In any large collection of vertebrate fossils, one of the more common specimen labels will be "unidentified bone fragment". But even an unidentified fragment can provide useful information. The bone shown above, found near the East Dam of DVL, has the following, rather uninspiring label: "Mammalia (larger size), unidentified bone fragment". This might be part of a transverse process or neural spine from a vertebra, and if so is could be from anything from a horse to a juvenile proboscidean. But there are also other possibilities; about the only things we can rule out are animals like rodents and rabbits that don't have any bones at all that are this large.So why is this bone interesting? Note the grooves visible in several places along the margin. Here are some views from different angles:
These nearly-parallel grooves are consistent with gnaw marks from a carnivoran, so this fragment is covered with trace fossils. We can't say with certainty what type of carnivoran made the marks, but they are not particularly large, so it's unlikely we're looking at a huge animal like Arctodus. A medium-sized carnivoran such as a black bear, dire wolf, or coyote is a more likely possibility, or perhaps even a badger; all of these are known from the Diamond Valley Lake deposits.As I've mentioned in previous posts, carnivoran bones are quite rare in the DVL deposits. But we do see evidence of their activity. We haven't yet catalogued all the bite marks that are present on DVL bones, but I suspect we actually have more carnivoran trace fossils than bones in our collection.