Most of the postorbital bar is made up of the postorbital bones, which are very robust relative to other cryptodontians as in other geikiids.
However, compared to other geikiids, the postorbital bar of Bulbasaurus is relatively smooth and free of bosses.
The sides of the postorbitals, which would have anchored jaw musculature, are very concave.
Near the back, the postorbitals curve and converge to form a somewhat pinched intertemporal bar that overlaps the parietal bones to varying extents.
The squamosal bones also contribute to the postorbital bar; its back edge along the postorbital bar is somewhat twisted in Bulbasaurus, which is seen in other cryptodontians but is taken to an extreme by Aulacephalodon and Pelanomodon, where the bone has become entirely twisted such that the interior faces outwards.
Projections of the squamosal bones partially surround the posttemporal fenestrae on the rear of the skull, like Aulacephalodon, Pelanomodon, Oudenodon, and Tropidostoma.

As for the underlying parietals themselves, they are slightly concave.
In front of the parietals are the small midline preparietal bones, which are relatively broad and have a rounded tip, as in Aulacephalodon and Pelanomodon but in contrast to Tropidostoma.
The pineal foramen is bordered by the preparietals and parietals, and it is surrounded by a simple ridge instead of being on a raised boss like either the large rhaciocephalids and Endothiodon or some large specimens belonging to Aulacephalodon.
On the braincase, no sutures are visible, suggesting that the bones are very fused.
The occipital bones are likewise very fused.
The contribution of the supraoccipital bones to the back of the skull is unusually extensive and occupies much of the area not part of the squamosals above the level of the foramen magnum.
Also unusual are the smaller elements at the back of the skull, namely the postparietals and tabulars.
The postparietals are not part of the continuous flat surface at the back of the skull, instead forming a sharp divot; additionally, a strong midline crest is present on the postparietals and do not extend onto other bones.
Meanwhile, the tabulars are wider than they are long.
Most of the postorbital bar is made up of the postorbital bones, which are very robust relative to other cryptodontians as in other geikiids. However, compared to other geikiids, the postorbital bar of Bulbasaurus is relatively smooth and free of bosses. The sides of the postorbitals, which would have anchored jaw musculature, are very concave. Near the back, the postorbitals curve and converge to form a somewhat pinched intertemporal bar that overlaps the parietal bones to varying extents. The squamosal bones also contribute to the postorbital bar; its back edge along the postorbital bar is somewhat twisted in Bulbasaurus, which is seen in other cryptodontians but is taken to an extreme by Aulacephalodon and Pelanomodon, where the bone has become entirely twisted such that the interior faces outwards. Projections of the squamosal bones partially surround the posttemporal fenestrae on the rear of the skull, like Aulacephalodon, Pelanomodon, Oudenodon, and Tropidostoma.
As for the underlying parietals themselves, they are slightly concave. In front of the parietals are the small midline preparietal bones, which are relatively broad and have a rounded tip, as in Aulacephalodon and Pelanomodon but in contrast to Tropidostoma. The pineal foramen is bordered by the preparietals and parietals, and it is surrounded by a simple ridge instead of being on a raised boss like either the large rhaciocephalids and Endothiodon or some large specimens belonging to Aulacephalodon. On the braincase, no sutures are visible, suggesting that the bones are very fused. The occipital bones are likewise very fused. The contribution of the supraoccipital bones to the back of the skull is unusually extensive and occupies much of the area not part of the squamosals above the level of the foramen magnum. Also unusual are the smaller elements at the back of the skull, namely the postparietals and tabulars. The postparietals are not part of the continuous flat surface at the back of the skull, instead forming a sharp divot; additionally, a strong midline crest is present on the postparietals and do not extend onto other bones. Meanwhile, the tabulars are wider than they are long.
Bulbasaurus