I'm sure you have questions, so here's the idea: I want to include T.rex in my world as a "boss" monster, but due to research on Quora on T.rex's ability to survive against modern weaponry (firearms) and spears, I have decided that T.rex needs a few upgrades.

This question concerns the first of my intended upgrades, proportional arms; (there will be others, intended to make T-rex more dangerous to humans, but this question concerns whether or not proportional arms would increase a T.rex's survivability). You see, T-rex has arms about the size of us humans, which look ridiculously tiny on its body because they're not proportional. Without proportional arms, T-rex has the following Cons:

  1. Decreased Attack Options-Rexes can only bite, ram, stomp and maybe kick something if they want to attack.

  2. Balance Issues-Literal balance issues. T.rex relies on its tail and both proper positioning and stance to keep its balance, so a single misstep can send it crashing down (the same goes for us, but as far as I know, we are much better at steadying ourselves and recovering our balance than a T-rex). In other words, T.rex has to be careful or end up laboring its way off the ground.

  3. Getting Up-Oddly enough, each of a rex's arms, which are about human size mind you, can lift 400 pounds! However, a rex's arms, due to their proportionately small size, can only be of limited aid to a downed rex.

  4. Decreased Speed-In general, quadrupeds are faster than bipeds, therefore logic dictates T.rex would be faster if it had four "legs," or rather, four limbs that it can stand on.

I intend to give T-rex proportional arms to take away these Cons and therefore make T-rex a more viable opponent. Therefore, my question is: Would Proportionate Arms Increase a T-rex's Survivability and Lethality?

Please note:

  1. By Lethality, I mean a T-rex's ability to win fights and take down prey. Survivability should be self-explanatory.
  2. On my research I heard that proportional arms would take up valuable anchoring space for the muscles responsible for T.rex's incredible bite force, therefore decreasing it; the best answer should account for this, either confirming or debunking this potential myth.

As always, I appreciate your input and feedback, thank you all so much! Finally, if you decide to downvote or VTC, please give me an explanation so I can improve the question.

  • $\begingroup$ @user535733, I just edited to clarify: proportional arms are not to make T-rex more dangerous to humans so much they are supposed to increase the survivability of a T-rex, as well as it's capacity to win fights and take down prey. $\endgroup$ – Alendyias Feb 11 at 22:41
  • $\begingroup$ Okay @user535733, then how do you explain the tales of people sacrificing maidens to dragons in medieval Europe? Pretty sure dragons weren't cooked and eaten for dinner, so it is possible (albeit difficult) to one-up humanity. Seriously, look at bears! Most firearms don't work on them, because even after being struck with a lethal blow they can still hold onto life long enough to take you with them! $\endgroup$ – Alendyias Feb 11 at 22:58
  • $\begingroup$ I think both of those are great patterns to answer your question! $\endgroup$ – user535733 Feb 11 at 23:01
  • $\begingroup$ Granted, @user535733I do see your point; we have killed and eaten almost everything, even bears. $\endgroup$ – Alendyias Feb 11 at 23:01
  • 1
    $\begingroup$ making t-rex arms bigger would not make the creature more capable. Unless you make the arms long enough and suitable armed(heh) to function as primary weapons. But hen you don't have a T-rex any more. $\endgroup$ – PcMan Feb 12 at 14:54

Proportionate arms: Tool usage

Proportionate arms would mean giving a t-rex more incentive to use them.

Assuming the t-rex starts to gain intelligence, proportionate arms would allow them to more easily use tools without losing balance.

Proportionate arms: Larger Weapons

On top of that, proportional arms combined with the sheer size and power of the t-rex would allow it to handle larger weapons than humans. Let's do a graphical comparison below.

The following, personally hand-drawn t-rex obviously looks great and very realistic. However, as good and life-like as it looks, how could those grubby little human arms support that weapon fitting for an apex predator? A few shots would probably make the t-rex lose balance.

enter image description here

Conversely, with proportionate arms and a more balanced, proportionate body, the t-rex could hold its ground and allow it to use big, bad weapons fitting of its status: enter image description here


Proportionate arms would incentivize a t-rex to use them. Combined with some intelligence and proper tool usage, a t-rex would conceivably become more lethal than originally. The ability to use tools would hopefully make up for the decreased bite strength.

Obviously, a t-rex may not be able to get its hands on advanced tech like miniguns (as implied in the previous section), but a proper ultra-zweihander or even a large stone club would make them into veritable dark souls bosses.

  • $\begingroup$ Hold up, isn't Dark Souls known for its extremely difficult bosses? $\endgroup$ – Alendyias Feb 12 at 18:48
  • $\begingroup$ @Alendyias yup, think t-rex equivalent of Sif, the great grey wolf xD $\endgroup$ – Enthus3d Feb 12 at 18:49
  • $\begingroup$ Gave dark souls as an example because all the bosses tend to be oversized and difficult to beat $\endgroup$ – Enthus3d Feb 12 at 18:50
  • 1
    $\begingroup$ Ah, now I see, thank you! I'm already planning to post other questions intended to make my T-mon (Tyrannosaurus Monster) more dangerous to humans. $\endgroup$ – Alendyias Feb 12 at 18:52
  • $\begingroup$ @Alendyias no problem, dark souls may be an interesting place to turn to, should you need inspiration on that front. They have many monstrous bosses that are verified human slayers :P $\endgroup$ – Enthus3d Feb 12 at 18:53

The arms aren't the issue. Size is.

As a adult? Humans per se would be too small to be an attractive prey species for a T Rex because the amount of nourishment gained from chasing/hunting them is not sufficient to warrant the effort. It's the same reason you don't see lions as a rule hunting small game like rabbit. All predators tend to specialize in game species that represent the best trade off between the effort and risk involved in hunting them and the energy gained by eating them. So using the African savanna as an example you have small cats like the caracal which hunts birds, rodents and other small mammals, cheetahs hunt small antelopes and lions focus on larger mammals like zebra and wildebeest.

During its young/juvenile phase? possibly yes they might hunt humans but all the evidence indicates that T Rex like other dinosaurs grew very rapidly so humans wouldn't be a preferred meal size for long.

All of the above is also based on the assumption of course that Rexy was purely an active hunter though. As far a I am aware there is still ongoing argument about how much of its nutrition was gained via scavenging/scaring smaller predators off their kills. Basically the more they scavenged the less they hunted.

As far as the arms go? It doesn't really matter one way or the other. Allosaurus was a highly successful genus of large active hunters with well developed forearms that used them capture and hold prey. T Rex did just as well without them. Also and given the size difference between humans and an adult T Rexs longer arms wouldn't really help much at all. They were 4 meters tall! Even with well developed arms like Allosaurus they would almost certainly tend (I think) to overbalance and fall if they tried to reach down and grab a human - the animals center of gravity would be wrong for this kind of motion, at least at speed (and I can't see anybody standing around waiting to be eaten).

You'd be better of picking one of the smaller therapods as a key threat to humans, one that hunted in packs say. (But not velociraptor - they weren't much bigger than turkeys (mass wise)).

  • $\begingroup$ Thank you for your perspective, I will have to account for balancing the modified T-rex. $\endgroup$ – Alendyias Feb 11 at 23:58
  • 1
    $\begingroup$ You can always look at one of the earlier Tyrannosaurs rather than T Rex. They were smaller. $\endgroup$ – Mon Feb 12 at 0:25
  • 2
    $\begingroup$ As an addendum, the raptors in the Jurassic Park films were known to be unrealistically large, but they're referred to in the film as Velociraptors because it's intuitively easier to say than Deinonychus, which far more closely resembles the depiction (3 - 4 meters long, slashing toe-claws and an intelligent pack-hunting therapod) If you just want a human-hunting dinosaur, drop into the early cretaceous and watch out for Deinonychus $\endgroup$ – Ruadhan Feb 12 at 8:08
  • $\begingroup$ That or Utahraptor or Stokesosaurus. $\endgroup$ – Mon Feb 12 at 8:23

You need arms even bigger than that.

A human spine is more or less vertical straight up and down. Human arms extend forward from the same vertical plane as the head. I can thus reach something quite far away, grab it, and bring it to my mouth, and I do.

The TRex however is canted forward. Its spine is a diagonal or possibly nearly horizontal. Even if proportioned like a human, the arms would barely reach to the head. Anything the TRex approaches will be biteable before it is grabbable.

If you want the TRex to grab something like this delectable Take5 candy I have here and bring it to the mouth, the arms must be quite long. They would probably drag on the ground or be held out laterally as though the TRex were trying to take flight. If it actually were it could flap them hopefully. These arms would also shift balance forward requiring a longer or heavier tail as a counterbalance.

Human proportioned arms would however give Trexes another attack besides biting, stomping and tail whupping: rassling.

  • $\begingroup$ Thank you for your perspective! I've seen Therizinosaurus and I believe it's a good frame of reference for modified T-rex arm length, what about you? $\endgroup$ – Alendyias Feb 11 at 23:57
  • $\begingroup$ @Alendyias honestly, I'm not sure if it's worth it. Another important factor important to survivability is overall cost: would such long arms increase its success as a predator enough to be worth the amount of nutrients and energy spent to maintain them? Like it or not, out of the different mutations T-Rex's ancestors went through, a large dinosaur with a powerful bite and with limbs proportionally smaller was the one to rule, and the arms clearly didn't make it harmless to its prey. $\endgroup$ – ProjectApex Feb 12 at 0:21
  • 2
    $\begingroup$ @ProjectApex - 'armless, surely? $\endgroup$ – Stilez Feb 12 at 10:34
  • $\begingroup$ +1 for "rassling" :) $\endgroup$ – bob Feb 12 at 16:35

Would Proportionate Arms Increase a T-rex's Survivability and Lethality? By Lethality, I mean a T-rex's ability to win fights and take down prey. Survivability should be self-explanatory.

Probably Not.

How do we know this? Simple: the Natural Selection which produced the T-Rex body plan already optimized for these goals, or at least a very similar one. And many other species of dinosaur have this same general design, so we know the T-Rex wasn't a fluke.

Of course, this doesn't apply if you're trying to guage survivability outside of Cretaceous-period Earth, or are prioritizing killing things above and beyond what's necessary for securing food/safety/breeding rights, but it's generally a good rule of thumb to assume that evolution does its job well.

  • $\begingroup$ Good point; the T-rex is optimized for biting things, and evolutionarily speaking it's well-designed for its environment and role in said environment. However, I'm trying to make a T-mon (Tyrannosaurus Monster) that can be dangerous to humans....sorry I edited that part out. $\endgroup$ – Alendyias Feb 12 at 20:59
  • 1
    $\begingroup$ Great first answer though! Definitely gave me some things to think about. $\endgroup$ – Alendyias Feb 12 at 20:59
  • $\begingroup$ @Alendyias Well in that case... I'd suggest reducing its size and aggression, and increasing its intelligence. So that humans can train it, make armor for it, and put archers on its back. $\endgroup$ – Travis Reed Feb 12 at 21:19
  • 1
    $\begingroup$ Ooh....packs of armored Deinonychus could be good..... $\endgroup$ – Alendyias Feb 12 at 21:20

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.