In the story I'm writing, a group of African penguins evolved to be fully upright (instead of having their knees bent like modern penguins).

enter image description here

Now some basic characteristics of these "erect penguins" are:

  • 7 feet tall erect bipeds
  • Pack hunters (still carnivorous)
  • Socially monogamous
  • More slender than modern penguins, lacking any blubber
  • Powerful legs
  • Powerful beaks (used to peck their prey to death)
  • Top running speed of 30 mph
  • Flippers that are used for balance when running
  • Proportionally longer legs than body
  • Slightly thinner and longer neck

Given these characteristics, could such a creature exist, and what evolutionary pressures would lead to them?

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    $\begingroup$ Also no blubber, if they're outside the polar regions. $\endgroup$
    – Spencer
    Commented Mar 25, 2020 at 23:26
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    $\begingroup$ Upright position - brings the problem of body balance while running at 40mph = 64km/h = 17m/s. Kangaroos - upright - are reaching these king of speed, but are mostly hopping. $\endgroup$ Commented Mar 25, 2020 at 23:47
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    $\begingroup$ "steering" in this case means to help with balance when running similar to ostriches $\endgroup$
    – icewar1908
    Commented Mar 26, 2020 at 0:00
  • 2
    $\begingroup$ In short, they evolved to run. That is the pressure. I'll see if I can elaborate on it later in an answer. $\endgroup$ Commented Mar 26, 2020 at 3:15
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    $\begingroup$ Then basically what you want is for your penguins to evolve into more upward standing, slightly smaller version of Titanis. I mostly agree with plutian, except that I'd find it easier for their hip bones to grow like we saw with terrorbirs and ostriches than for the tail to grow in length. $\endgroup$ Commented Apr 5, 2020 at 18:56

2 Answers 2


The reason penguins have their knees above their hips is purely for balance. The kneeling pose means the center of mass is always below the pivot point, giving much added balance, which is needed for slippery surfaces.

When further evolving this away from the polar regions, then a fair few characteristics would change to adapt and increase survivability in the new region. This is of course given that the species survives long enough in the new area to evolve this way, as a slow fat penguin makes for a tasty snack for the African predators.

The added balance is not needed, and speed is favoured to run away from predators. This means the legs will extend, and the knees will indeed be below the hip. This will come with added height, so a longer neck is needed to reach the ground for feeding. With this, a horizontal body rather than a vertical one is preferable as they would near constantly be bending over. This means the upright state of them is questionable.

As for balancing while running, I would rather expect a larger tail rather than the flippers, as the wings are mostly tucked away in most bird species for added aerodynamics. With this, fluffier feathers will be needed to create drag, as a fully aerodynamic bipedal body won't balance very well at high speed. This is less manoeuvrable in water, so I would expect them to swim less or not at all.

Basically what I have just described as an evolutionary prediction, is (as the comments pointed out) an ostrich. You could play with how they look a bit, but it would be best to take them as a base and merge them with the penguin characteristics you would like to retain.

Of course, if you want this to be a sentient species, the dynamic would change. The human-like upright body would not be out of the question, but they would need appendages for tool use. As it is commonly believed tool use was the catalyst for humans to start developing sentience, they would need the appendages for that. Also they would need a larger head to accommodate the larger brain capacity.

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    $\begingroup$ not just balance but also the hip anatomy, birds don't have the same hip joint mobility mammals do, the hip joint and musculature is drastically different. To rotate the legs that far, you also need to rotate the pelvis otherwise you have no muscles to to attach to the back of he leg. $\endgroup$
    – John
    Commented Mar 26, 2020 at 12:24
  • $\begingroup$ @John come to think of it would they even have bird like legs or would they have more humanoid ones? $\endgroup$
    – icewar1908
    Commented Mar 27, 2020 at 21:12
  • $\begingroup$ legs maybe but human like hips would require a drastic redesign of the avian hip, and if therizinosaur are any indication evolution will twist the hip at a right angle before that happens. $\endgroup$
    – John
    Commented Mar 28, 2020 at 2:52
  • $\begingroup$ @John so bird legs got it $\endgroup$
    – icewar1908
    Commented Mar 28, 2020 at 16:55

Umm ... Frame Challenge

Basically you have just described ostriches. By the time they have done all this evolving, they won't look anything like penguins anymore. They will in fact look like this.

enter image description here https://images.wordseye.com/ws-image-db/2016-6-2/51315.jpg


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