A single nasoturbinal extends from this region anteriorly along the roof of the nasal cavity.
The function of the nasoturbinal is the least consistent among mammals, and its relationship with endothermy the most ambiguous.
The nasoturbinal probably represents a forward extension of the ethmoturbinals, which guides air toward the olfactory region.
The most dorsal of these ridges continues anteriorly onto the nasal and supports the nasoturbinal. In some mammals, the nasoturbinal is supported by two closely parallel ridges, separated by a narrow canal that conveys blood vessels.
Furthermore, the nasoturbinal ridges of modern mammals are often grooved to provide space for blood vessels, and their location generally corresponds with that of the grooved ridges in pelycosaurs.
Furthermore, Tatarinov (1963) pointed out that the ridges figured by Orlov are grooved and are comparable to paired nasoturbinal ridges found in more advanced therapsids and mammals.
In both Lystrosaurus and Pristerodon the ridges are paired and closely resemble the nasoturbinal ridges of other therapsids.
However, in a recently prepared specimen of the primitive therocephalian Glanosuchus (GS M796), an additional ridge occurs ventral to the nasoturbinal ridge on the lateral wall of the nasal cavity.
It is located well below the clearly recognizable nasoturbinal ridge and immediately anterior to the anterior process of the lacrimal, which contains the opening of the nasolacrimal canal.
In at least two specimens of the Middle Triassic gomphodont Massetognathus (MCZ 4219 and MCZ 4240), a pronounced ridge is present ventral to the nasoturbinal ridge, in the anterior portion of the nasal cavity.
The nasoturbinal ridges in Massetognathus are largely similar to those in other cynodonts.
The ridges of the olfactory ethmo- and nasoturbinals are restricted to the posterodorsal portions of the nasal cavity, above the transverse lamina, and away from the respiratory pathway.