I'm much more familiar with human anatomy, but this piqued my interest.
As best as I can tell, it's basically the anterior limit of the skull and the posterior limit of the nasal cavity, essentially making it a structural part of the olfactory system. I believe it's part of the ethmoid area or mesethmoid area which would make sense given its proximity to the nostrils (at least if there is any sort of similarity to mammals). If it IS similar to mammals, it would be likely that the olfactory nerve travels through foramina in this region on its way back to the brain.
I've had a really difficult time finding a straightforward explanation for this, but that was the best I could logically piece together for the time being. I'm going to keep reading a bit and I'll post if I find anything else.