So, I've decided that in my fantasy fiction, I want to have Megabara riders. Massive Capybaras, being ridden into a battle.

I've done some basic research and I came across this extinct species that comes close enough(I still want to keep shorter tail and slightly shorter skull of capybara though): Josephoatigasia


I am however aware that's far from enough. Zebras, similar to horses don't have spine suited for a mounted rider, and it is also known that riding an elephant isn't very healthy for the said elephant. So, apart from size, there are other requirements. So, what anatomical changes do I need for my megabaras to be rideable by (at least lightly) armoured troops?

  • 1
    $\begingroup$ I can’t decide if Megabara cavalry would be cute or horrifying... $\endgroup$
    – Joe Bloggs
    Commented May 29, 2020 at 10:51
  • 2
    $\begingroup$ @JoeBloggs Both. Assuming it has same biteforce as the Jose-not-capybara I found, we're talking about 4 times as much bite force as a tiger. If you're wearing mail or gambeson rather than full plate armour, good luck to you. $\endgroup$ Commented May 29, 2020 at 10:54
  • $\begingroup$ A hump or 2 maybe, I'm considering for the rider and of course the animal, I bet they might choose desert and it would be disastrous to develop a kissing spine halfway ;D $\endgroup$
    – user6760
    Commented May 29, 2020 at 12:43
  • $\begingroup$ I read about something like this yesterday, the author (a horse trainer) said horses spines are perfect for riding whereas an elephants isn't as riders sit above the shoulders by the neck, although their logic seems flawed as elephants are capable of lifting massive amounts. $\endgroup$
    – user69935
    Commented May 29, 2020 at 13:36

2 Answers 2


After a little bit of research, the key word here seems to be domestication.

If we're talking about it from a real standpoint, no animal is truly suited for riding. Some can carry much more weight than others but none of them has evolved with the specific purpose of being ridden by something, not even bred horses.

The first thing you need is for it to be able to carry a fair amount of weight, so that a rider doesn't overexert it. Camels and other ungulates might be one of the best examples due to their examples on good weight bearing capacity and the fact we've been riding some of them for a few centuries.

But the most important thing is doing to them what was done to horses. Horses and zebras are extremely similar species with a number of genetic similarities so great we can still breed them and have viable (although infertile) offspring, but the difference is that the domesticated horses are much more adapted to humans than wild zebras. Same for elephants. The problem isn't only that they're forced to carry unhealthy amounts of weight and work to exhaustion. They're wild, and many are literally broken from a psychological perspective to allow humans to ride them (lots of ethical issues towards shitty people working these to death by exhaustion exist, and for a reason).

So the key here is to:

1-ensure they are strong enough to carry weights superior to what you're forcing them to carry (I'd say make them ungulate and approach their anatomy to a Musk ox, since those can carry around 900kg).

2-domesticate them over hundreds of years to be used to human contact and interact with them more easily, as to reduce the amount of stress caused to the animal when humans ride them.

3-keep them healthy and attent to their needs. Not only it'll make it more ethical, it'll ensure better chances of happier, more relaxed and healthier animals.


The group of rodents to which Josephoartigasia belongs, the Dinomyidae, are actually more ground sloth-like than capybara-like. Pacaranas (their only living relative) do climb, and Phoberomys (one of the only ones known from limb bones) has features suggesting it reared up on its back legs to grab food and feed (and the modern pacarana does this as well). That would probably be very bad for any animal you'd want to ride. In this respect just grabbing and domesticating a giant capybara like the ~100 kg Neochoerus might be a better choice.

Dinomyids do have a stiff cervical skeleton, and if they had a stiff back that would make them really good as riding animals (this is why ungulates usually make good mounts and carnivores with flexibile backs like big cats do not), but I am unaware of any studies discussing how stiff the actual thoracic and lumbar vertebrae of a dinomyid is.

Also, that figure is way too big for Josephoartigasia. The size of Josephoartigasia has been controversial, originally it was suggested to be about 1000 kg but later studies have revised that estimate much lower to about 400 kg. That's only about the size of a pygmy hippopotamus. There is currently no rodent that is uncontroversially larger than about 400 kg. This is a more accurate depiction of Josephoartigasia's size:

enter image description here


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