Building the Dragon
Part I (Part II is here)
Everybody loves dragons. And while wingless ones built along the lines of Komodo dragons or alligators can be a viable part of your fantasy ecosystem, let’s admit it. We want them up in the air and breathing fire or electricity or something fun.
A quick survey of existing flying creatures: the flying fox can get as large as 2.5 to 3 pounds and a wingspan of nearly four feet. The harpy eagle‘s wingspan can be 6 to 6.5 feet and they top out at 20 pounds or so.
Mind you, I would not want to meet a 20-pound dragon with a 6.5-foot wingspan, or be on the wrong side of its talons. And a hero would look really bad-ass when his pet swooped down to land on his (steel-reinforced) falconing glove.
In green, the Quetzalcoatlus northropi, with a human for comparison. Modified from a diagram featured in Witton and Naish (2008).
Let’s aim higher.
Quetzalcoatlus is the largest flying dinosaur discovered so far. Estimates vary, but it seems safe to assume a wingspan of 30 to 35 feet (9-10.5 m). Weight estimates have varied from as light as 150 to over a thousand pounds (68-453+ kg) (in a 2010 estimate generated mathematically). The first question is, of course, can this creature get into the air? Ostriches are the only current birds of similar weight — and they top out at 300 pounds.
Will it fly?
The issue was addressed by Witton and Habib in a 2010 paper on giant pterosaur flight dynamics. Their analysis of existing fossils and reconstructions of musculature led to some interesting possibilities. For their analysis, they settled on a Quetzalcoatlus of 32-36 foot (10-11 m) wingspan and 400-550 pound (180-250 kg) weight. Witton and Habib assert that these giant pterosaurs had sufficient bone strength and muscle for flying — with some mild caveats.
- Assisted launching. The pterosaurs may have launched themselves with a strong jump followed by vigorous flapping. You can find a wide variety of birds using this strategy, especially larger ones like eagles. Others have suggested that pterosaurs may have used the running-start approach to launch or jumped off cliffs to get that initial burst of speed. Witton and Habib lean toward the jumping method, though.
- Soaring. Rather than flapping constantly, pterosaurs may have done most of their flying by finding thermals and winds to soar on. Albatrosses and vultures do this a lot — it saves a great deal of energy, and when you’re big you need to save energy.
- Moving on land. Pterosaurs were not built for it. But the authors theorize that they may have been able to get about by hopping/jumping (saltation, as sparrows do) and possibly bipedal walking (many birds do this — ducks, robins, hawks…).
What does it eat?
Witton and Naish wrote a 2008 paper on morphology, in which they addressed some of the questions of the morphology and ecology of giant pterosaurs, including Quetzalcoatlus. It’s good reference material, but chances are you aren’t building a dragon with a stork-like beak and a neck that’s long like a stork but less flexible — like a lizard. They lay out some reasonable options for such creatures, but a traditional dragon with a shorter muzzle, teeth, and greater neck flexibility will have more predatory options.
Bearing in mind the three rules of predators as formulated by me (and only me): 1. Don’t get hurt. 2. Don’t work too hard. 3. If it gets you food, do it. Also bear in mind that while an earth-bound predator can gorge on a kill and then slink away to digest, a flying predator can’t eat so much at once that he can’t fly away if threatened. Many small meals throughout the day are probably the best strategy.
- Fishing. This is a perfectly good way to acquire a relatively large amount of calories with a reasonable amount of work. Given the general structure of a Quetzalcoatlus-based dragon, I would think that divebomb-style fishing (as done by ospreys and eagles) could work.
- Carrion. It’s not glamorous, but it fulfills rules 2 and 3.
- Traditional airborne hunting. This could be hunting birds, other dragons, or earth-bound prey, as falcons and hawks do. But bear in mind the stipulation about over-eating and the fact that it’s easier for a rabbit to hide in a forest than for a fish to hide in a lake. Hunting animals that congregate in large groups in meadows (or other open terrain) will make hunting easier… but also remember that we’re talking about a 30-foot wingspan dragon blotting out the sun. It’s difficult to miss that flying overhead, one would think. Or can you find a work-around for that?
Will it breathe fire?
Scientifically, the problem with breathing fire has always been the question why does it need to? Anne McCaffrey came up with one of the best answers (we bred them to do it) but in strict ecological terms, teeth and talons are quite sufficient for all your hunting needs. And if a feature isn’t useful to a creature’s survival, it isn’t done. Right?
Well, except for things that the opposite sex finds attractive. Such as peacock tails, silly dances, and the ability to compose sonnets.
Your mission, should you choose to accept it: imagine fire-breathing (or lightning bolts, what-have-you) as a mating display. We will get back to this in Part 2.
Fire = Mating display = Clever!
I suppose it makes more sense than as a weapon, unless dragons like their meals really well done.
I mean, an animal on fire would probably be running around in panic starting forest fires or jumping in the nearest stream.
Have you heard of / read ‘Flight of Dragons’, by Peter Dickenson? He proposes that dragon flew due to a kind of honeycomb structure inside them that they could fill with hydrogen gas, and expand. The gas came from limestone which they ate and dissolved, and meant their insides were full of hydrochloric acid. When they wanted to land, they would expell the gas by burning it off. Flight, fire and corrosive blood, all explained! Also, due to them being full of hydrochloric gas, when they died their bones were dissolved. So, no skeletons or fossils.
Dickenson’s theories on dragons were used in the animated film ‘The Flight of Dragons’ (although the story came mostly from George R. Dickenson’s ‘The George and the Dragon’).
That is a really cool theory! I will have to look that book up – it will be interesting to see how he handles the hydrochloric acid being contained and whether they had to eat limestone every time they flew or if they had a store of it in another stomach.
The only theoretical reason that came to mind for belching something, aside from mating (which is an interesting concept), would be self defense. Dragons, which in my mind are traditionally large and fearsome, were also usually solitary and usually cumbersome. So, assuming a slower take-off, and the ability of humans/natural foes/other dragons to mass an assault against a dragon, there is the possibility that size and fierceness alone would not protect them until take-off or from a many fronted assault. Having a “long-range” weapon such as fire-breathing could keep attackers at a safe distance (this is until the beginning of most modern weaponry) which would protect the dragon until it could fly off or deal with the close attacks that got through.
Still, awesome article! I am really looking forward to the next part!
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Great article! Thank you. Parenthetically I see the hydrogen flotation idea a lot of places but don’t think the math/physiology works. A cubic meter of H2 can loft a little over a kilo. You can imagine a cubic meter of critter is a whole lot more, so the hydrogen bladder would have to be huge—maybe cubic meters—and a huge liability in a fight with another fire-breather! Maybe that’s a reason to breathe fire, but more so I think its use as a standoff weapon easily wielded against multiple targets versus a one-on-one fight, and perhaps to lay waste to human settlements.
Hydrogen would also be unwieldy for making fire because it quickly rise and unless mixed carefully with oxygen burns off slowly (look at the Hindenberg). Alternatively with the right mix ratio it explodes instantly. I’m thinking of something more like acetylene, C2H2, which is carbon-based and, with a good oxygen mix, supports a very hot flame. Plus it burns with a beautiful, sooty flame—hydrogen fire is colorless (the Hindenberg’s skin provided the color—consider the Space Shuttle SSME’s instead). These are details I’m debating in a novel I’m writing, where strict science is not required but adds something….
How does the critter fly? I like the idea of light construction, muscles able to metabolize energy very effectively per kilo, and ultra-low-energy soaring techniques like the albatross. It might work….