Fig. 21 in The Mammals Of Paracou, French Guiana: A Neotropical Lowland Rainforest Fauna Part 2. Nonvolant Species

Fig. 21. Detail of auditory region in (A) Marmosops pinheiroi (AMNH 267346) and (B) Marmosa murina (AMNH 267368). In Marmosops, the tympanic wing of the alisphenoid (twa) produces an anteromedial strut (st) that partially encloses the mandibular branch of the trigeminal nerve (V3, reconstructed course shown by heavy arrow); the nerve then emerges from a secondary foramen ovale. In Marmosa, the extracranial course of the nerve is unenclosed by the alisphenoid because the anteromedial strut is absent; there is no secondary foramen ovale in this species. Other abbreviations: als, alisphenoid; bo, basioccipital; bs, basisphenoid; et, ectotympanic; fo, foramen ovale; per, periotic.