A general idea.
The lighter pink parts are where the more advanced feathers attach on avian and non-avian dinosaurs.

Primaries don't just droop off of the wrist,leaving the hands naked, they attach to the second finger. The only time this doesn't happen, so far, is with Ornithomimosaurs, who lack Primaries(the ones attaching to the second finger)


Theropod dinosaur hands also don't sit on the ground or face downwards in a mantis-like position.. Ever really. The palms face inward and don't really rotate, though they can flex back towards the forearm to varying degrees.


They are Clappers not Slappers