The Beasts have strength and toughness, suitable for good physical labour, but without complex hand structures have trouble with fine tasks. They are the working class, and perform physical labour and serve as the men of the military. Special status is afforded to those who find particularly effective skeletons, getting higher order positions. Those with the extreme good fortune to find dragon bones become the Dragon Guard, who protect the nobility of the species, due to being phenomenally strong and almost impossible to decorporate. The Men are determined by those who had the good fortune to incorporate a skeleton with at least one hand. Being plants, all these animals tend to look a little alike, so as far as they are concerned, having useful hands as in opposable thumbs makes you a man. These are the middle class professionals and upper class, for their ability to do fine labour and wield weapons at a higher order. The more man-like you are, the higher a rank you hold, because of your ability to use and adapt their technology to suit your purposes. Mixing skeletons is considered a grave offense. You find one and you use it, and you don't fuck about assembling it or it's the moral equivalent of necromancy. There's also ones who make themselves of metal, using 'bones' forged by men. They are considered to be extremely dangerous, because of their resilience, and completely unnatural, because theiur crime is well beyond making your own skeleton, but making your own bones. That their bones bend and stay bent is the sign of their evil, and that they rust and seep out the essence of their corporation is the sign of their corruption. They are treated not unlike vampires.