Cervical Vertebrae in Relation to Roosting Posture in BatsRhinopoma hardwickii and Rhinopoma muscatellum

We examined the cervical vertebrae of the following bats: Penthetor lucasi, Micropteropus pusillus, Hypsignathus monstrosus, Rhinopoma hardwickei, Taphozous melanopogon, Noctilio leporinus, Nycteris thebaica, Rhinolophus affinus, Hipposideros armiger, Macrotus waterhousii, Glossophaga longirostris, Artibeus jamaicensis, Myotis lucifugus, Otomops martiensseni, and Molossus molossus to identify specializations associated with dorso-ventral flexibility. The specializations of the cervical vertebrae of Megachiroptera and Microchiroptera were distinctly different, and none of the species examined shows evidence of an intermediate condition. Specializations for dorso-ventral flexibility included the thickness of the neural arches, the plane of articulation between adjacent centra, the ventral interlocking of adjacent centra, and the angles of articulation reflected by the anterior zygapophyses. These differences correlate with difference in roosting posture because the Megachiroptera typically roost with the head facing ventrad, and many Microchiroptera roost with the head facing dorsad, 180° different from the megachiropteran posture.