As far as I’m aware, Emu’s flap their tiny, stiff wings as a counterbalance whilst running, and to aid in making tight turns. The mental image of a carnotaur doing the same is pretty hysterical.

birdsbugsandbones:

alphynix:

I didn’t know about that – that’s actually really interesting, since Carnotaurus actually did have very mobile shoulder joints.

 @zeroxz21 @alphynix 
Having worked with emus, seen them running, and gotten a real good
look at their wings and the underlying anatomy there, I’m confident in saying they are far too limp and
vestigial to be honestly used for anything. They are not stiff at all, rather they’ve actually seen a dramatic reduction in all the associated muscles compared to other rattites, therefore they are unlikely to be strong enough to use as a rudder. The only supporting literature I can find for emus flapping their tiny, useless wings or using them as a rudder is a 1969 book by Eastman that kind of whimsically postulates it as a possibility. Here’s an emu running flat out, note that the wings are back against the body, hidden in the fluff of their chest:

Here’s about as prominent as the wings get, and I can tell you they are very limp. This girl is displaying so she’s puffed her neck fluff up and let her wings hang forward:

The ‘flapping’ is just the wings moving as the animal moves. Emus tend to  use their head and neck more than anything to steer, resulting in a lot of hilarious throwing of their head about as they attempt to turn around – usually they have to slow and lean their entire body, it’s an entirely ungraceful affair! The reason the wings persist is that they haven’t been selected against in any way, and have just persisted because they have no negative impact on the fitness of the animal. I’ve got no idea how muscled/rigid Carnotaurus forelimbs are, but emu limbs are most certainly not rudders!

I’m pretty sure you could genetically modify emus to remove the wings and it would make absolutely 0 difference to general emu operation.