abnormal basisphenoid bone morphology basisphenoid bone foramen hole in basisphenoid bone MP:0004463 the presence of one or more holes in part of the base of the cranium between the basioccipital and the presphenoid, which usually ossifies separately in the embryo or in the young, and becomes a part of the sphenoid in the adult; in many animals it persists as a separate bone between the basioccipital bone and the presphenoidal bone basisphenoid bone hole MPheno.ontology