We may all have some familiarity with winged skulls - from Avenged Sevenfold's album covers to bikie shirts. However, for my science-fiction/horror story, I am curious about how these creatures would actually evolve and develop.

Body Parts

  • These creatures would simply be skulls (around the size of a human skull - although it doesn't necessarily have to be a human skull) with wings attached to their back, and potentially a tail running perpendicular in-between the wings for balance and control during flight. They would have limited muscle and flesh, aside from tendons controlling the jaw, their wings, and tail (depending on what popular opinion says, I may close off the bottom of the skulls either with bone or flesh).


  • All other organs would be internal, stored where the brain would be. As such, their brain will be smaller, and their lungs, stomach, and other organs would have to be quite small too.


  • Due to having no legs, and as such lacking an ability to land, these creatures would have to be perpetually in flight. As such, I am thinking of these skulls' habitat being around lava lakes and volcanoes, where the hot convection currents of gas could keep them afloat.

Diet and Reproduction

  • I would definitely prefer these creatures to be carnivorous, and not be afraid to attack a human explorer through biting their flesh off them. Aside from that, they could also attack insects, birds and other animals on the ground.

  • Regarding reproduction, due to the difficulty in physical reproduction between these species, I believe releasing spores/sperm and eggs is the best way to go. A female could also release eggs, and a male could fly past and fertilize them.

With all of these conditions in mind, how could such a creature evolve?

  • $\begingroup$ I love questions like this :) in the past I wrote about beings that resemble heads. Flying ones are more challenging, but that's what's fun about this site. $\endgroup$ Commented Mar 28, 2020 at 8:24
  • $\begingroup$ If they are permanent fliers they will not attack humans. Any prey that might cause them to crash to the ground will be avoided, so no fly-by's where they rip some flesh of a human. A way around this is to increase mobility on the ground. Perhaps the wings can push the skull around, or there are some legs hidden behind the chin while in flight that extend when on the ground. Even so prey will be airborne most of the time as the skull can only bite in front of it and has little way of manipulating itself or dead prey for easy feeding. Better snatch insects and small birds out of the sky. $\endgroup$
    – Demigan
    Commented Mar 28, 2020 at 12:22

3 Answers 3


Although it sounds fantastical, the interesting thing is weirder animals have evolved than what you describe that exist or have existed.

There is enormous variety in life. We have starfish, we have octopuses, we have Cambrian era exoskeletal animals.

Evolution is the gradual result of many, many layered mutations over a very long time. The important principle is that there is no goal in evolution - each gradual step is an optimisation/random mutation that makes evolutionary sense at that time.

So for your flying skulls you need to consider that at every step of the way, each evolutionary change must make sense and be an advantage at the time (or the place) it was made.

Let's have a look at some possible scenarios to result in your flying skulls:

  1. First, you need to start with an animal - the easiest is either a bird or bat. They already have the structure and beginnings of what you require. Bat wings use elongated fingers with stretched skin for flight, whereas birds use the entire arm for feathers. Your final fertilisation technique favours birds, as they already lay eggs.
  2. There needs to be a scenario where bodies become less important, and the spinal column shrinks. This could be:
    • An increase in social requirements through Sexual Selection. The brain requires an increase in size to obtain superiority in more complex mating procedures and defence against rival males / females.
    • The increase in brain size also comes with an increased weight penalty, and thus reducing mass of the body may be required to offset increased brain size
    • Stability is not too much of an issue now, as bird tails for flight have uses. Perhaps the environment changes to trees and short flight scenarios where lengthy flight is not required - this seems to correlate with increased social structure happening in smaller environments.
  3. The spinal column, once shrinked needs to then disappear almost completely, and organs moved to inside the skull
    • Again, sexual selection is your friend here. Perhaps there is more protection by incorporating vital organs within your skull, so mates are chosen that appear to have this advantage.
    • Natural selection could also favour stronger 'exoskeletal' structures with organs located within skulls, with those that don't not surviving.

Your flying skulls are thus evolved. It is important to note that residual structures would still exist - after all we have all evolved from fish so our embryos would form still like fish, just in later gestational periods the spinal column would be less and less important such that (like an appendix) it remains there in a redundant form at the back of the 'skull'.

For look and appearance these are mainly Sexual Selection traits. Humanoid skulls with bilateral symmetry and humanoid features could be desirable from sexual attractiveness throughout.

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    $\begingroup$ The problem is that long flight scenarios are required - remember, these things have no legs to land with, and cannot move on the ground. Additionally, I feel like feathers wouldn't fare well in such a hot environment - I was leaning more towards scaled-like wings. $\endgroup$
    – bio
    Commented Mar 28, 2020 at 4:08
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    $\begingroup$ @bio Continuous flight is difficult to sustain - remember energy use is vital to flying creatures. As you mention perhaps buoyant environments are more suitable then, however they still need to land - perhaps their wings become their support structures on land (like legs) to allow landing and movement. It is possible for membrane-like structures to form between arm bones as opposed to feathers if it is advantageous - this may indeed reduce reliance on feathers. What do you mean when you mention 'scaled-like' wings? Sounds very heavy. $\endgroup$
    – flox
    Commented Mar 28, 2020 at 4:38
  • $\begingroup$ by scale-like wings I did mean membrane-filled wings - I was thinking of dragon-like wings, or lizard frills, and couldn't find the proper word, so my mind went to scales. $\endgroup$
    – bio
    Commented Mar 28, 2020 at 5:02
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    $\begingroup$ Also apparently it turns out some birds can fly almost indefinitely: smartenings.com/3-amazing-birds-that-never-land $\endgroup$
    – bio
    Commented Mar 28, 2020 at 11:27

I'd suggest starting with a bat, for three reasons:

  1. Flying around constantly is very, very difficult. There are only a handful of animals that do it, and all are birds that are completely constructed for it, with enormous gliding wings and aerodynamic bodies. Skulls are not aerodynamic. However, bats already have tiny, easily-hidden legs, which can barely walk, but can be used to hang upside down from ceilings. This seems like a better option than continuous flight.
  2. Most flying skulls in fantasy are pretty bat-like anyway, with flappy erratic flight and squeaky noises.

  3. One of the most distinctive features of a skull are the large, empty eye sockets, and it's hard to create real eyes that look like empty eye sockets. However, bats already have large, empty sockets on their head - their ears. If you look at a human skull head-on and imagine its eyes as a bat's ears and the nose as the bat's dark face, it isn't hard to imagine that a slightly modified bat, flying towards you in the dark, could be mistaken for a flying human skull. You don't even need to remove the legs - the spindly legs of a bat could appear to be fangs extending down from the body, making it even more terrifying!

Of course, even if you imagine the ears and face as the skull's eyes and nose, a bat still doesn't look that much like a skull, because a skull also has a big round head behind it. To explain this, let's say that this is a bat that has a large, inflatable "pouch" on the back of its head. Inflatable pouches aren't an uncommon feature in animals - it can be used as both a threat display or for mating purposes, or to create loud, deep calls.

So this particular bat has a white back-pouch and a white body, with black ears and a black face. It is also more aggressive than most bats, and will dive-bomb intruders who venture near its cave, flaring out its pouch threateningly. With its ears and face silhouetted against its pouch and body, it could look very skull-like head-on and an unfortunate human who happens to wander into its cave could very easily report being attacked by a swarm of flying, screaming, fanged human skulls.


I think I would make this something that LOOKED like a skull, but wasn't really. More like a flying turtle with a spring-loaded jaw or fused lower legs (with claws evolving into 'teeth') capable of delivering a lethal bite/chomp. Let's say these operate in packs. Each bite may not kill an animal, but a dozen attacking a deer, say would lead to disabling wounds or lethal blood loss. Wings can be used like legs, so that is less an issue than it sounds like (some birds even had four wings). A groove on the body ('neck'?) to shelter wings would allow the skull to be kicked around some and not be killed or crippled. I agree a bat or bird would be the starting organism. The appearance may have evolved as a coincidence of function, or like the Japanese crabs resembling dead samurai, they were selected because of people's horror at eating something that looked like a human. They don't have to be good fliers. Nocturnal might allow them to sneak up on prey and just be way cooler.


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