The carnivore/omnivore/herbivore army from this question about herbivores has reached the battlefield and the opposing army is a collection of large, scaly, occasionally feathered animals that no one has seen before. Dinosaurs!

Each army has an equal number of carnivores and herbivores in each weight range, so a comparable number of fox sized predators, a comparable number of lion sized predators and so on. On both sides, smaller combatants are more numerous than larger combatants. However, the dinosaurs have a collection of super-heavy carnivores/herbivores that the mammals have no equivalent to. Examples of the super-heavies are the tyrannosaurus-rex at 18,000lbs/8164kgs and the triceratops at 28,000lbs/12,700kgs. The mammal's "super-heavies" are the grizzly at a pitiful 1400lbs/635kgs and the African bull elephant at 15,000lbs/7,000 kg. The only consolation to the mammals is the dinosaurs only have a handful of their super-heavies to field.

The dinosaurs have the same uplift as the mammals (ie, human intelligence but no tool usage and vocal communication regardless of actual physiology). The dinosaur army is composed of dinosaurs strictly from the Cretaceous period. A helpful list can be found here.

Handling the logistics of how to feed so many carnivores and herbivores are out of scope of this question. (Yes, wars are won on logistics but that's a different question). Also, why these two armies are fighting is out of scope.

As the mammal's commander in chief, how would the mammals counter the super-heavies fielded by the dinosaurs?

This is question so links to official sources are recommended but not required.

  • $\begingroup$ It's worth noting that mammals became the dominant species on Earth only after the dinosaurs were removed from the picture. $\endgroup$ – Frostfyre Sep 16 '15 at 15:46
  • $\begingroup$ Are extinct mammal species allowed to join the mammalian army? If you can bring in long dead dating to more than 65 million years, I guess there is little harm in bringing in some recently extinct mammal species (20 - 30 million years ago). No? $\endgroup$ – Youstay Igo Sep 16 '15 at 16:43
  • $\begingroup$ @YoustayIgo let's just go with living mammals. $\endgroup$ – Green Sep 16 '15 at 17:51
  • $\begingroup$ Send in a zillion shrews to chew up the dinos. $\endgroup$ – Oldcat Sep 16 '15 at 18:48
  • $\begingroup$ Bats are allowed? They are mammals. $\endgroup$ – Youstay Igo Sep 17 '15 at 6:27

Most of the super-heavies could be hindered by pot holes, very uneven ground. One of the most dangerous things for a brachiosaurus is a broken leg. It is pretty much done at that point. These animals can't really jump and pits would either get them caught or possibly break important bones.

Having only two legs the Tyrannosaurus might be a bit harder to catch in such a trap but should they be caught they will be just as disabled should they fall in or break a leg.

This also leads to the tactics for attacking them. large mammals going for the legs and joints of the ultra large. breaking a leg will take them out of the fight. (would be a similar problem should an elephant break a leg...

Of course mammals fighting Dinosaurs might have a bit of an edge should they commence the battle in a winter wonderland...

  • $\begingroup$ It's been theorized that dinosaurs like T-rex could continue to walk on a broken leg. I can't find any links at the moment (everything points to modern healing medicine using dinosaur bones), but using traps may do little more than slow them down slightly as a result. $\endgroup$ – Frostfyre Sep 16 '15 at 16:04
  • $\begingroup$ @Frostfyre I haven't seen that anywhere yet. then maybe they'd have to break both legs... $\endgroup$ – bowlturner Sep 16 '15 at 16:06
  • $\begingroup$ @Frostfyre - they certainly have found Rex skeleton with signs of considerable damage, and healed and partially healed damage. So those fellows could take a lickin' and keep on tickin. $\endgroup$ – Oldcat Sep 16 '15 at 18:46
  • $\begingroup$ I thought that the mammal commander could order a bunch of moles to put tunnels and mole Hills on the dinosaur's side of the field. There's your traps. $\endgroup$ – Green Sep 16 '15 at 20:58
  • $\begingroup$ Couldn't they just go around the pits? This also seems to assume that there are no small dinosaurs. I'd imagine that successfully breaking the legs of a T. Rex surrounded by raptors would be significantly more difficult. $\endgroup$ – ckersch Feb 26 '16 at 21:01

Why exactly are we limiting mammals to currently existing species? The mammoth could weigh as much as 12 tons, the Indricotherium was even larger than most dinosaurs! The greatest of mammals could certainly hold their own.

That said, limiting it to current animals -- why not swarm the larger enemies? Cooperative hunting is one of the hallmarks of mammals.

Mammals are also well known for killing far beyond their weight class -- we have weasels that kill rabbits ten times their sizecougars that kill animals more than four times their weight and polar bears killing whales!

It's honestly a wild guess how mammals would fair against dinosaurs -- but don't count them as down and out.

  • $\begingroup$ Hey Axelrod, welcome to Worldbuilding. The question you have right now aren't really an answer to the question, rather it's commentary on it. Would you care to change your answer to be less commentary? $\endgroup$ – Green Sep 17 '15 at 1:39
  • $\begingroup$ I've upvoted you as a welcome gesture :). Green is right. You should focus on how the mammals can bring the heavyweight monsters down to their knees, instead of explaining what the mammals can do. $\endgroup$ – Youstay Igo Sep 17 '15 at 13:27
  • $\begingroup$ Hey Axelrod, I'm voting like crazy and you got lucky ;-) $\endgroup$ – Rand al'Thor Dec 18 '15 at 1:45

In a fair-ish fight, I doubt they'd stand a chance: sure, they be more mobile, but it's about angular velocity: if you have to outmaneuver me by running around me, you have to move much much faster than I need to just to spin around on myself.

So what is the right way to approach this problem? You can use their sizes against them to prevent the fight completely. We can summarize by "use the terrain", but for a few example:

  • Fight in a narrow space, such as a series of caves/tunnels where they have no way to enter the battle. Use choke-points (Thermophiles, anyone?)

  • Use bridges: if you manage to re-route your troops over non-massive bridges, there is no way those would be able to stand a T-rex (think of one of those stereotypical movies bridges set in the mountains such as Tibet: a bear can cross it, a T-rex won't. Note that this may exclude your elephants and similar-size animals too).

  • Use crumbly/hard to maneuver on terrains: fight on the steep side of a mountain, or somewhere very prone to landslide or sinking (snow, crumbly rocks, mud, etc.). This may even score you some extra kill as the T-rex falls on his comrades.

  • Fight in water: Assuming that the dinosaurs don't have water-based super heavies (in your example you only mentioned land-based ones), fighting in (deep) water prevents them from accessing the battle

  • Use air attacks: If you can manage to drop some massive nets from the air on them, this will likely make them fall and immobilize them

  • Hinder their mobility even more: use some fast land runners as the balls on a bola (with a very sturdy chain), think two cheetahs holding a rope in their mouth and tying up the legs of the T-rex. How is he going to get free with his short arms (and no assistance from his comrades)?

Another very valid option is that of psychological warfare:

  • Bribe them: straight on, try to make them switch sides. Even having a single one turn sides may be a massive hit to morale, and in turn make the whole other army suspicious of the traitor's species, hindering the battle collaboration/trust.

  • Have some of your more "dino-looking" animals (Komodo's dragons? Crocodiles?) infiltrate the enemy and spread rumors with the same intent of the previous point, even false-flag some terrorism event in the ranks if needed.

Finally, consider using "artillery-like" weapons. If you can lure the big ones in certain spots, given their size, they'll be easy targets for things like a provoked avalanche.

  • $\begingroup$ I just realized that the question was about Mammals. Unless you can find a dino-looking enough mammal (or can dress up one well enough), scratch the second psy-ops suggestion, even though you can still carry on some false flag ops! You'll just have to do that from the outside. $\endgroup$ – Diego Martinoia Sep 16 '15 at 15:45
  • $\begingroup$ +1 for the bribe idea. As Green granted them a human-like intelligence, let's exploit that! $\endgroup$ – Madlozoz Feb 26 '16 at 19:29

I depends widely on the battle ground. My general feeling is that mammals are more versatile.

Savanna/ plains

Other contributor seems to see this as the default scenario.
I'd say that a brachisorus with a human brain and agressivity is almost imposible to stop. Especially flanked with 2 T-rex and a protected by few bird to intercept eye-targetting bats.

dominance factor: 68.5%


As annalysed above, I don't think mammal stand a chance. So I take a bunch of naked mole-rats and stay underground until they get tired

Shame factor: 0%

Forest/urban environment

Mammals can ensure a draw game. There is no way the dinnos will get my orangutan squad if I don't send them to combat.
By throwing stones (or standard fight if dino are crazy enough to get in the trees), Orang would wipe out any medium sized dino.
A big stone from a giant sequoilla would kill anything, but the dino commander would not fall in the trap.

Giant dino would have mobility problems. African forest elephant and their tusk could take advantage of this.

dominance factor: 62.2%


EDIT: More search needed


Biggest animal would be nothing but sitting duck, here.

Some raptor-like dino could give a fight, but I can't see them win agains a mix of bear, Jaguar, or mountain goat

Above all, on very steep ground, 10 Homo-Sapiens with spears would genocide any herd of anything.

dominance factor: 72.2% (four legged mammal only)
92% (If humans are allowed)

Open air

A tricky one.
Birds are dinosaurs. And I am sure that no bats could outfight a modern bird.
But cretacean birds?

I just can't find example of big cretacean birds. And it seems that, compared to modern birds, they where poor flyers.

Yet, the body of small birds is something rather bulky. I am sure that many primitive birds could reach a 60km/h speed. 2 or 3 of such bird ramming a Pteropus vampyrus would bring him down. Bird may even survive the collision.

dominance factor: 84.0%

Open ocean

I summon 1 sea cow. As there has never been any fully aquatic dinosaur, I win!

Spinosaurus can swim, but 3 orcas would tear him apart in minute.

MAMMAL WIN dominance factor: 100%


sand dessert

rivers and lakes

small tropical island


  • 2
    $\begingroup$ Understanding on arctic dinos is likely incorrect. We like the warm blooded vs cold blooded....dinos were neither. Assumption they cant survive in arctic is based on assuming they are cold blooded only $\endgroup$ – Twelfth Mar 22 '16 at 21:32
  • $\begingroup$ Actually, I am aware of this(at least of the lack of certainty). I based my wrong conclusion of an article I read long ago describing only raptor sized-dino. Actually, there was big theraupodes such as Cryolophosaurus. I will change this when I have time $\endgroup$ – Madlozoz Mar 24 '16 at 8:14
  • $\begingroup$ Note the science-based tag. Is there any references you can cite or any explanations you can give for the claims made in this answer, including the percentages given? Just for a start, I have no idea what a "dominance factor" would be in this context, let alone how you'd calculate it to three significant digits percentages. While the science-based tag doesn't outright require scientific citations, it is always a good thing to aim to at least explain any non-obvious claims made in an answer. $\endgroup$ – a CVn Mar 24 '16 at 9:40

One of the hardest things to counter would be large carnosaurs hunting in packs. While we are used to seeing T-rex as a lone hunter in movies and SF TV shows, there is some opinion that they hunted in family packs (young T-Rex chicks would stay in the nest, but older ones were gangly teenagers with proportionally longer legs, and may have been used to chase down prey to the waiting adults hiding in a copse of trees. Being hungry teenagers, the young T-Rex acting as "beaters" would have a great deal of incentive to take part in a cooperative hunt...).

The best way to counter that would be to incentives the carnosaurs to turn on their own kind. The mammals would have to hide out and use scorched earth tactics to ensure the carnosaurs become very hungry. And just behind the advancing carnosaurs is an entire enticing array of steak on the hoof, steaks they were evolved to eat in the first place...

  • $\begingroup$ Question mention that dino have human-level inteligence (that definitly make them VERY dangerous) and food logistic is not a factor. I guess the fight promoter will para-drop crates of food $\endgroup$ – Madlozoz Feb 26 '16 at 19:16
  • 1
    $\begingroup$ Human level intelligence or not, removing their food supply will make them start looking for another meal. And being smart, they know just what the best food for carnosaurs is..... $\endgroup$ – Thucydides Feb 27 '16 at 5:34

If bats are allowed then all you need is a group of large bats (and flying squirrels/foxes?) flying around their ... eyes, fluttering their large wings, occasionally poking them.

Some monkeys/gorillas armed with pointed stones, climbing on them (jumping from backs of elephants/necks of giraffe to things like T-Rex and spinosaurus) could actually kill them by simply prodding them heavily along the vertebral column over and over again until the vertebrae are deeply damaged and ... (the details are too gory so I'd avoid mentioning them. It would be one of the most brutal and horrific, slow, disabled death).

Also you could deploy Punji Sticks with venom coated tips in tall grass. Your troops must not enter that grass field and lets the enemy ...

What else do you want?

  • $\begingroup$ You forget that birds also count as dinosaurs. Even primitive birds would probably be dominant in the air (BTW flying foxes are bats) $\endgroup$ – Madlozoz Feb 26 '16 at 19:13
  • $\begingroup$ If you talk THAT way, then mammals are also reptiles (synapsids) and you can relate them to dinosaurs. $\endgroup$ – Youstay Igo Feb 27 '16 at 12:26

Assumptions to challenge.

A) dinos do not forn a regular army...disorganized irregulars at best. Good chance theyll not cooperate readily.

B) dinos giant size is directly related to the atmosphere involved. The atmosphere was heavily oxygenated and they were pushed to their extreme size because of this. These dinos would be significantly smaller in our atmosphere, or reversely, mammals would likely be significanlty larger in theirs. Creatures like the woooly mammoth could be 10x the size when put into the dinosaurs world.

C) humanity is directly responsible for the extinction of the largest mammals on the globe. Cave bears for example were significantly larger than grizzlys, but we killed them all. The short faced bear fell to extinction as well...this north american beast was 900kg and stood around 12 feet tall. If you include extinct mammals, you will see larger sizes on the mammal side.

This gives me the impression that given the right set of conditions that gave rose to the dinosaurs would give rise to larger mammalian creatures as well and the mammals would infact have their giants.

Also need to define dinosaurs...there was a 3 foot long dragon fly species that would tear apart most mammals their size and could also include swarm tactics. Is that a dino? They were alive then...

Lets get rid of the assumptions and give the impossiblity that these creatures could exist together in these states...it really comes down to tactics of a semi 'regular' mammal army vs an irregular dino army. In open field, dinos win as there is little the mammals can do vs these giants (assuming no tech for the mammals). This means that the mammals need to engage in a guerilla warfare battle...hiding,striking, and hiding again. Mammals may also have an extreme night time advantage as im unsure on nocternal dinos.


Mammals might be much better in water than their dino counterparts as whales tip the scale a bit. Sharks are the natural whale predator, however sharks are not usually considered dinosaurs. If you take a blue whale and put it into dinosaur atmosphere conditions, its possible the blue whale is the biggest creature out there. Also good to point out that some massive sea mammals died out prior to the indian subcontinent colliding with asia (theyd be 10 to 15 foot long eels like creatures comimg from a now extinct branch of whales that would dominate a shallow ocean enviroment though weak in deep waters).


by making intelligence equal you basically guarantee a dinosaur victory.
your biggest problem is armor, scutes and scales are tough, dinosaur skin is going to be a lot better armor than mammals have. plus dinosaurs have a much large pool of talent to pull from, the cretaceous is almost 30 times longer than the quaternary. Finally in the end size is just too big an advantage in open combat, some of the armored sauropods would be nigh unstoppable to modern mammals. Or picture Ankylosaurus it weighs as much as an elephant but it comes equipped with both amazing armor and a killer weapon, and it needs it because there are many herbivores and predators much bigger than it. mammals just are not designed to be big so the big ones are kinda fragile.


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