Fig. 20. Lagostomus maximus AMNHM 80208 in Basicranial Morphology And Relationships Of Antillean Heptaxodontidae (Rodentia, Ctenohystrica, Caviomorpha)

Fig. 20. Lagostomus maximus AMNHM 80208, right auditory region (rev.); stereopair view (with key) in ventrolateral aspect. Extensive meatal growth complicates morphological interpretation. The hypertrophied anterior crus actually forms three-quarters of the elongate definitive meatus, with the mastoid region (and even the exoccipital) completing much of the remaining (posterior) wall (see also fig. 25). The relatively unexpanded tip of the posterior crus can still be identified, separating the tympanic fenestra from the stylomastoid foramen. The large aperture distal to the stylomastoid foramen is the entrance to a short canal for the posterior auricular artery (bristle in canal). Next to it is a long trough, incorporating the original site of the mostly obliterated ventral cleft (ectotympano-ectotympanic suture). On the margin of the stylomastoid foramen another medially directed foramen may be found; this is provisionally regarded as the homolog of posttympanic foramen of Dinomys (C2:2).