Are those supposed to be zombies or something?
They're a new enemy in Revelations 2, those specific brand of them are called Revenants. They're sewn-together body parts combined with
, but we don't know all about them yet.
That particular enemy actually is pretty creepy in my opinion, though I've gotten good fighting them in Raid Mode. Basically, one of their limbs randomly is their weak-point (one of their arms, their legs, their torso, or their head), but you cannot see it as their greyed skin block the way, unless you're Natalia and use her enemy sight ability. You have to shoot the limb so their skin peels off and their weak-point will be an orange core connected to their muscle tissue if you shot the correct place. They also can morph their bodies around to take three stances, one is a stance where it comes at you on two limbs (like in the picture above), another has it where it turns its body upside down and goes on five legs and moves super quickly (faster than you), the last is a stance where it charges forward with its knife-like hand extended. A creepy combination of how it looks when it's shifting position, and how limbs of its body can be completely skinless, or the whole thing completely skinless, and it'll still be coming at you until its weakpoint is destroyed.
There's a few other similar enemies to it that haven't been seen in the campaign yet, but can be encountered in Raid Mode. They look and function differently, but obviously the same kind of enemy.