I posted a portion of a shark braincase in this sub-forum on June 7th of 2014 that I had sent to the American Museum of Natural History in November of 2011. Dr. John Maisey is their curator of fossil fishes and the leading expert of Paleozoic sharks so I thought he should be the one to have a look. When he proposed writing a paper on it I donated it to the museum collection. That was September of 2012 and he has just now gotten past peer review with the paper and it will be in the Journal of Vertebrate Paleontology soon. It is already available in their digital edition.
Over 5 years has been a long time to wait but I am very glad I got the chance to make this contribution since it appears to be from the largest known shark of it's time. We still don't know which shark it is but there have been some very large teeth found at the Jacksboro Texas Lost Creek Dam site where this was found so maybe someday we will. A search for shark brain case will bring up some related posts on TFF.
The paper is titled:
A Pennsylvanian ‘supershark’ from Texas , John G. Maisey, Allison W. Bronson, Robert R. Williams & Mark Mckinzie.
Edit: You can view the contribution on the second pinned page at the 15th post.