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Humans have horizontal shoulders. We can do all kinds of stuff with them, but what would it be like if we had vertical shoulders like a quadrupedal animal, specifically, a cat? What movements could the arm make/not make, such as throwing and rotating the arm?

This is a cat's skeleton.

This is a human skeleton! One of our own.

Cats and humans have drastically different skeletons, but I'm focusing on the shoulders and possible lack of clavicle.

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    $\begingroup$ A dog's shoulders, for example, are placed different compared to a humans. Here are some pictures showing the comparison. worldwideboxer.com/graphics/skeleton-front.jpg cms-assets.tutsplus.com/uploads/users/108/posts/31371/image/… $\endgroup$ Feb 23, 2021 at 21:26
  • $\begingroup$ I didn't know that! :O $\endgroup$ Feb 23, 2021 at 21:45
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    $\begingroup$ There are major differences between the way the forelimbs are attached to the body in primates and in the Carnivora. The bones are just a part of it: muscles and tendons are different too. As primates, we can move our arms freely in all directions, whereas carnivorans have much more restricted freedom. As primates adapted for brachiation, our arms can support our body weight under the body, above the body or sideways from the body (hang by our arms from tree branches, pull ourselves from a side) whereas the joints of carnivorans are mostly able to bear loads with the limbs under the body. $\endgroup$
    – AlexP
    Feb 23, 2021 at 22:55
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    $\begingroup$ ... As primates, we can rotate our forearms along their axis about 270°: this allows us to grip and pull objects with our palms upwards, downwards, inwards or outwards; carnivorans basically can only rotate their forearms about 90°, their palms facing either down on inwards. Overall, the skeleton of us primates is much closer to our (para-)reptilian ancestors then the skeleton of carnivorans, which is highly specialized for their lifestyle. We are generalists, they are specialists. $\endgroup$
    – AlexP
    Feb 23, 2021 at 23:01
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    $\begingroup$ Does this answer your question? Would there be problems in a humanoid with non-simian shoulders? $\endgroup$
    – elemtilas
    Aug 12, 2021 at 20:55

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Depends on how much humanoid are the things for you

What is a humanoid for you specifically?

For me a baboon have a very humanoid look.

But even with that have a posture more adapted to the quadrupedalism and maybe more comparable with felines and canines.

This could deplete their tool manipulating abilities compared with other primates but not in a really significant way.

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