This is clearly from observing the picture in its rough form. But it looks as if the left shoulder has what looks to be Slags muzzle/beak (Triceratops). The right should looks to be one of the others upper jaw/beak/muzzle. Possibly grimlocks, but I highly doubt it due to the shape, and the previously seen picture of Optimus riding Grimlock into battle.
This is entirely speculation, But from what I can tell, I believe that Michael Bay has introduced DINO KING into the fray. The dino bots combine to form the great Dino King! As I said, this is entirely speculation due to the poor picture posted.
To add to this, the fist on the right hand looks like a spiked tail from a What I would guess to be Slag (Stegosaurus) and the large staff/mace looks to be his spines from along his back as well.
I can only guess this at the moment, But I think that Snarl will become the left arm, Slag will become the right arm. While Grimlock will become the main body and legs. Also, If Swoop is in the fray, I think he would become part of the lower abdomen, while his wings drape around the sides of the thighs and possibly into the front of the combined robot.
Feel free to prove me wrong, as this is all best guess and speculation based on the provided picture.