Clifford, A. B., and L. M. Witmer. 2004. Case studies in novel narial anatomy: 2. The enigmatic nose of moose (Artiodactyla: Cervidae: Alces alces). Journal of Zoology 262:339-360.

The facial region of moose Alces alces is highly divergent relative to other cervids and other ruminants. In particular, the narial region forms an expanded muzzle or proboscis that overhangs the mouth. The nose of moose provides a case study in the evolution of narial novelty within a phylogenetically well-resolved group (Cervidae). The function of the nasal apparatus of moose remains enigmatic, and new hypotheses are proposed based on our anatomical findings. Head specimens of moose and outgroup taxa were subjected to medical imaging (CT scanning), vascular injection, gross anatomical dissection, gross sectioning, and skeletonization.

Moose noses are characterized by highly enlarged nostrils accompanied by specialized musculature, expanded nasal cartilages, and an increase in the connective-tissue pad serving as the termination of the alar fold. The nostrils are widely separated, and the rhinarium that encircles both nostrils in outgroups is reduced to a tiny central patch in moose. The dorsal lateral nasal cartilage is modified to form a pulley mechanism associated with the levator muscle of the upper lip. The lateral accessory nasal cartilage is enlarged and serves as an attachment site for musculature controlling the aperture of the nostril, particularly the lateralis nasi, the apical dilatators, and the rectus nasi. Bony support for narial structures is reduced. Moose show greatly enlarged nasal cartilages, and the entire osseocartilaginous apparatus is relatively much larger than in outgroups. The nasal vestibule of moose is very large and houses a system of three recesses: one rostral and one caudal to the nostrils, and one associated with the enlarged fibrofatty alar fold. As a result of the expanded nasal vestibule, osseous support for the nasal conchae (i.e. turbinates) has retracted caudally along with the bony nasal aperture. The nasoturbinate and its mucosal counterparts (dorsal nasal concha and rectal fold) are reduced. The upturned maxilloturbinate, however, is associated with an enlarged ventral nasal concha and alar fold. Moose are the only species of cervid with these particular characteristics, indicating that this anatomical configuration is indeed novel. Although functional hypotheses await testing, our anatomical findings and published behavioural observations suggest that the novel narial apparatus of moose probably has less to do with respiratory physiology than with functions pertaining specifically to the nostrils. The widely separated and laterally facing nostrils may enhance stereolfaction (i.e. extracting directional cues from gradients of odorant molecules in the environment), but other attributes of narial architecture (enlarged cartilages, specialized musculature, recesses, fibrofatty pads) suggest that this function may not have been the evolutionary driving force. Rather, these attributes suggest a mechanical function, namely, an elaborated nostril-closing system.

This specimen (OUVC 9742) is a subadult female collected by the Department of Natural Resources in Newfoundland, Canada. It was killed by accidental collision with a vehicle followed by euthanasia by gunshot; this is evident from the bullet holes in the skull roof and preorbital regions on the left side, and the high-density (bright) bullets and bone fragments visible in the ventral portions of the back of the head.

The specimen was scanned (120.0 kV, 200.0 mA, 5 mm slice thickness, bone algorithm) on 21 May 2002 on a GE HiSpeed Fx-i Helical CT Scanner at O'Bleness Memorial Hospital, Athens, Ohio with the assistance of Heather D. Mayle, RT. The head was then injected (according to procedures modified from Sedlmayr & Witmer, 2002) and re-scanned on 23 May 2002, using the same equipment, settings and personnel. CT data were exported in DICOM format using eFilm (v. 1.5.3, Merge eFilm, Tonoto). Analysis and postprocessing employed eFilm (v. 1.8.3) and Amira (v. 3.0, TGS, Inc., San Diego). Quicktime (v. 6.0, Apple Computer, Inc., Cupertino) was used to make the movies.

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Slice movies optimized for soft tissue.
transverse	sagittal	horizontal

Slice movies with injected arteries.
transverse	sagittal	horizontal

Visualization of nasal airway and skull.