Odd. It looks as if your pedals have been put on the wrong sides of the bike.

In the second picture of your post, the little triangle is facing toward the front of the bike. Those are usually at the bottom of the pedal (like yours) but on the rear of the pedal.

So, I think your pedals have been mixed up. I don't know what you can do in that case, as the thread are quite possibly toast if try to take the pedals off. Either way, the cages would mount on that bit projecting from the front of the pedal in the fourth picture. I don't know where to get cages with that particular pattern.