," it still has to be self-replicating and has to perform all of the functions a biological organism would have to do to survive. "Eating, drinking sleeping, etc."
It has a wingspan of 17 meters, weighs 200 kilograms, and is 7 meters long.
It does not have to be sentient. However, it must have a basic sense of self-preservation that all animals have.
It cannot be a one-off deal. There have to be multiple of them that have a stable population.
It does not have to be able to "breath fire" per-say. But it must have the ability to emit a defensive projectile from its mouth that is dangerous to humans
With all of that being said:
Would such a thing even be possible with 210 years of technological advancements?
For what purpose would the "ancients" create such beings? Why would they create them in such a way as to require them to perform the basic biological functions of organic life, and what about them has allowed them to survive for so many centuries after the demise of their creators?
Would a creature with the given physical specs actually have the ability to maintain powered flight? Why or why not?
If any of the above is physically impossible; what would be a reasonable alternative?