FIG. 10 in Exceptional Skull Of Huayqueriana (Mammalia, Litopterna, Macraucheniidae) From The Late Miocene Of Argentina: Anatomy, Systematics, And Paleobiological Implications

FIG. 10. Virtual parasagittal section through choana of skull of Huayqueriana cf. H. cristata IANIGLA-PV 29. Light gray areas within skull represent unremoved matrix. Caudally-situated vacuity between nasal aperture and nasopharynx is here denoted as "true" nasal cavity (tncav), as it would have acted as the most direct air passageway in life. Primitive nasal cavity (mnv, meatus nasi ventralis) persists as a diverticulum, lacking an external aperture at front of rostrum. Note substantial thickness of rostralmost portions of premaxilla/maxilla at front of long, comparatively gracile rostrum. Other abbreviations: chl, cochlea; crh, position of cerebral hemispheres; cerebral cavity; Ec, ectotympanic; fs, frontal sinus; mnv, meatus nasi ventralis; Mx, maxilla; ns?, possible distorted portion of nasal septum; pafs, parietal extension of frontal sinus; plf, palatine fissure; Pmx, premaxilla; sphs, sphenoidal sinus; t, turbinate fragments in caudal portion of nasal cavity; tncav, true nasal cavity.