Appendix? However, this is not in the skeleton, but it isn't geology either.
However, since this is not my area of expertise, I searched Google under the key words "vestigial structures humans" to get these possible sources:
In the future, you can find the information you desire more quickly, if you use appropriate key words to do your own search. Also see http://hanlib.sou.edu/searchtools/.
I hope this helps. Thanks for asking.