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In the media myth of King Kong, there exists a gorilla; 50 feet tall. The largest great apes ever to exist were Gigantopithecus Blacki which, stood up to 9.8 ft, and weighed up to 1,190 lb. While this is good, it is much shorter than the 50 foot goal we want to achieve. How tall (or heavy) can I make a great ape? Is the legendary 50 foot ape possible? What would the evolution of a massive ape look like?

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    $\begingroup$ I thought this question was going to go a different way... $\endgroup$ – workerjoe Aug 5 '18 at 2:26
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No, it is not possible. Not even remotely. At least not with Earth mammalian biology being what it is.

Bones can only get so big / strong. But hey, we had some pretty tall dinosaurs walking around, so why not a giant ape?

Well, it comes down to joints, blood circulation, and a bunch of other fun stuff like that. Basically, once you reach a certain size our basic biology just can't keep up anymore.

That thing would swing an arm, and snap its bones in half, as the muscle power required to move its limbs would be greater than the strength of its bones (for that muscle to bone mass ratio).

If we were devising a different creature, with multiple hearts, a different circulatory system, etc. it might work out, however.

Fun Fact: some of the earlier, massive dinosaurs are believed to have had 2 hearts in order to circulate the blood throughout their massive bodies.

If you look at the history of our world in fossils you will notice that even the dinosaurs got progressively smaller as we get closer to modern times. Same with the megafauna that dominated our planet a few hundred thousand years ago. The more complex our biology became, the smaller we evolved to be. This is not a coincidence. Even blue whales, whose weight is suspended by the oceans they live in suffer from diseases related to their size by the time they die.

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    $\begingroup$ You have my upvote. But it would be nice to have some numbers here. Just for comparison, Wikipedia quotes adult T-rex's as being about 12 ft tall at the hip (given their posture, this would be their height). When you think of the features they had to evolve to reach that size, a 50 ft. tall ape really becomes even less feasible by the moment. $\endgroup$ – Renan Jul 8 '16 at 17:07
  • $\begingroup$ Could you expand on "It might work out"? $\endgroup$ – TrEs-2b Jul 8 '16 at 17:08
  • $\begingroup$ Largest sauropod was about 4 meters at the hip. $\endgroup$ – Jiminion Jul 8 '16 at 17:13
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    $\begingroup$ @TrEs-2b - for example in Avatar it is briefly explained that the humanoids of that planet are taller, and much stronger than humans because of "naturally occurring carbon fiber" in their bones/tissue. This implies there is a natural process in their bodies to build that in their bodies as they grow. Imagine a human with bones/joints that strong! They would basically be Wolverine. Think along those lines. A creature with an alien biology which looks like King Kong, but is very different from an ape "under the hood". $\endgroup$ – AndreiROM Jul 8 '16 at 17:14
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    $\begingroup$ Realize that the mass of a critter goes up by the cube of its height. So a 50 foot gorilla would weigh about 1000 times more than a 5 foot gorilla. That's a lot of weight that would require different structures to move and carry it. $\endgroup$ – Jiminion Jul 8 '16 at 17:15
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I know this question is a few weeks old however I'm not fully satisfied with the answers given and I feel more information could be added. If we take the 25 foot figure as standing height, a 1.8m tall Gorilla scaled up to 7.62m (25 foot) should weigh around 12 tonnes. Kleiber's Law states that metabolic rate scale to the power of 3/4 to the creature's mass (M^(3/4)). Using the formula 70(M^0.75) you can work out that a 14 tonne mammal has a BMR of 80,000 Kcals/day. multiplying by a further 1.4 gives you a very accurate figure of the actual calorie intake for Humans and Elephants. Using this method gave me a figure of aproximately 110,000 kcals a day needed to sustain King Kong. For simplicity, that works out at between 480kg-650kg of bamboo shoots. In comparison to a regular Gorilla which eats 18-20kg of food per day.

Whilst biologically, it could be possible, Apes do not have a trend of growing very large. Even the G. Blacki size estimate is commonly scrutinised as being inaccurately scaled. Additionally, as has been mentioned, the ability to jump does not seem possible and running is also unlikely.

Note: Whilst the square-Cube law doesn't account for Allometric Scaling, by comparing a Shire Horse to various Elephants and various Elephants to each other, I found that on every occasion the actual weight was slightly lower than the predicated weight using the Square-Cube law. It should be noted that 14 tonne mammals have existed in the past. Whether Skull Island could support a population of these animals is another question. Perhaps kong lived in an unexplored rainforest.

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  • $\begingroup$ So his mouth scales with the square… could he eat enough, physically? $\endgroup$ – JDługosz Aug 25 '16 at 8:52
  • $\begingroup$ That's something that's never come up before. Considering sauropods were a lot more massive than Kong and relatively small heads, my initial reaction would be to say that it shouldn't be a major factor. Gorillas are known to eat grubs and insects and Skull island creatures tend to be larger and more carnivorous. 130,000 kcal roughly equals 45kg-90kg of meat or 100kg of crickets (aprox. 190 Weta-rexs seen in the film). An elephant spends 16 hours a day eating and is purely vegtarian so I think this checks out. Also consider that Skull Island flora may be much denser in nutrients/energy. $\endgroup$ – Zac Walton Aug 25 '16 at 20:07
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This video sets out the basic problems with a 25 foot tall King Kong. This suggests a fifty foot tall King Kong will have even more obstacles. On the plus side, the video is amusing, informative, and mercifully brief. Of course, YMMV.

A 25 foot tall Gorilla would weigh 60 tons and while his skeletal structure, his bones, and circulatory system could support this, his ability to move around would be severely limited. Let alone his ability to fight or jump around. Also, being a herbivore Kong would be spending most of his time simply eating plants. In fact, if he was eating the same proportion of his body weight that a normal gorilla does, this is one-eighth of its body weight per day, Kong would be eating 7.5 tons per day. It is easy to suspect Skull Island would have been stripped bare of its plant resources

Because Kong is an island dweller, and because the ecology of the habitat affects the size of animals this will influence his size, in fact, the smaller habitat the smaller the animal. The dinosaurs, for example, which were huge, lived on very large continents. The remains of Pigmy Mammoths were on the islands where they had lived. So if Kong is giant gorilla and an island dweller, he must be a pigmy giant gorilla.

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  • $\begingroup$ This is borderline not an answer because of how heavily it relies on an external, linked resource (and Youtube videos have a habit of disappearing, or being available or unavailable in different parts of the world). IMO it meets the bar for being an answer, but only barely. Can you incorporate some of the salient points from the video, to make this answer stand more on its own? $\endgroup$ – a CVn Aug 23 '16 at 7:54
  • $\begingroup$ @MichaelKjörling The incorporation has been done. Hope the changes meet your approval. $\endgroup$ – a4android Aug 23 '16 at 12:34
  • $\begingroup$ Looks much better now, though I haven't compared to the video. $\endgroup$ – a CVn Aug 23 '16 at 12:56
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    $\begingroup$ @MichaelKjörling. Paragrahh 2 is information straight from the video (although a calculation was necessary). The next paragraph on size and ecology is an added extra. $\endgroup$ – a4android Aug 23 '16 at 13:43
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50 feet - probably not. Scaling from a 6 foot, 400 lb gorilla by the square cube law, the 50 foot gorilla will be 8.33 times taller and thus:

$8.33^3 = 578$ times heavier

$578*400 = 231204$ lb or ~116 tons

That is at or beyond the largest sauropod dinosaurs - a recent estimate published in PLOS One (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3864407/) suggests 83 metric tons (= about 91 US tons) for Argentinosaurus, which is often considered the largest (in terms of mass) dinosaur. (The introduction to that paper also has some very relevant general information and cites about biomechanics at very large sizes.)

However... the sauropod dinosaurs had pillar-like legs, unlike Kong, and also had a suite of helpful adaptations no mammal has (heavily pneumatized and thus lightened skeleton, egg-laying and reproductive maturity far below maximum size which avoids the problem of very low reproductive rates faced by huge mammals, non-chewing-intensive feeding style).

But the smaller end of Kong portrayals - say ~20 feet and ~7 tons - is well in the mammal range.

And while elephants have pillar-like legs, Tyrannosaurus was a biped with much more 'athletic' leg type in the ~8 ton size range.

With the right evolutionary pressures, I'd expect apes to at least be able to reach the 2-3 ton range many mammal groups have broken into, including some very improbable ones (glyptodonts - basically giant armadillos - were >2 tons at max, and Megatherium, a sloth, was 4-5 tons!). The therizinosaurs were also 'grasping' browsers in this kind of size range, up to 5 tons.

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By our genes we are supposed to grow as much as 2.28 meters(7'4 feet) if met good environmental conditions like:

  • Balanced diet
  • Lack of environmental stress
  • More oxygen

So by our genes we are all supposed to be 25-30% bigger. Given some particular diseases you can surpass the genetic limit by 2%-3% at the cost of 3/4 of your lifespan.

So a human 33%-35% taller than the average will live less than 25 years, but would still be bigger.

I believe you could use the same disease on similar animals.
Indricotherium as example was 8 meters tall (26 feet) and 30 weighted tons. With this disease it could grow up to 12.8 meters (41'9 feet)

That's quite close right?

So terrain mammals can technically get close to 50 feet tall....

However shape also matters, and a giant gorilla doesn't have the shape of Indricotherium.

Given this giant gorilla also grows bigger muscles and bones and a bigger heart to survive long enough to reach it's maximum size then it could probably grow just 6-7 meters tall... maybe maybe even up to 8 meters (26'2 feet) if this animal was breed perfectly for a bigger size.

Those conditions to reach 8 meters instead of the 6 meters theoretical limit would be:

  • Half the earth gravity
  • Lifespan longer than human,the life of a primate won't be enough to grow this much.
  • Eat 30% of it's weight daily, mostly fat.

Fat is hard to obtain from herbivore diets and becoming carnivore is impossible for such a big animal as carnivores have to be small and fast....

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  • $\begingroup$ I'd argue the T-rex proves your last point wrong, but still, Great answer! $\endgroup$ – TrEs-2b Jul 8 '16 at 17:38
  • $\begingroup$ my bad , I meant ''carnivores have to be smaller than their prey''... an exceptions would be omnivore predators $\endgroup$ – άλεξ μιζέρια Jul 8 '16 at 17:39
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    $\begingroup$ Carnivores most definitely do not have to be smaller than their prey. Just taking the T-Rex for example is enough to prove the point, as the T-Rex didn't ONLY hunt sauropods. It also hunted things that were smaller than it. Another example is cats hunting birds and mice. Cats are significantly larger than both. $\endgroup$ – Aify Jul 9 '16 at 0:55

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