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I have a (digitigrade) quadrupedal alien creature with one of it's front limbs having a longer metatarsals, I'm trying to visualise how it would walk with this deformity for an animation.

I'm having trouble with how the leg would act as the right, regular leg lifts up and moves forward since the deformed leg now has to carry the front half alone for the right to complete its step, this involves left leg straightening underneath the body so it can then also step forward again.

The basic wireframe looks like this: three frames, natural stance is the final frame (stair shaped)

A more detailed sketch of the front legs: enter image description here

This is a painless birth defect called 'Stiltlimb' and not natural to the species; a gmo made for the purpose of a service animal, that being said the species itself is very prone to defects and the like, a struggle for the company trying to sell this new branch of science.

If anyone with can make sense of my scrounged up jargon and the scribbly drawing, I'd love some help!

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  • $\begingroup$ Trying to work out how this creature might evolve and thinking of the aye-aye. Can you tell us more about why it needs a long finger to stand on - give us some context to understand if you would. $\endgroup$ – 011358 smell Sep 4 at 18:31
  • $\begingroup$ Having larger metacarpals on one foot isn't going to affect stride, it just makes a larger foot, doesn't it? Also, the term metatarsal is more accurate, if this limb is only for walking. $\endgroup$ – Halfthawed Sep 4 at 18:36
  • $\begingroup$ It being digitigrade makes it so it stands on it's phalanges (toes / fingers) and not the metatarsal so it does alter the stride a bit having them longer than the other limbs. If it walked plantigrade then it wouldn't be much of a problem. Thank you for the wording tip! $\endgroup$ – Corvid Sep 4 at 18:47
  • $\begingroup$ @Corvid you need to use the <@username> format to ping someone (without the <>), at the moment no-one knows which comment you're replying to. $\endgroup$ – 011358 smell Sep 4 at 18:51
  • $\begingroup$ Could you please edit your question to reflect recent comments. Also could you clarify the ambiguity, that you don't want it to walk that way for "writing, reference,curiosity....". You would need to give us worldbuilding context to answer the question - else you are asking us to give context to something undefined. At the moment, I'm voting to put on hold as unclear what you are asking, this could be remedied - simply edit the question to fit with our conditions. When you have a moment, you can take the tour and read up in our help center about how we work. Welcome to the site. $\endgroup$ – 011358 smell Sep 4 at 19:08
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You actually have a lot of resources for visualising how odd-limbed creatures move in the 'real world'. A great example is this cuddly chap.

enter image description here

spoilers

In Stranger Things Season 3, the Mind Flayer takes on a freaky embodiment of meshed animal and human corpses. Whilst technically not four-legged, it is an excellent example of four-legged lame movement being fast, agile and dangerous (see the video link I posted up-top). Obviously if you have Netflix, go support the show and give it a watch. It's worth it regardless.

I don't know how well versed you are in animation, but you should definitely play around with skeleton rigs in Autodesk Maya. You seem pretty good already, but there's nothing like a little experimentation.

Other examples of fully-formed rigs with limp-like movement may also be useful to you. Creatures like the Ing from Metroid Prime 2 show that this can be done in an impressively realistic yet subtle way.

In any case, movement should by rhythmatic (not a constant march, more like a dance if that makes sense) and the shoulder of the affected leg shouldn't drop below the opposing shoulder at any point in movement. Hope this helps- your project looks amazing by the way.

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As a birth defect, it would have a measured limp and the uneven gait+weight distribution would make it useless as a labor animal, not to mention leading to spinal problems later in life. I lost the cartilage in my right knee in the Marines, and the small difference in weight distribution has led contributed to posture and lower back problems over the 20 years I have had the issue.

For visualizing how it would walk, I suggest using a free 3d modeling program (like Blender) to make a quick mock-up of the creature and try to rig it for walking animation.

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    $\begingroup$ Yeah that sounds about right! thanks also for the added insight of later life problems it would encounter, that is very helpful. The Blender idea is very good, I didn't think of that since I put my 3d projects on hold! That knee issue sounds terrible, sorry to hear but I appreciate you sharing that. Oh and yes, specimens like those are usually euthanised. $\endgroup$ – Corvid Sep 5 at 8:53
  • $\begingroup$ Eh, it sucked for the first 5-10 years. After a while, it's just how you are and you go on with your day. But thanks for the concern. My intent was not to garner sympathy, but to illustrate just how profound a difference even a small skeletal imbalance can have. Another example is horses (and other hooved animals). Most that are born with slight differences in leg length have to be put down or go through a lifetime of extensive surgeries just to be able to remain mobile enough to eat and have normal organ function. $\endgroup$ – HA Harvey Sep 5 at 9:45
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Orthotic lift shoe.

These are not wild animals. They are service animals. They can get help from their owners. Their short leg can wear a lift shoe.

source

lift shoe

You can get custom lift shoes. Depicted is the Even Up, a cheap temporary lift shoe. In the picture, the woman has a walking cast which makes her right leg longer. The lift shoe increases the thickness of her sole on the left side, so it is a match and her gait is even. Lift shoes are helpful for polio survivors or other people with a limb length discrepancy, congenital or acquired.

Your animal can wear a prosthetic on the short side. That is nice too because I assume the long side is long for some reason (manipulating things?) and it is unencumbered by any shoe.

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  • $\begingroup$ I really like the idea of a prosthetic or specialised shoe, thank you! Stiltlimb isn't natural for the species so gives a lot of difficulty for the individual born with it. $\endgroup$ – Corvid Sep 6 at 14:40
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It's possible they could have sort of a second knee, allowing that limb to be "folded up" and still useful... how will they be using this limb and is it common for that species?

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  • $\begingroup$ It is a birth defect / mutation that is fairly common for the species, there are a lot of unwanted abnormalities as they're not 100% naturally occurring, gmos. $\endgroup$ – Corvid Sep 4 at 18:41

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