The nasal lies before the preorbital, a small bone usually lying along the spine of the premaxillary.
In M. aurantius the premaxillary bones are not in contact, and it differs from woodfordi in several other respects.
When the spines of the premaxillary are very long the upper jaw may be thrust out for a considerable distance.
The nasal bone extends caudad as far as does the premaxillary; they terminate at the anterior border of the orbit.
There are no posterior processes of the premaxillary; thus the line of fusion with the nasals and septo-maxillaries is broad.
The premaxillary bone, which constitutes most of the anterior part of the rostrum, is typically heteromyid in shape.
The numbers of maxillary, premaxillary, and vomerine teeth are summarized in Table 5.
Ventrally the premaxillary makes up the anterior two-thirds of the lateral wall of the incisive (anterior palatine) foramen.
Some teeth on the premaxillary and anterior part of the maxillary are hooked.
The rostral part of the maxillary is compressed laterally, as is the premaxillary.
premaxilla pre·max·il·la (prē'māk-sĭl'ə)
Either of two bones located in front of and between the maxillary bones in the upper jaw of vertebrates.