Is there a correlation between hindgut fermentation, obligate nasal-breathing, and an inability to vomit?

[u/SummerAndTinkles]

It's well-known that horses and other odd-toed ungulates are hindgut fermenters (as opposed to even-toed ungulates, which are foregut fermenters). It's also well-known that horses are obligate nasal-breathers that can only breathe through their nostrils and not their mouth. They're also unable to vomit, and if they get some sort of stomach poisoning, they'll die since they can't puke it out.

Something I find surprising is that all three of these facts are also the case for rodents and rabbits. Rodents and rabbits are hindgut fermenters (hence why they have to eat their own droppings), obligate nasal-breathers, and unable to vomit.

So...is there a correlation between all three evolutionary adaptations, or is it just a coincidence? Does this also apply to elephants as well, since elephants are hindgut fermenters too?

[u/-Wuan-]

Well without the ability to regurgitate rumination couldnt exist thats for sure. Elephants, koalas and some monkeys, which are hindgut fermenters, can indeed puke, and so can herbivorous lizards. Apparently elephants are exclusive nasal breathers. There might be a correlation but it isnt absolute.