Fossil Friday – traces on a mammoth rib

Organisms don’t exist in a vacuum. The whole concept of an ecosystem emphasizes the interactions between an organism and its environment, including with other organisms. A large organism like a mammoth can have wide-ranging effects on numerous other organisms, even after its death.

The specimen shown above is a partial Colombian mammoth rib from Diamond Valley Lake, currently being prepared by volunteer Tim Dooley. We have a large number of rib fragments such as this one, and at first glance they all look pretty much the same. But under close examination they often tell unique stories.

After removing glue used to stabilize the specimen in the field, we realized this bone has a number of small, circular pits covering its surface:

There are also some rough, pitted areas:

While I’m not 100% sure, I believe these are traces made by scavenging insects or other invertebrates, especially the rough patches in the last photo. I’m a little less certain of the circular holes. They are reminiscent of vertebrate bite marks, but they aren’t paired and are tiny (all are less than 5 mm in diameter), so I think some sort of burrowing or bone-eating invertebrate is more likely.

Marks such as these are quite common on DVL bones, and may eventually give us some insight into the invertebrate fauna from the valley, which left us almost no body fossils.

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