Headcanon that the main reason for the difference in Vulcan and Romulan biology is diet; while Vulcans are strictly vegetarians, Romulans love their meat and most meals include it in some way.
I also feel like based on Rihannsu books and what micheal chabon wrote about Romulans beliefs and religions there would be a strong emphasis on respecting nature and part of this is if you take the life on an animal you must use as much of its body as possible in a useful way.
As a result romulans are actually a big fan of organ meats and even have special recipes for things such as the brains and eyes etc of different animals often treating them as a delicacy.
Also vulcanoids have been shown to have a strong digestive system and add that to a stronger muscular and denser bones (like vulcans romulans are about 2-3 stronger than humans so I see no reason why this couldn’t also apply to jaw strength and stronger bones could easily mean stronger teeth as well) and I think romulan would really enjoy snacking on some cooked bones (they love the marrow inside and the outside bones create a really nice crunchy texture).
Like I’m just imagining a romulan sitting with a bunch of other species happily enjoying a plate of ribs when all of a sudden ‘snap’ as everyone looks in surprise at the romulan who’s wondering why everyone’s staring as they munch away holding a cracked open rib bone.
Also another key biological difference is that we know that romulans lack the inner eyelid of their Vulcan cousins since they no longer lived on a sunny planet. In fact from what we did see of romulus it appeared to be very dark and overcast constantly, so what if Romulans actually evolved to have better low light vision (not full dark vision but they can definitely see better than us). Also I noticed that alot of their ships seem to quite dark inside and at first and I thought this was they just them being dramatic and trying to look intimidating (I still think it is because romulans are definitely dramatic like that) but it could also be that’s just a comfortable everyday light level for them.















