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Cephalometric correlates of echolocation in the chiroptera: II. Fetal development
Author(s) -
Pedersen Scott C.
Publication year - 1995
Publication title -
journal of morphology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.652
H-Index - 74
eISSN - 1097-4687
pISSN - 0362-2525
DOI - 10.1002/jmor.1052250109
Subject(s) - biology , rostrum , skull , human echolocation , anatomy , nasal cavity , ontogeny , oral cavity , occipital bone , fetus , neuroscience , orthodontics , pregnancy , zoology , medicine , genetics , genus
Cephalometry was used to detect patterns of cranial growth in fetal bats that were stained differentially for bone and cartilage. Three developmental features distinguish embryos of taxa that echolocate nasally from embryos of taxa that echolocate orally: (1) the basicranium is retained ventral to the cervical axis, (2) the rostrum is retained below the basicranial axis, and (3) the lateral semicircular canals are rotated caudally. Together, the first two actions align the fetal nasal cavity with what will be the long axis of the adult body in flight. The third action aligns the lateral semicircular canals with the horizontal. In contrast, skulls of oral‐emitting taxa are constructed such that the oral cavity is aligned with the long axis of the body in flight. The evolution of head posture and skull form in microchiropteran bats has been constrained by the demands of vocalization, i.e., ultrasonic echolocation. Accordingly, the ontogeny of the microchiropteran skull has been canalized along two distinct developmental paths—oral‐emitting and nasal‐emitting Baupläne . © 1995 Wiley‐Liss, Inc.