Board Thread:Speculation House/@comment-14138255-20141017020106/@comment-226878-20141017041943

Someone figured a discrepancy in time given the duration for which Mountain Glenn existed and how quickly the location came to ruin. Now we know that the Grimm are a contributing factor. They are not satisfied to kill, but seek to undo the creations man has erected. Although, it would appear they do not desire to return the world to one of complete nature, as they leave remnants of the constructions (i.e. the ruins in the Emerald Forest).

To "skeletal Grimm": insects are the only creatures I can think of that look eternally emaciated due to the fact that they are composed of an exoskeleton. Giant creepy crawlies have long been a popular monster type and that holds up in RWBY given the appearance of the Death Stalker.

So far, our monster types include mammals, reptiles, avians, and arachnids. We could include insects on the list if we had any kind of proof that Rapier Wasps were actually a species of Grimm (for the lay people: arachnids are not insects).