Alright, this is a follow-up to Making T-rex More Dangerous Part 1: Proportionate Arms and concerns one of the most important factors in making a creature dangerous to humans: durability.

Sure, humans can kill anything with the right weaponry, but rhinos, bears, crocodiles, and so on are still dangerous because they resist common human weaponry. Sure, an RPG would kill them, but most people don't have RPGs now do they? Thus, in order to be a real danger to humans, one of the best ways to do it is to be big and tough.

My problem is, I'm not sure what would be the best traits to put under 'durability.' A cockroach or rat's survivability would be nice, but would the traits responsible for said survivability work on a T-rex? Is it even feasible for a T-rex to evolve that?

Tougher, thicker hide with fat layers would be helpful, but I'm not sure that a T-rex, a large, strong creature can afford the increased food intake necessary to have a thicker fat layer. Plus, that fat layer would likely make my T-mon (Tyrannosaurus Monster) slow, and I'm not sure that decreased speed is worth it, since even though this question concerns medieval weaponry, like swords, bows, ballista and catapults, medieval weaponry is still pretty darn deadly!

So my question is, quite simply: How Can I Plausibly Increase a T-rex's Survivability Against (Or Resistance To) Medieval Weaponry?

I appreciate your input and feedback, thanks everyone! If you choose to VTC or close-vote, please give me an explanation so I can improve the question.

  • $\begingroup$ Increase the strength of its feathers? $\endgroup$ – PcMan Feb 12 at 22:59
  • $\begingroup$ immune to bird flu so when it(T-mon) got tripped over a carefully laid log and it dies(as planned), every animals that feast on it will carry the deadly virus and start the spreading... $\endgroup$ – user6760 Feb 13 at 2:56
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    $\begingroup$ You kewp doing these questions long enough and your T-Rex either becomes an RPG dragon or Metal Greymon. $\endgroup$ – The Square-Cube Law Feb 13 at 5:03
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    $\begingroup$ You really want to make t-rex more dangerous? Give if mammalian primate predator-class brain and learning ability. Especially if it's smart enough to read and apply Sun Tzu's "Art of War" , von Clausewitz's "on War" and Wade's "Small Unit Tactics". $\endgroup$ – PcMan Feb 15 at 16:02
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    $\begingroup$ @PcMan: perhaps T-rex could become military Machiavelli? In that case, no one can win against him, and he conquers the world...."Dinosaurs are the superior species! I AM YOUR KING, HUMANS!" $\endgroup$ – Alendyias Feb 15 at 18:34

You want a monster of a species that's tough to eradicate? Look at yourself in the mirror.

In both your previous question and in this one you seem to be looking at it wrong. If you want you monster rex to be a bigger threat, you ought to look at the approach they took in the 2 jurassic world movies (spoilers ahead).

In the first movie they made a hybrid called the Indominus rex, a creature which was powerful, decently bulky and, more importantly, smart. It was able to escape containment, ambush humans and overpower a T-rex, and yet, despite having longer arms, it was incapable of doing anything when the humans entered a building, because it was too big. It's size also made it a much bigger target, which is one critical problem with humans: being bigger means you're tougher to kill, but also that you're not as mobile, which means that if I have enough pointy sticks to throw at you, I can just lure you into a big hole I dug or into another place to further hinder how much you can move around and just throw sticks at you until you die. Better yet: I can use your own weight against you by making a trap that can sustain my weight, but not yours, so that it goes unnoticed until you're on top of it.

So what happened in the second movie? Despite all the wrong ideas about why one would want a dinosaur in the military when you have anti tank rifles and drones, they did think something right: making the indominus rex smaller. That way it can access places where humans would hide from it, it can be faster and more mobile, it's a smaller target and one of the most important of all: it needs less food, and that is important specifically because a bigger and better brain requires a lot more nutrients to maintain itself at full capacity than a brain like that of a normal T-rex, and if you have a big body, while it can be said you'll need less food in proportion to your size when compared to a smaller animal with a faster metabolic rate, you still need more food in absolute numbers, which means a bigger body takes more food to maintain it, meaning adding a more powerful brain would further increase this already large demand, and as we already know that even without a human brain the T-rex already needed a bunch of food.

So how did it go in the movie: they made a smaller indominus with some different abilities but a few important traits to mind:

  • it was smaller and faster, but still larger than a human and, not being as massive as a larger animal would, it could deal with some added weight from tougher skin.

  • it was pretty smart, and understood well enough concepts like luring in prey by pretending to be knocked out or dead.

  • It could afford to have the longer arms you wanted in your previous question, because in here the smaller size naturally meant less space for jaw muscles, and thus the ability to use your forelimbs to help with climbing, grasping and pinning down prey make them more than worth the cost.

The main problem with this animal in the movie was that it was naturally bound by the laws of movie antagonists, meaning it worked much less like an animal hunting and more like a cartoon villain, but it's effectiveness is not to be ignored.

Basically, to get the horrifying monsters you want, your T-rexes should reach their top size at the juvenile stage, in which they're already larger than a human and powerful enough to overpower one, but the fact that they're far from being as large and heavy as an adult would make them much more mobile, much like it's assumed to have actually happened in the past, in which juveniles were assumed to hunt weaker, but faster prey, as they were more well built towards speed, while the adults hunted the bulkier, slower prey that required more raw power to be taken down; a difference which allowed for less competition between the adults and juveniles.

enter image description here

(image taken from saurian wiki)

Another major difference is slight tougher skin and longer arms. Since our T-Rex is smaller than a normal adult would be and has less powerful Jaws, additional help with pinning down and attacking prey is a good way to go. Modifications to allow for a wrist that isn't eternally locked in a bird like position is also more than welcome here. They'd still be smaller than the legs and would require a heavier tail, but would be more helpful than in the case of a fully gown adult.

Finally, the brain: your monster t-rexes will need essentially mammalian level brains, ideally almost as good as ours. Why? Because they're designed to be able to survive against humans in the long term, and the only strategies so far that were truly successful were living in locations we can't possibly go and never leaving, appealing to other humans to help you escape extinction or outsmarting us, with the last one being the hardest to pull out. Furthermore, we'll have your monsters gain durability by being less antissocial. We're making them pack hunters, because the smaller size and bigger brain means both that they're now capable of getting together and making coordinated attacks, but also that now, since they need less food, they can afford to hunt together without having the whole group starving. Add in some traits like a tougher more leathery skin and some osteroderms and you got a beast.

Summing up:to make your monster T-Rexes we'll make it so:

1-they're smaller, meaning they're more quick on their feet, are better at both pursuing and escaping at high speeds and so they need a lot less food to survive, meaning they can afford to be more social and that the environment can sustain more of them at a certain period. While this technically makes them less capable of tanking attacks, it increases their chances of surviving, meaning they can endure more damage in the long run than a more well armored T-Rex that wasn't as able to run away, because your wounds can only heal if you're not dead.

2-they're smarter, because we're proof that intelligence is by far the best strategy, and if their strong bodies come packed with a brain almost as capable as ours, they'll already be much more dangerous on their own than a fully grown but dumber adult would be. They're smart enough to track you and to trick you into a trap and they're small enough to be able to follow you almost anywhere you try to go to hide from them. They can also use this intelligence to avoid larger groups of people and isolate them in more manageable groups. Intelligence is by far the best weapon to make them more capable of surviving and more dangerous foes. They should be at least intelligent enough to understand the concept of using tools, so that they can potentially use things like shields, which can temporarily boost their durability and be ditched should they need to run away.

3- they're pack animals, because now instead of one big slow monster that will stop being a threat once you kill it, you have 6-10 smaller, faster and smarter monsters which can access your buildings, and if you kill one you're still 5-9 dead monsters away from being truly safe. While the individuals aren't as tough, the pack as a whole is much stronger, plus you'll need to kill all of them to end the pack. A pack is also much more capable at making traps and cornering an isolated human, and since they're faster, the human will be out of their element, since their ability to walk long distances will be worthless when they're caught in an ambush. Remember that even today an isolated human with a rifle can still get killed by a pack of wolves if they're not careful.

4- they're only slight tougher than a normal juvenile, because too much armor would start to hinder their speed and mobility, and the fact that they're pack hunters already makes them pretty tough simply because unless you're in a group as big as or larger than them, you won't be able to focus on a single target without risking being attacked by another member of the pack, which means your chances of attacking effectively and surviving go down. If you have to choose a pack that's tougher and one that's more mobile to fight humans, go for a more mobile one.

5- they will Finally get more proportional arms, but more importantly, they'll get more articulated and dexterous hands. The fact that t-rexes managed to reach adulthood should by default mean they weren't exactly incompetent hunters while in their juvenile phase, but it doesn't hurt to have arms capable of grasping. After all, humans have them, and a good amount of all of our weapons, tools and overall technology require dexterous forelimbs to be used. They might not be able to throw a spear or fight as well with a sword, but they might still be able to grab a human, pull a horse by its lead and operate a modem shopping cart. Now, what does having longer arms capable of grasping have to do with defense? Well you can hold a shield, can't you? And so can a chimpanzee, so remember to try to make your dinos as smart as those if you can.

If your monster rexes indeed follow all of these, you'll get a group of extremely efficient, scary and durable predators, because your brains suddenly aren't as much of an advantage as they'd be with a mindless beast, your weapons become less effective because you have much more than one target to focus on (although they'll still cause a fair amount of damage should they hit), your enemy can use some of your weapons and defenses against you and despite being only a bit dumber than you, they're physically much more capable. You're built to walk long distances and use that to exhaust prey, but they're just as good as tracking, but they won't need a horse to run fast, or to outrun you while you dash to warm the rest of the village about the monsters in whose trap you've just fallen while out to hunt in the forest nearby.

It may sound counter intuitive, but 5 normal hunters with the strength of one and durability of one can be harder to kill and better at hunting than a single hunter with the strength of 5 and the durability of 4, especially if the one big hunter is dumber.

  • $\begingroup$ So, essentially, your answer says "Okay, so look at Indoraptor; we're going to take that and do it as the movie writers should have and make an actual beast." +1 for that, great work! $\endgroup$ – Alendyias Feb 13 at 5:38
  • $\begingroup$ @Alendyias in a way. Like it or not the indoraptor might be one of the best examples in modern media to what your monster T-rex should resemble if it's meant to survive facing human civilization in a clearly hostile way. Temper with some details, add in some behavioral traits and we can make it even more efficient at hunting humans down. $\endgroup$ – ProjectApex Feb 13 at 6:42

The best defense you could give a T REX against humans is a larger brain.

I've noted some of the following in another post but to reiterate. On Earth at least evolution has provided the vast majority of animals with one or more of the following defenses against predication.

  1. Be poisonous/taste bad (mostly applies to insects and small vertebrates).
  2. Be camouflaged/hard to detect (almost all animals do this to some extent).
  3. Be fast (try to out run your predators).
  4. Be tough (have a thick shell/skin/spines or other form of amour)
  5. Be large (grow too big to be threatened by local predators when adult) e.g. blue whales, elephants and sauropod dinosaurs.
  6. Be alert (have good senses to help you detect predators).
  7. Be part of a group (the slow guy gets eaten not you).

There could be more I haven't thought of but that would be 99% of the 'tools' available to all prey animals on the planet.

Your problem? None of them work against the top predator on the planet. Just ask any of the myriad of animals like the woolly mammoth or the passenger pigeon that have gone extinct since we showed up. And the vast majority of that occurred when humans only had stone age technology not the engineering and metallurgical skills of the middle ages Europe.

I won't go through the whole list but suffice to say T Rex was already (4) & (5) because the same pressures that drive prey will also drive predators and T Rex (assuming he was mostly a hunter) had to be big and tough to deal with the large prey animals that were his food as well as competitors. Making them bigger as a defense against humans won't work as they were already much bigger than us and were near what appears to have been the top end of the therapod size range already. (There were some therapod dinos bigger than T Rex but not many.) So Rex was close to what appears to have been the upper limit.

Making him tougher won't work either. Giving them the thick hides and bony plates of Ankylosaurs for example would add a large amount of weight and slow them down (a lot) especially as they only have two legs to distribute the extra weight over. Also there are certain areas you just can't amour, particularly the belly and and leg/joints. Ankylosaurs were toast if they were rolled over on their sides! Ironically the medieval knights who would be fighting your Rexs would agree with (and understand) completely.

You also can't grow armor hard enough to withstand forged weaponry designed to piece armor everywhere on the body. Late developed windlass crossbows etc could draw 4000 pounds of force and were equipped with amour piecing points! Armour piecing pole arms and axes etc also forge hardened. There will always be critical week spots. Not to mention traps and pitfalls etc.

Improving (6) won't help much because apparently T Rex already had excellent sight and an even better sense of smell.

Improving (7) might help (a little) because as far as we know they weren't pack animals but again there was probably a very good reason for that. A pack of adult T Rexs probably wouldn't be able to find enough food often enough to feed all its members, let alone a herd (which would probably starve to death in a fortnight).

As for cockroaches and mice etc vermin like that are 'tough' only because they have very high breeding rates and are opportunistic feeders (they have wide ranging diets). They think T Rex, like most dinosaurs had a high reproduction rate already but also like other dinosaurs there was a high attrition rate from hatching's up to juveniles. So that doesn't help much. If you gave them bird-like behaviors with adults rearing young you would increase the number of survivors but then something else has to give (like their size or clutch numbers) because the ecology couldn't and didn't sustain hordes of adult T Rex.

Which gives only one option I can think of that would help. A bigger brain. Make them smarter, not necessarily human smart but smart enough to plan hunts, be wary of large groups of humans/disadvantageous encounters and/or work in small adult groups as needed. It worked for us.

  • $\begingroup$ Yes, a bigger brain is among those things they'll need; however, I feel (considering the size of a 'rex) that they'll need better protection so they aren't easily killed by spears and arrows. $\endgroup$ – Alendyias Feb 12 at 23:54
  • $\begingroup$ As noted above in al likelihood nature couldn't evolve armor tough enough to withstand medieval weaponry (at least the heavy stuff) nor could the animal carry enough of it to be practical. Some critical areas have to be left unprotected or it couldn't walk let alone run, bend over or even eat because the neck would be too inflexible. And every gap is a target. $\endgroup$ – Mon Feb 13 at 0:24
  • $\begingroup$ I would disagree; the Indomitable Ironclad Beetle can withstand 150 Newtons, or being run over by a car on a gravel road, and all that's protecting it is chitin. Couldn't it have segmented chitin armor, with tough hide underneath perhaps? $\endgroup$ – Alendyias Feb 13 at 3:04
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    $\begingroup$ There's always a 'special case' in nature. Get me a beetle that's 12 meters long, 5 meters high and weights 12 metric tons or more and we'll see how well it does walking let alone surviving in a fight. $\endgroup$ – Mon Feb 13 at 4:46
  • $\begingroup$ Fair; the square-cube law would kill that poor bug. Still, surely there's something that can be done to improve a Rex's durability and thus survivability. $\endgroup$ – Alendyias Feb 13 at 5:31

TL;DR - Armor the parts of the torso that humans could reach; weaponize the tail and use it to prevent humans reaching its legs; avoid siege weapons


  1. we are talking about physical durability, not general survivability (in which case the "intelligence" answers would be better)

  2. the scope is limited to anatomical adaptations and biochemistry available to Earth vertebrates have (so no carbon nanotubes or titanium-alloy steel in the scales, or Alien-style super-acid blood...)

To protect against spears/pikes from below

Tyrannosaurus already had gastralia ("belly ribs") in its abdomen - these are dermal bones not directly connected to the spine. I would enlarge and flatten these to form armor, and expand them from the abdomen up into the chest (protecting heart and lungs). I would also thicken the dermis and 'brace' the armor with tendons and ligaments to absorb shock.

To protect against arrows

Add armored skin, which is at least feasible for the broader theropod group - Carnotaurus had osteoderms (bony scutes) in its skin which have been suggested to be protective when fighting other members of its species.

To protect the legs

Make the tail more flexible, and give it spikes, or expand the vertebrae near the end into a club. Then have it lash the tail around while fighting numerous, smaller creatures (such as humans) so no one can get within halberd-, axe-, or sword-reach of its hamstrings.

Large-scale attacks

You just have to avoid these. No armor even a T. rex-sized creature can carry would protect against really heavy weapons such as a trebuchet or large ballista. But these aren't all that mobile - it may not be intelligent enough to recognize what these are (though crows are sometimes said to recognize that humans are only dangerous when carrying guns, so it's not impossible) but just avoiding large constructions that weren't there yesterday should work.

It also needs to not be easily panicked - to avoid tactics like chasing bison and even mammoths off cliffs - but that seems plausible for a superpredator like this.

  • $\begingroup$ Great answer! Your assumptions were correct, though answers on general survivability are welcome as well. I especially like how you covered categories of medieval weaponry one by one and came up with one for each of them! $\endgroup$ – Alendyias Feb 14 at 2:50
  • $\begingroup$ I tried to write a book with bronze-age-tech people who had domesticated dinosaurs at one point, so I spent quite a bit of time thinking about how one would armor a dinosaur (artificial armor in that case) for battle against people with spears etc. ;) $\endgroup$ – cometaryorbit Feb 14 at 6:55
  • $\begingroup$ If t-rex does turn out to be a pack hunter that will seriously help it against humans, humans have a hard time fighting large pack animals pre-gunpowder. It is much harder to harry pack animals to death, you have to isolate them first. $\endgroup$ – John Feb 15 at 16:29

Solid state redox circulation. Their blood still moves nutrient feedstocks for biosynthesis, but they don't have internal respiration where blood exchanges oxygen for carbon dioxide. Instead a network of conductive wires (with "synapses" to shut off short circuits and otherwise control power usage) brings in energy to allow direct CO2 recycling at the cell. (Normally I would propose this for zombies, so technically these now qualify as zombie T-rexes by my categorization)

Decentralized, rapidly reparable nervous system. The T-rex already has a fairly well decentralized nervous system with strong reliance on local processing centers due simply to its size. But now we're going to replace the myelinated portions of axons with ... a network of conductive wires. Additionally they bifurcate at a "synapse" (but all synapses at a nerve junction controlled by a single reflexive signal) so that there is a backup ganglion ready to take over the instant the main ganglion is destroyed or its nerve damaged. Last but not least we're going to work out a way that a conductive neuron can record a code for its connections at both ends, and send each to the other, so that it can rapidly rewire to its original destination. And we'll provide rapid ways to oxidize the metal of the broken neurons and reform it in replacements.

Stronger bones. With all this metal about, we might as well weave some of those neurons into strong membranous bones to protect the brain and form an unbroken ribcage.

  • $\begingroup$ Interesting ideas; could this evolve, or would this require intelligent design? $\endgroup$ – Alendyias Feb 13 at 5:35
  • $\begingroup$ I seldom understand why things do or don't evolve. It seems like a system capable of evolving insulation would be capable of evolving a wire, but Terran biochemistry seems to be a bit uncreative. No coal-digesting bacteria, no beta-proteobacteria replicating by explosives, no carbon nanotubes in the human skeletal system. But is that an accident of our evolution (too little time before multicellularity evolved), or a general limit in how organisms explore the adaptive landscape? $\endgroup$ – Mike Serfas Feb 13 at 10:41
  • $\begingroup$ Good point; since the scaly-foot snail exists, it should be fair to say metallic nerves exist. $\endgroup$ – Alendyias Feb 13 at 18:29
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    $\begingroup$ By the way, why is the decentralized, rapidly repairable nervous system so useful? Avoiding paralysis? $\endgroup$ – Alendyias Feb 13 at 18:30
  • $\begingroup$ Yes. If you think of it as a deer in the headlights, what is the hunter going to do? Aim for the heart, or aim for the central nervous system! The less CNS to be destroyed, or the more decentralized it is, the more dakka it takes to take that beast down. $\endgroup$ – Mike Serfas Feb 13 at 18:34

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