However, Daenerys isn’t an expert on dragon biology. (Nobody is.) Real reptiles can be difficult to sex, particularly when juvenile. Males keep their genitalia inside their bodies until needed. So who knows, maybe she’ll end up having to change the names of one or more of the dragons.
Yeah, gotta have a female dragon or the whole thing is for naught. Of course, I wouldn’t put it past GRRM/the producers to end the whole series with “Rocks fall - everyone dies.”
Maybe Dany loses some power when one of the dragons turns out to be female and the other two battle over breeding rights, depriving Dany of their use during a key battle.
These dragons are neither reliables nor invulnerables. A hand thrown spear was sufficient to wound one. A mere ballista could probably kill one. Although I don’t expect them to be downed by medieval artillery. Not dramatic enough.
A hand-thrown spear was able to wound a young one. We have no idea how tough they are now.
Here’s Drogon as he was when he was injured by a spear. Here he is now. (Another view.) He’s at least three times the size he was before. He’s not vulnerable to spears anymore (unless one is lucky enough to hit him in the eye.)
Since we’re talking dragons, and this is the Dope, has anyone else noticed that the “dragons” are actually wyverns?
A lot of people have noticed that they only have two legs. On the other hand, they breathe fire. So the correspondence to Earthly mythology leans more to the “dragon” side.
Conclusively, the people of the show world call them dragons.
Good point. If there are any books on dragon keeping left the Citadel (which is conveniently located in Tyrell territory) probably has them.
Despite this being a fantasy world and not bound by the rules of evolution, the dragons are more plausible from the point of view of vertebrate anatomy than dragons with four legs and two wings would be. On the other hand, nothing that big could fly in a world with Earthlike atmosphere and gravity. And the fire-breathing would be an innovation as well.
I surmised in the predictions thread that at least one of them will definitely die before the series ends (probably Drogon, since he’s the only one with any characterization, and has the closest bond with Dany). If she loses her war, I could see all three of them dying. If she wins, the other two may live and carry on. If they mate that might surprise everyone.
So if Drogon is a female, what does she call her? Dragon or Drogan? 
It seems to me that the designers of the dragons were heavily influenced by current ideas about Pterosaurs. Some of which were pretty large. Not as large as the dragons in the show, which I agree are probably bigger than realistically possible, but still impressively big.
I’d like to see Drogon die and be resurrected by the Night King. The dead horses of the White Walkers have already shown us that his ability isn’t restricted to humans.
It especially annoyed me to see the dragons hovering above the flaming ship. Physics, GoT, it’s a thing.
Also, resolved: Jon Snow’s death was an extremely lame cliffhanger and excuse to release him from the Night’s Watch oath and everything that follows from that is only shoehorning it into the story to maintain some semblance of internal consistency.
Shooting jets of fire? Totally okay. Hovering? Nonsense!
If you want to nit pick physics at all, a Dragon that looked like that would probably never even get off the ground unless it had the density of paper mache. Magic lets them fly. Magic lets them hover.
It’s not magic that lets dragons fly, it’s wings. Gliding is far more believable than hovering.
I’m not going to nitpick the “fact” that dragons breath fire, but that brings up another point I neglected to mention, which is that it should take them a while to recharge. Expending the amount of energy needed to (implicitly) burn that entire fleet in such a short time isn’t believable either, unless they fuse the atom internally.
They burned one ship, Dany needed the fleet.