The wyverns in my world are similar to the classical depictions of wyverns, specifically in that the two legs are attached directly under the wings' shoulders, rather than the avian form found in modern depictions

To note their other features: They are tripedal, walking on their tail and legs. Their wings are webbed and cannot be used to walk, but are used for flight. Their legs resemble a plantigrade forelimb, with 2 visible segments and a backwards-pointing elbow. The leg's attachment point is at the breast, as in lizards. They have an avian head/neck with reptilian jaws, and would have a long tail like a legless lizard. They are also carnivorous, and roughly horse-sized. They hunt like eagles, and have raptorial feet. Their skin is scaly, and has no fur or feathering

While I could use the same anatomy as in winged quadrupeds, there is also the point that these wyverns only have 4 limbs, like real tetrapodal species. However, there is still the issue that, unlike real tetrapods, the wyvern's limbs are clustered about the chest

Considering this, could normal tetrapodal anatomy (specifically regarding the torso and limb attachments) realistically be altered to form these wyverns

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    $\begingroup$ This is similar to a question you asked two months ago. Is this basically the same question avoiding the problem with creature size in the former question, or is there something materially different, here? $\endgroup$ Oct 10 '21 at 19:29
  • $\begingroup$ @JoinJBHonCodidact This question is about a creature with 2 forelimbs as wings and 2 hindlimbs as legs, and is based around realistical tetrapodal anatomy. That question is about a creature with 4 forelimbs as wings, 2 more forelimbs as forelegs, and 2 hindlimbs as hind legs. It is also based solely in aerodynamics, with no respect to anatomical realism. How can I make this clearer in the question? $\endgroup$ Oct 10 '21 at 19:41
  • $\begingroup$ @IchthysKing You've already described how the wings and legs attach to the torso of your critter, (Legs at breast, wings above the legs). I'm not sure what you're asking for since you seem to have answered your own question. $\endgroup$
    – sphennings
    Oct 11 '21 at 1:39
  • $\begingroup$ What's wrong with starting with the anatomy of a bat? You can even have larged size ones. Granted, it is gonna be a pain to make them carnivorous and predators (hard time to be maneuverable when your only "grabbing pods" are busy fine tuning the final approach ), but maybe you can make them carrion eater? $\endgroup$ Oct 11 '21 at 4:34
  • $\begingroup$ @sphennings I'm asking if that specific structure could exist as a realistic tetrapod anatomy $\endgroup$ Oct 11 '21 at 6:52

Short spine syndrome

short spine dog


Your wyverns have a much compressed spine. The pelvis abuts the rib cage. Thus it is all limbs seem to come from the chest. The chest and pelvis are essentially the same structure.

short spine skeleton


This syndrome occurs in dogs. Some are viable animals and can be good dogs.

The compression of your wyverns spine includes only the thoracic and lumbar vertebra. The cervical and sacral vertebrae are redundant and elongated, making up the long neck and tail of your creature.


I think you need two things:

  1. The spine is horizonal near the shoulders so the wings are facing the right way.
  2. The hips are vertically under the shoulders.

I think the way to do this is to have the spine curve around inside the body so the shoulders and hips are where you want them. You can add ribs to the neck and tail sections to get the thickness to be even, and put the internal organs where it's convenient.

  • $\begingroup$ But how would the curved section work internally? And where would the ribs/organs go? $\endgroup$ Oct 11 '21 at 7:10
  • $\begingroup$ @IchthysKing The spine would have to do a 180 turn after the wings (probably with fused vertebrae), then another 180 turn where the hips are, so where the wings are there are three levels of spine going backwards, then forwards, then backwards again. The organs would be in the neck and tail and would be elongated like in a snake. There would be ribs in the neck (deviating from the standard tetrapod layout) and tail. There might be ribs under the wings, but not on the parallel sections of spine. Maybe the extra spine eventually becomes vestigial. It needs magic to fly. $\endgroup$ Oct 12 '21 at 0:38

It used to be a hexapod

Wyverns were once true dragons, six limbed, four legs and two magnificent wings extending from above the shoulders of their forelimbs, though through some manner of ill will or just plain bad luck one population of true dragons suffered a hereditary condition known as wyvernism that caused them to hatch without hind legs. They did not allow this to put them down, dragons have their pride of course, but this has led to those with wyvernism to be rejected by true dragons and only found companionship with others with wyvernism, causing more dragons with wyvernism and eventually cemented the condition into a species that are now referred to in bestiaries as wyverns.


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