Centaurs?

Ive seen recently some photos with centaur units. I wonder how can i find animations for these as they are typically not archer (for example) or horses. I mean i can find animations for archers (but teh hane 2 legs) or horses for galloping (but they dont shoot arrows or fight with a sword). Can someone clarify this for me?

The "centaur" is a rider with his legs removed on a horse with its head removed. It's pretty much a regular cavalry.