Young Writers Society

So here's the deal: I finally worked out wyvern anatomy. I can't work out the aerodynamics, but since they are essentially wind elementals in my world I attribute it to air magic, alright? Great.

In my world, wyverns are like dragons but two-legged. Here is how I was thinking I could make their anatomy pretty much work for a flying, carnivorous lizard:

- Give them bird anatomy: hollow(ish) bones, air sacs, high metabolism, etc.

- Except for their wings, heads, and tails, that is. They have bat-like wings (this may be changed because I need to look deeper into how bat wings work), draconic heads/necks, and draconic tails.

- Body covering: traditionally this is scale, but in my world I made it would be down with a covering of something in between a feather and a scale (all a feather is is an evolved scale, anyways).

- Why wings if not to fly? Well, here it is: they use wings to a) scare off predators; b) thermoregulate by vasodilating the blood vessels within the wing while in the sun to warm up or when dipping them in water to cool down; c) attract mates and use them as displays like peacocks do tails; d) use the thumb on their wings as a foreleg or occasionally a weapon; e) to scare predators by making them appear larger than they are.

- Cold- or warm-blooded? Still something that needs some work. I think I have to make them warm-blooded endotherms- otherwise flying at such great heights and being able to withstand a variety of climates is nigh impossible.

- Eyelids situation: they have eyelids and a nictitiating membrane like a bird. They need this to protect their eye in flight, when hunting, etc.

- What's up with the tail? Well, it's a wyvern so it gets a draconic tail. It doesn't exactly fit, but....it's fantasy, okay?

- Toe configuration: like owls, they can switch between the two-forward/two-back toe configuration and the three-forward/one-back to configuration. They do have a larger hallux like a bird of prey would.

- Food Chain: They would be like a hawk- an apex predator that is still prey to certain species. They would eat small rocs and be eaten by larger wyverns or dragons. Of course, there is more to that, just listing off all the species in their plane would get ridiculous.

If there is anything else that needs clarifying, please ask.

So here is the question: do you see any flaws or things I missed that need some working out? If so, do you have any solutions?

Thanks to anyone who answers this,

Feather

I remember this one game where the dragons and wyverns all had a few vacuum like things in their head and wings that pressurized air and fire it out of the bottom of their wings in order to help them boost around. That might give you a new use for the wings, since it sounds like you're not sure what to use them for.

Sorry if I miss-understood!

Other then that this all makes sense to me.

Anything works especially in a fantasy world. There were "flying" dinosaurs, so dragons/wyverns aren't too illogical. I see how you're trying to make the flying dragons you're talking about seem more realistic, but really...nothing flies like the birds. The only thing about this idea that requires a large amount of thought is the flight aspect, anything else you can get from dragon legends.

Remember, in fantasy, anything is possible. Including huge flying reptiles.

Considering it's fantasy, I think you're safe no matter what you choose, because at some point you'll always hit the "the impossible part is explained by magic / suspension of disbelief." In a SF, the characters actually talk technobabble more than they would in a fantasy, so you might need a convincing spiel, but for a straight up fantasy I imagine most of these details is for behind-the-scenes info and your own benefit as the author.

Sounds like what you're trying to do is bird-reptiles. You might want to think about whether they're meant to be closer to birds, closer to reptiles, or more ancient like the flying dinosaurs which are basically a combo/predecessor.

Pneumatic bones are mainly the humerus and femur and sometimes some others (and maybe one major one I'm forgetting)--not *all* the bones are "hollow." It's actually an extension of the air sac itself into the bone. The respiratory system is really important, as you've noted, for being lightweight but also for being super efficient. Because of this, birds are *extremely* susceptible to respiratory irritants, toxins, and infections, so if your wyverns have the same setup, they will too. They're so efficient at getting the oxygen out of the air, they're equally efficient at getting all the other crap out of it too. Another anatomical thing you didn't mention is the skeletal structure--namely, birds have a keel, HUGE pectoral muscles to support the wings, and a lot of fused vertebrae to support the spine. They also use a syrinx to make noise, as opposed to a larynx, which is toootally different anatomically. Their digestive system is very different, too, as is their reproductive system, but I think it's more similar between birds & reptiles than either one to mammals. They're both egg-layers, for example, and have a vent/cloaca.

The only actual problem I see is that vasodilation causes cooling because it disperses heat. Especially if they're vasodilating they're *wings*, which are peripheral. To conserve heat, they would vasoconstrict their wings, so the blood flow is directed more towards their core body systems. For example dolphin dorsal fins have veins that vasodilate to help cool them down as the water runs over it. Being in the sun is probably not a big enough heat source to reverse it to counter-intuitively warm them up.

@Megrim: Ah, I see the thing about the vasodilation. I'll fix that. I know this is fantasy, but I like getting things as realistic as possible, so...

Also, are you a bird nerd? Because that spiel sounds a lot like something I would say.

I guess? A little?

Sounds like more than a little....