Also like dinosaurs, the quadrate partially overlaps part of the squamosal in lateral view. The frill consists mostly of the parietal bone and partially of the squamosal. These specimens show a loose union of the squamosal with the quadrate. The squamosal wing to the parietal is large. The skull of the "Acrocanthosaurus atokensis" holotype shows light exostotic material on the squamosal. It is traversed by the squamosal, sphenoparietal, sphenosquamosal, and sphenopetrosal sutures. It consists of a partial right squamosal, possibly of a subadult individual. Near the lower edge of the squamosal a clearly demarcated groove or depression is present. Godefroit in 1999 called it a "secondary dermal squamosal". The lower branch of the squamosal has a rectangular end. The squamosal shows at least five episquamosals. They are actually the posterolaterally extended corners of the squamosal bone. Unlike "B. edeni", the alisphenoid is separate from the squamosal in "B. omurai". The narrowing is caused by an indentation of the outer rim of the squamosal. The edge on the squamosal horns is sharper.