Editing Probainognathus (section)

=== Skull ===
[[File:Probainognathus Skull in Palatal View.jpg|thumb|Illustration of the skull in palatal view]]

The snout of ''Probainognathus'' extended beyond the [[premaxillary]] processes, and was very thin. The apparent fragility of this structure has led to it being broken off several specimens, and has led to an increased difficulty in studying it.<ref name="Romer1970"/> There are several features that have been identified, however. The suborbital arch and the [[zygomatic arch]] were both shaped relatively sharply, and there was an extension of the squamosal posteriorly on the zygomatic arch. ''Probainognathus'' had a long [[secondary palate]] as it stretched all the way to the posterior end of the tooth row.<ref name="Romer1970"/> The secondary palate was formed largely by the palatine, and it was somewhat narrow. This narrowing of the [[palate]] allowed for the conservation of space to be able to fit the back, lower postcanine teeth. Moreover, the [[vomer]] stretched posteriorly to the secondary palate, and significant [[pterygoid bone|pterygoid]] flanges were present, as well.<ref name="Romer1970"/>

The skull of ''Probainognathus'' was on average around {{Convert|7|cm|in}} in length, and lacked the [[pineal foramen]].<ref name="Romer1970"/> The skull was broad in proportion to its length, the face was short and narrow, but its zygomatic region was relatively large, seemingly for jaw muscle attachment.<ref name="Romer1970"/> The skull also possessed a double occipital condyle, which is a typical mammalian feature.<ref name="Colbert1991">Colbert, E., & Morales, Michael. (1991). Evolution of the vertebrates : A history of the backboned animals through time (4th ed.). New York: Wiley-Liss.</ref> In comparison to close relatives, such as ''[[Chiniquodon]]'', the [[braincase]] of ''Probainognathus'' was broader in the [[Parietal bone|parietal]] region, and the occipital region of the skull was deeper. Likewise, the parietals had more depth, the [[occipital]] crest was higher, and the orbits were proportionately larger relative to the rest of its head. The [[sagittal crest]] was also lengthened posteriorly, and split into the occipital crests. This led to a straighter posterior margin, and a more concave occiput in ''Probainognathus''.<ref name="Romer1970"/>