Bigger bones more obvious and have received the most treatment, not only because they are visible while digging, but also because they are highly valued in most societies, meat, fat, pets, etc., and they are large, and form important parts of staples in most societies. Studies of decomposing bones as well as animal scavenging of bones have had an impact. Gnaw marks, cut marks suggest butchering, but most make sure it is not river wear. See this pattern in the midden dumps. Many groups were forced to distribute pieces of meat to all in a community, this should look different than one family cutting up and freezing a whole animal to use through the winter.
Animals symbolize social distinctions.
Unusual pets conferred status in antiquity. Named and personally owned. There are also many mythic meanings associated with animals in all societies. Often see totemic, important animals in human burials. I excavated one this summer in Bolivia of an old woman who had a bird of prey in the entrance of her chamber.