Skullyrex

The Skullyrex is an undead skull enemy that first appeared in Donkey Kong Country Returns and Donkey Kong Country Returns 3D. Skullyrexes are essentially Skellirexes without a body and a smaller head. They hop around from left to right while biting, and can be taken out by any attack. A Skellirex also behaves exactly like a Skullyrex when it loses its body.

Reference
Skalettorex