Fig. 5
From: Creating diversity in mammalian facial morphology: a review of potential developmental mechanisms
Schematic diagram depicting potential developmental mechanisms regulating facial length in bats. Top row: A long face possessed by some nectarivorous bat species (e.g., Choeronycteris mexicana) is formed through extension of the period of facial bone (e.g., premaxilla, maxilla, and dentary) development. Middle row: A short face possessed by many insectivorous or omnivorous bat species (e.g., Macrophyllum macrophyllum) is formed through shortening the period of facial bone development. Bottom row: A truncated face possessed by some frugivorous bat species (e.g., Centurio senex) is formed through deficient outgrowth of the facial processes in pharyngula stages. This could be attributed to reduced proliferation as well as disrupted migration of cranial neural crest cells (ectomesenchyme) occupying the internal space of the facial processes. FNP, frontonasal process; MAN, mandibular process; MAX, maxillary process