The outer wall of the braincase becomes the alisphenoid and the dermal skull bones.
The fourth shot struck the skull above the occipital condyle and entered the braincase; it likely caused instantaneous loss of consciousness and death due to massive brain trauma.
In contrast with the gorgonopsians, the jaw musculature in early therocephalians expanded dorsally over the braincase, leaving only a narrow sagittal crest between the adductor chambers.
The bulk of the muscle mass was located in an adductor chamber between the braincase and the dermal skull bones.
This reduces the importance of the stapes in supporting the braincase ventrally.