Reading through the internet and countless questions here, I learned that most Earth’s flying animals have beaks because they are lightweight and function well as a substitute to hands.

Now, would it make any evolutionary sense that in my world there are sharp-teeth flying predators?


  • I want altitude flying, as high as peregrine falcons or vultures (so bat-like creatures are discarded because as far as I know they only fly at low altitudes);

  • EDIT 2: There was some discussion on the definition of "flying" and "gliding". To simplify, I don't want my creatures to "glide" like sugar gliders or glider lizards, but rather as prey or carrion birds;

  • Not beaks with teeth as some birds on Earth. Actual well defined jaw bones, like most predator mammals or crocodiles;

  • Quite large creature, but not trespassing the limits of weight of flying creatures of our current real world physics;

Bonus points if the reasons of it being possible fits a scaled animal rather than feathered.

Atmosphere and physics is Earth-like. Biological structures are also Earth-like. General anatomy and appearance can be discarded for now, let’s focus on the teeth problem.

Also, I did a quick search here to see if this is duplicate but couldn’t really find one that fits my needs. Feel free to mark it as duplicate and link the answer that you think that solves this.

EDIT: For a time parameter consider today's Earth period.

EDIT 3: I'm creating this world's flora and fauna from scratch so stuff like great extinction events and selective pressure can be manipulated to match what I need.

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    $\begingroup$ I think the main restriction you'll be fighting is balance. Most birds have small heads - less weight at the front and their centre of mass is very...central. Teeth need strong jaws, jaws need muscles. All this mass you put towards the head the more mass you need to pile on the tail end (or longer tail) in order to balance yourself about the wings so your "bird" can put more effort into flying and less into stopping itself from tumbling. $\endgroup$ Commented Feb 6, 2017 at 11:40
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    $\begingroup$ Google this critter: Anurognathids. $\endgroup$
    – cobaltduck
    Commented Feb 6, 2017 at 14:40
  • $\begingroup$ @cobaltduck wow never heard of them before, really cool. $\endgroup$
    – rschpdr
    Commented Feb 6, 2017 at 15:33
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    $\begingroup$ SOme toothed pterosaurs got quite large, see Coloborhynchus and Tropeognathus $\endgroup$
    – John
    Commented Feb 6, 2017 at 15:52
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    $\begingroup$ There is no meaningful evolutionary distinction between "Earth's 18th century" and "present-day Earth", unless of course you mean the 18th century after the formation of Earth, at which point almost no matter which definition of "formation" you use you are looking at a dead, molten ball of lava. $\endgroup$
    – user
    Commented Feb 6, 2017 at 16:25

7 Answers 7


The evolutionary "reason" for beaks would seem to be that they're aerodynamic, and they save weight by combining the jaw and the cutting / gripping function into a single structure. But flying creatures would have teeth if the trade-off was worth it.

The function of teeth is to cut, tear and grind food, which is important if your prey is large(ish) compared to your own body; a lion couldn't swallow a gazelle whole, or if it did (like a python) it wouldn't be very mobile after eating. You can have a serrated beak, but the "teeth" can't be very big, because a beak with shark-sized teeth would already be blunt by the time it was full grown; an adult shark can replace its teeth by growing sharp new ones.

Birds that eat relatively large prey have different strategies for dealing with that. If you watch a big bird eating meat, it's all tearing and whipping things around with their head, which is inefficient compared to using teeth. But because they're so mobile, they can take their prey somewhere quiet and take as long as they need, and perhaps let it rot to make it easier to chew (many birds of prey are carrion eaters). Also, birds of prey often focus on fish as those are generally less well-armored.

More broadly (and obviously), flying creatures prefer flying to fighting. They're inherently more fragile, but better at escaping danger. You don't need to bite a lamb's throat out if you can drop it 3,000 feet onto a rock, and if you can kill anything that comes near you, you don't need to be able to fly away from anything.

So I guess the environmental niche you're looking for is one where you need to eat fast and/or fight large prey on the ground, but also there's an advantage to flying (e.g. prey is very widely dispersed). Maybe a large, barren mountainous region, but there are sheltered migration routes running through it? Partly collapsed lava tubes or heavily wooded gorges or something, which can support prey but don't have room for a mountain lion to make a lair.


I want altitude flying, as high as peregrine falcons or vultures (so bat-like creatures are discarded because as far as I know they only fly at low altitudes);

Real flying, not gliding;

There's a misconception here about flying.

Most of real flying is gliding.

Any creature flying does as little work as possible when in the air. They glide. They use air currents. Seagulls and other large avians are fine examples.

Gliding, contrary to what you may think, does allow you to rise very high. The world altitude record is, I think, some 15 km (that, 15000 meters).

The main limitation for altitude in normal atmospheres would be that the density of the atmosphere will decrease, making it likely that a creature flying that high would need to build up and store whatever it breathes and could only stay at such heights for relatively short periods.

But gliding is the heart of flying.

Flapping your wings is not a good plan, anymore than a ground creature would survive long running everywhere. It's energy inefficient. It's for getting off the ground (at a run usually) and redirecting your flight with occasional bursts if you absolutely have to stay up.

Not beaks with teeth as some birds on Earth. Actual well defined jaw bones, like most predator mammals or crocodiles;

A beak with teeth is just as effective for a predator as a well defined jaw bone. A lot of razor sharp small teeth backed up by a long hard pointy stabbing object like a beak is a pretty vicious combination.

Part of the beak shape is for aerodynamic effect. A well defined jaw is a heavy object with little practical use for flight control. The more your creature relies on bite (which is implied for such a design), the more muscle they need in the jaw and weight is last thing an avian design needs.

But if you insist in such a thing, go ahead. It's not written in stone that an avian creature has to have a beak.

If you'd ever seen an eagle, those feet-claws are pretty deadly - I saw one attack a large loon in a lake one time and believe me, feathers and a beak are no hindrance to being a predator !

Quite large creature, but not trespassing the limits of weight of flying creatures of our current real world physics;

Like a large glider than can reach 10km in altitude and glide a distance of 1000km ?

Sounds fine to me.

You really need to read up on gliding to develop this idea properly, IMO.

But consider - what advantage or practical evolutionary niche is gliding or flying very high giving your creature ?

Bonus points if the reasons of it being possible fits a scaled animal rather than feathered.

Feathers are useful for control surfaces and insulation (cold at altitude and fat may work for ground creatures, but it's too heavy for avians to use much).

Scales are fine for armor, but they're heavy (have to glide and lift into the air). It's worth noting that your basic avian predator is hardly likely to benefit from scales. They have the ability to limit their exposure to attacks from ground creatures and they can hunt in small groups (like many modern predators). Even a family or clan sized unit would be a dangerous combination for a ground creature.

I think scales are not needed. A reasonably tough skin would be fine.

  • $\begingroup$ With "gliding" I meant sugar gliders and glider lizards. I'm aware that most flying is gliding, but the animals above can't even "fly" past a tree's height. They use their gliding structures only to hop from tree to tree (please correct me if I'm wrong). Anyway, great answer, thank you! $\endgroup$
    – rschpdr
    Commented Feb 6, 2017 at 12:33
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    $\begingroup$ Large seabirds are excellent examples of large gliding creatures. No one would say that a large seagull is either not a formidable opponent or was not able to travel large distances. Would you say an eagle only flew from tree to tree ? No, they soar ! I'd suggest widening your concept a little. $\endgroup$ Commented Feb 6, 2017 at 14:32
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    $\begingroup$ I think you completely misunderstood what @resch meant with "glider". As resch mentioned in the comment, the word "glider" was intended for creatures whom cannot engage in powered flight, but instead only can engage in controlled falling. That is, even though birds such as seagull, eagle, and albatross use gliding as a way to conserve energy when flying, they can still flap their wings to get off ground, as opposed to e.g., flying squirrels, flying fish, and gliding frogs, which cannot flap any wings to gain any significant height. $\endgroup$
    – Mrkvička
    Commented Feb 6, 2017 at 16:49
  • $\begingroup$ @Mrkvička Thanks, I clarified in the question (at least I hope I did). $\endgroup$
    – rschpdr
    Commented Feb 6, 2017 at 16:52

Short answer: yes, you can. There have been many species of flying, scaly, toothed reptiles on Earth (pterosaurs). Not all of them had teeth and many apparently had some hair-like fluff, but that's optional. For aerodynamic reasons a flying creature will probably evolve towards having a pointed snout, or very narrow jaws, or a beak, but there are ways to compensate. In any case, a beak need not be a fragile thing.


Yes and no

There's no reason why not, apart from the fact that beaks became dominant to the point of exclusion for a reason.

To have a toothed flyer your world could be at a much earlier stage of an evolutionary cycle, perhaps not long after a mass extinction event when there were a lot of broad niches to be refilled and a lower pressure to be perfectly optimised. It may not be a particularly efficient flyer, but it can fly. Size wise, that's a question for consideration but a mating tendency towards "biggest and strongest" could make for a big creature.

In the long run the efficiency and lighter weight of the beaked flyers would likely come to dominate and displace your overweight creatures.

  • $\begingroup$ Nice, forgot to tell evolutionary era. Will update the question. Thanks for the answer! $\endgroup$
    – rschpdr
    Commented Feb 6, 2017 at 11:46

It is obviously possible. There were pterasaurs that reached extraordinary size and used teeth. Some types of flying dinosaurs were larger than any currently living bird.

Teeth are better for eating large prey and for fighting. Size becomes a problem for flyers because weight goes up dramatically as size increases by only a little bit. At some point, you have severe limits on what can get off the ground using muscle power alone.

So, let's think a little bit: we have a very large animal with teeth. It might hunt for reasonably large prey like (say) deer. It can fly, but obviously, when you consume quite a few pounds of venison, you are going to be a lot less mobile. As stated earlier, large raptors like to take large prey up to a high place where they will be left alone long enough to tear it up with their less than efficient beak. Let's say our large flyer lives in a place with plenty of reason to fly, but few or no good options for perching way out of reach. I think of maybe some of the crazy steep hills of Southeast Asia and China. No trees big enough to eat in, just hilltops where scavengers might come in and try to steal your prey, and ravines and gullies that make a lot of sense to fly over. This would be good mountain goat country, so there's your prey. Figure there are smaller scavengers/hunters like jackals or coyotes that it needs teeth to fend off, and you have a reasonable scenario.


Bats can be badasses.

Behold the greater noctule. http://www.mammalwatching.com/Palearctic/Images/Hungary/Nyctalus%20lasiopterus%20jmB.jpg enter image description here These bats fly high into the air at night and catch birds on long term migrations. The birds are flying blind at night and never know what hit them.


I say go with bats.


You said in your question

most Earth’s flying animals have beaks because they are lightweight

and yet you want to put a burden on the animal by loading it with a jaw. You are therefore putting your animal on a preferential route for extinction.

More weight means

  • more effort to fly
  • unbalanced flight
  • increased weight due to the structural changes needed to use the jaw (if you want to bite you need proper muscle mass to move the jaws, and more robust skull bones to support the muscles. All of this come at a weight)

and this cost has to be payed in exchange of what? I see no advantages over beak-equipped animals.

  • $\begingroup$ Coolness. Also, depending on how intelligent the creature is, there's a larger variety of sounds you can make with lips and jaw than just a beak. $\endgroup$ Commented Feb 6, 2017 at 15:24
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    $\begingroup$ @DomineSatanas Sound-wise, birds have lips and jaws beat via an organ called the syrinx, which is basically a better version of the human larynx. Birds like parrots can make most of the sounds humans are capable of producing and many we aren't. $\endgroup$
    – ckersch
    Commented Feb 6, 2017 at 16:35

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