So basically two people are transported back in time to 66 MYA ago with just their clothes on their back, a month of rations and the time machine that sent them back.

They're going to spend the next three months to a year in the Minnesota area until it's fixed. But they gotta survive the era in the meantime.

I'm going to say they're on a medium sized island that is about twenty-five square kilometres which is surrounded by a seventy-meter-wide river or water body. I dont really know much about what Minnesota looked like at this time. I assume they're in a more woody area with caves or as ideal as you can expect for such an area. I don't know much about the terrain of this era. I wanted to elaborate this a bit more.

There's going to be a scene in my story, where the male protagonist, saves the female protagonist from certain death after the later is ambushed by one such creature. After he kills it, with minor injuries, the two have sex later that nightm

Taking place in Minnesota, 66 MYA, I want to be relatively accurate for the time period. But I also want to be able to show such a huge accomplishment.

It can be a spear, a bow and arrow or even just a club.

What is the largest dinosaur or prehistoric animal can a person, reasonably kill, in self defense?

Given this and the ability to make stone age equipment what kind of animals or dinosaurs could they take down?

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    $\begingroup$ Since they seem unlikely to have immunity to the viruses and other microorganisms of the era, their constant retching and uncontrollable fevered shaking suggest that they won't be able to fight well at all. And the diarrhea suggests a rapid death from dehydration. $\endgroup$
    – user535733
    Commented Jul 9, 2022 at 6:56
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    $\begingroup$ Considering that stone age 'weaponry' included chasing mega fauna like wooly mammoth over cliffs and the use of deliberately set brush fires to do the chasing on occasion if they've a big enough cliff handy the answer is any damn size you want. $\endgroup$
    – Pelinore
    Commented Jul 9, 2022 at 8:41
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    $\begingroup$ If they are fixing the time machine, I'd guess they have some tools with them? Also - and this to me is the more annoying point - if they have a time machine, why wait for 3 months? Why can't someone else come to rescue them right there and then? And if other's don't know where to find them (or don't have a time machine), why don't they - after fixing the time machine - go back and rescue themselves at day zero? Or, if directly rescuing themselves would be too much of a paradox, they could go back and give themselves a crapton of tools and food so that they don't need to worry about survival. $\endgroup$
    – Vilx-
    Commented Jul 9, 2022 at 17:16
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    $\begingroup$ Just a side note, but what strikes me as the most prehistoric part of this setting is the male protagonist saving the female protagonist and having sex afterwards. Of course, it can still made a very good story of the old fashion. $\endgroup$
    – Pere
    Commented Jul 10, 2022 at 9:11
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    $\begingroup$ Lots of huge animals (e.g. ground sloth, whooly mammoth, giant lizards) have been hunted to extinction in the stone age. However, large animals are generally not found on an island because there's not enough food for them. $\endgroup$
    – Joooeey
    Commented Jul 10, 2022 at 11:42

8 Answers 8


For killing something very big, say the size of an elephant, their best bet would be to prepare a trap of some kind.

If there are giant predators stomping around, the humans' first priority would be some place to be safe from them. Perhaps a treehouse or a cliff-side dwelling. This would give them the time they need to construct the traps.

  • A big hole with spikes at the bottom. Downside: takes a long time to dig
  • Forget digging, cover an existing chasm with thin branches and leaves, and lure a large creature to step on them, using a medium-sized carcass as bait. If no chasm is handy, a similar trap might be constructed extending over the edge of a cliff.
  • Build a very sturdy enclosure with a log-cabin style of construction, and lure something big into it. Then drop logs to cover the entrance to trap it. Then stab it to death with long pikes, through the walls.
  • Identify something poisonous - perhaps a plant or a frog. Look for an animal that is brightly colored and seems to have no other way to defend itself - that's probably a poisonous animal. Acquire a lot of the poison and put it in a medium-sized carcass. A giant animal eats the carcass and dies. The giant animal is probably no longer safely edible, but at least it's dead.
  • Snare traps are a possibility if they find a suitable fibrous plant to make rope, and know how.
  • Start a forest fire, killing animals in the forest.

If they have plenty of know-how, they might also try constructing a trebuchet or a torsion catapult. This could launch a projectile hard enough to kill a large beast, assuming the large beast is courteous enough to line up right in front of it. Perhaps it could be set up aimed at a watering hole or a narrow path.

Another option would be to drop a heavy pointy thing on the large animal from safe up in a tall tree. This relies on a good deal of luck, that the large animal passes directly below where you are and that you time the drop perfectly.

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    $\begingroup$ I happened to visit a buffalo jump en.wikipedia.org/wiki/Buffalo_jump and the stone-age tech of native Americans was quite capable of killing entire herds of animals. So even the biggest dinos might be panicked by fire and herded off a cliff. $\endgroup$
    – DWKraus
    Commented Jul 9, 2022 at 12:32
  • $\begingroup$ Added a cdetails to grlp $\endgroup$ Commented Jul 10, 2022 at 7:43
  • $\begingroup$ I'm interested in the log cabin idea. But it seems a large enough beast (e.g. elephant/mammoth) would be able to break through some tree trunks; and if they were tied together with vines or other natural fibers it would be possible to dislodge them. Stakes in the ground to make a fence would also trap some animals, although again probably not an elephant. I'm not sure what would be the practical size limits; probably depends on tree size, but wider than an elephant. It would definitely require thought about construction. It would be easier to do it in a gorge or other narrow place. $\endgroup$
    – Stuart F
    Commented Jul 11, 2022 at 10:21
  • $\begingroup$ @StuartF A log cabin is very heavy construction. I think if you can keep the logs from separating vertically from each other, by interlocking the branches, weaving branches vertically between the logs, and perhaps using vine lashings to help, then the actual logs - like, a dozen 8" logs stacked on top of each other - are not going to break, even if an elephant charges into them. Also, you can sharpen some of the branches in the wall to make spikes to discourage it from trying. Vertical stakes could work too but it's more difficult construction to drive 8" trees deep into the ground. $\endgroup$
    – causative
    Commented Jul 11, 2022 at 16:24
  • $\begingroup$ Digging a trap and waiting for the animal to fall into it doesn't seem heroic enough for the woman to want to have sex with the male protagonist afterwards. Unless she is really into guys who are good at digging holes. $\endgroup$ Commented Jul 12, 2022 at 16:17

Making a stone age weapon is a thing. Being able to use it is another story. Bow and spear take quite some practice to be used effectively, same as an axe or a slingshot.

If your pair pops out of the blue in a remote area, they should be able to hunt something the size of a rabbit with not too much struggle. Anything bigger than that, starting from a goat size, will be challenging at the beginning. If they manage to survive and build up some muscles and technique they might be able to go after them.

Also they will quickly realize than killing something bigger than that might be not that smart: a large corpse attracts scavengers and cannot be easily stored, better go for something which can be quickly butchered and consumed.

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    $\begingroup$ I'm not so sure about the 'rabbit with not too much struggle' part. Do you feel confident you could hit a wild rabbit with a spear or bow and arrow? I'm not sure I would manage. $\endgroup$
    – quarague
    Commented Jul 9, 2022 at 16:29
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    $\begingroup$ I think a better idea would be to set up traps for them rather than try to shoot them. Similar for fishes. $\endgroup$
    – Vilx-
    Commented Jul 9, 2022 at 17:11
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    $\begingroup$ Also, if there's two of you, you could always just try to approach it from either side and then chase it and corner it off from any escape until it tires-- humans are more skilled at distance running compared to a lot of the animal kingdom, it may be possible to simply exhaust it until you can grab it. $\endgroup$ Commented Jul 9, 2022 at 19:21
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    $\begingroup$ Rabbits without too much struggle? I've encountered a decent number of rabbits when I'm out hiking--and only once have I seen one that I would have the slightest chance of getting with anything less than a firearm. They're normally already running when they come into view. $\endgroup$ Commented Jul 9, 2022 at 22:07
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    $\begingroup$ @KerrAvon2055 No, I've never encountered a rabbit in an area hunting was permitted. Typically they bolt when still masked by terrain (uneven ground) and they come into view already running. Only once when I had a substantially longer sight line than usual did I see one not running. You seem to be describing an area with enough humans that always running from them would be impractical. $\endgroup$ Commented Jul 11, 2022 at 3:30

It is not clear from OP if they are killing things in self defense, because they are hungry, or to pass the time. I will assume it is because they are hungry. If you are hungry there is no reason to kill something bigger than you can eat in a day.

Fish, clams and crayfish.

You do not need a lot of tech or a lot of strength to get enough of this sort of meat to fill your belly. Fish traps are not hard to make and once you make them you can use them again and again. You can catch crayfish and clams just picking them up. All of these animals are good human food and much eaten by people for as long as there have been people. Plus you can keep them fresh if you keep them in the water.

Not sure about the leeches of the Cretaceous but Minnesota is well supplied now. I imagine wading around looking for crawdads your characters might wind up with a few. Waste not want not - leeches are good bait!

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    $\begingroup$ wading is less safe when you have 8 meter long crocodiles. I would not encourage wading anywhere south of Alaska during the cretaceous. $\endgroup$
    – John
    Commented Jul 9, 2022 at 14:25
  • $\begingroup$ @John - I wonder if 8 meter long crocodile might be less of a threat than the 3 meter crocodiles that people are wading around with all over the world today. Of course I would rather order in dumplings than wade with crocodiles if that is an option. $\endgroup$
    – Willk
    Commented Jul 9, 2022 at 15:27
  • $\begingroup$ there are smaller crocodilians too, $\endgroup$
    – John
    Commented Jul 9, 2022 at 17:15
  • $\begingroup$ The hard thing about catching mammals is they run away. Reptiles do so, too. Mollusks are great-they stay put so you can catch them. Many grow in dense colonies so are easy to harvest enough as needed. We know oysters can be eaten raw. $\endgroup$ Commented Jul 10, 2022 at 3:24
  • $\begingroup$ @Willk You don't go wading in the parts of Australia where crocodiles live unless you've got a deathwish. $\endgroup$
    – nick012000
    Commented Jul 10, 2022 at 7:41

They will live off of small game (10lbs or less), and fish.

A single fit human with skill can reliably hunt animals up to about a hundred pounds, although risk increases with size, they can kill much larger animals with traps. But hunting dinosaurs will be tricky, they are more familiar with bipedal predators and often armored, and worse their behavior is unpredictable.

humans can make spears, bows, light crossbows and traps relatively easily. With limited or non existent experience small game is probably most likely, animals that weight 10 pounds or less with spears or simple projectiles. These can also easily be hunted with simple traps like snares or deadfalls. 50lb animals with traps is certainly possible, and I would expect a few if they are their for months.

Small game would include birds, mammals, lizards, turtles, small dinosaurs, also dinosaurs lay a lot of eggs so raiding a nest might also be possible. Eggs are one of the few food sources that can be stored.

As others have pointed out if you are on a river fish are an option, note however encountering crocodiles are also a possibility so there is risk associated with that as well. Several papers (my own included) have shown the range of large crocodilians much farther north. And whatever you do do not go swimming.

enter image description here

Keep in mind hunting will be much easier than today, without a human presence there will be a lot more wildlife, that does also mean a lot more predators as well, so hunting is easier but it getting attacked by large wildlife is also more common. It is also worth considering barriers like water may look daunting to a human but may be easily crossable by large dinosaurs.

Another consideration is you have giant crocodiles and lots of tyrannosaurs, there are even arial predators that might see humans as edible, safe shelter is going to be your biggest problem. Fire is about the only defense humans will have so they will be burning a lot, better hope they can build a stone axe.

Another consideration is plants. Normally plants would be a more reliable food source but they are in the cretaceous, no edible plants will be familiar or identifiable. They might find edible fruit with basic toxin testing protocols but this will take days of testing and I would not try it on anything that was not a fruit or seed, even then you should probably cook it.

If their rations include cans, they can easily boil water and plants so that will be one blessing.

Here is a quick and dirty representation of what is around at the time.



  • $\begingroup$ That illustration of Deinosuchus' range seems to correspond pretty well to the Western Interior Seaway, and I found this page of a book on Deinosuchus which theorizes that it lived mainly in "paralic environments representing salt marshes and tidal basins"--is it possible one could avoid the giant crocs by sticking to freshwater rivers? $\endgroup$
    – Hypnosifl
    Commented Jul 10, 2022 at 5:20
  • $\begingroup$ @Hypnosifl Judging by modern-day Saltwater crocs, probably not. They don't hesitate to colonise basically any water source large enough for them to fit into. $\endgroup$
    – nick012000
    Commented Jul 10, 2022 at 7:39

If they need to defend a fixed point (like the time machine worksite), a combination of deterrence, snares, and protective cover may be preferred. The two stranded folks need to sleep and keep watch and fix the time machine and forage...that's a lot of work.

Create a small perimeter around the worksite. Limit the number of access points using cut timber, piled brush, and stakes. Outside the perimeter, burn out all the undergrowth for at least 100m. 300-400m would be preferable, but your two time-travelers might not have enough time to do that. Keeping small game away will also keep their predators away.

Instead of wasting time and effort hunting game, build simple fish traps in the nearby river. Have dinner come to you, and then wait until you are ready.

For your climactic battle with a vicious dinosaur, have your two strong-thewed survivors carefully goad the dinosaur, leading it away from the time machine using spears and atlatl and fire until it succumbs to blood loss on the far side of the island. Snares and trip-lines can help, too.

Good thing both time-travelers were already skilled at making fire, making fish-traps, cleaning fish without a modern knife, making spears, use of an atlatl, and many other vital skills before they entered the time machine.


There is no limit to what size animal they could take down. Stone age people hunted any large mammal successfully including whales.

You don't have to go in and stab it in the heart. Just trap it or stampede it over a cliff or into a mire, or bleed it out. Or get it in the guts and wait for it to die on it's own. Persistence hunting is another way, just get it moving at a run and don't let it rest and it kills itself.

Dinosaurs aren't even as smart as mammals, they'd be much easier if you understood their limitations and strengths.

Any small animal is doable. I've hunted fruit bats with a sling, which is about as stone age as it gets since it's literally a stone. The stone will take out anything including a human within that size range (assuming you can hit anything with a sling).

Big animals are better, you're not really hunting for meat, it's fat you want. You can eat a lean rabbit a day and still die of starvation. Luckily lizards can be very fatty, you can assume dinosaurs are as well.


Anything at all, toxins don't care how big you are

Any weapon that can penetrate the skin, or any morsel of food can be poisoned to bring down any animal alive. Their first big challenge is finding the toxic plant/insect/animal, but as a natural course of finding things which are edible, you will obviously find things which are inedible. This can be done by observing things that the predator avoids eating. Why doesn't the T-rex eat these little animals? Maybe they are poisonous? Herbivores may stay away from certain plants, such as the modern potato plant which has poisonous leaves. It's a blind guess if mushrooms were available because we have no fossils, but those tend to be the most toxic, and if they are not toxic then in large doses they are at least intoxicating and will disorient the animal for an easy kill.

Their second big challenge is tricking the predator's senses, or masking the poison. A dried stomach lining would make a clever scent-proof poison pill if they are careful not to contaminate the outside of the bag with poison-covered fingers.

They don't need brute force, humans won because of our brains.

I will mention that your biggest threat might not be the biggest predator, but the ones who flock or hunt in packs. Killing one large animal in a trap is easy but when they come in force, that's the real danger.


They don't aim for big. They aim for small.

@Wilk has the right answer for as far as it goes, but hunters and gatherers do not live exclusively on meat. The majority, perhaps a large majority, of their food is vegetable.

Assuming that they have either basic survival training or a functional survival manual on the time machine, with only its motion broken, they will identify edible plants, particularly fruit.

  • $\begingroup$ they are not going to find any recognizable fruit in the cretaceous. $\endgroup$
    – John
    Commented Jul 9, 2022 at 14:41
  • $\begingroup$ Hence the need for survival training or a manual. $\endgroup$
    – Mary
    Commented Jul 9, 2022 at 16:34
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    $\begingroup$ Which won't help 66 million years in the past, none of the plants in the manual will be around. $\endgroup$
    – John
    Commented Jul 9, 2022 at 17:16
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    $\begingroup$ except from the description they obviously were not planning on having to survive in the past, and a time machine exists to time travel is common enough for survival manual to be written for them is pretty big leap. $\endgroup$
    – John
    Commented Jul 9, 2022 at 17:20
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    $\begingroup$ A survival manual would still help. The ones I have seen include a section for how to handle unknown foods, specifically walking you through the best steps for testing them. (i.e. try a little on your skin and wait. If there's no reaction, proceed to step 2...) It would also help with basic wilderness survival techniques. $\endgroup$
    – JamieB
    Commented Jul 12, 2022 at 14:01

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