Title Considerations of anatomy, morphology, evolution, and function for narwhal dentition
Author Nweeia, M.T.; Eichmiller, F.C.; Nutarak, C.; Eidelman, N.; Giuseppetti, A.A.; Quinn, J.; Mead, J.G.; K'issuk, K.; Hauschka, P.V.; Tyler, E.M.; Potter, C.; Orr, J.R.; Avike, R.; Nielsen, P.; Angnatsiak, D.
Author Affil Nweeia, M.T., Harvard University, School of Dental Medicine, Boston, MA. Other: Community of Mittimatilik, Nunavut, Canada; Delta Dental of Wisconsin; National Institute of Standards and Technology; Smithsonian Institution; Community of Qaanaaq, Greenland; National Institutes of Health; Fisheries and Oceans Canada, Canada; Community of Uummannaq, Greenland
Source p.223-240, ; Smithsonian at the poles, Washington, DC, May 3-4, 2007, edited by I. Krupnik, M.A. Lang and S.E. Miller. Publisher: Smithsonian Institution Scholarly Press, Washington, DC, United States. ISBN: 978-0-9788460-1-50-9788460-1- X
Publication Date 2009
Notes In English. 36 refs. Ant. Acc. No: 86090
Index Terms Southern Ocean; anatomy; behavior; biologic evolution; Cetacea; Chordata; ecology; Eutheria; habitat; International Polar Year 2007-08; IPY 2007-08 Research Publications; Mammalia; morphology; physiology; teeth; Tetrapoda; Theria; Vertebrata
Abstract Interdisciplinary studies of narwhal cranial and tooth anatomy are combined with Inuit traditional knowledge to render a more complete description of tooth-related structures and to propose a new hypothesis for tusk function in the adult male. Gross anatomy findings from computed tomography (CT) and magnetic resonance (MR) imaging and dissections of an adult male and female and one fetus, four to six months in development, were documented. Computed tomography scans rendered images of the tusks and vestigial teeth and their shared sources of innervation at the base of the tusks. Paired and asymmetrical tusks and vestigial teeth were observed in all three samples, and their relative positions reversed during development. Vestigial teeth shifted anteriorly during growth, and the developing tusks moved posteriorly as they developed. Examination of tusk micro-anatomy revealed the presence of a dentinal tubule network with lumena approximately 2 micrometers in diameter and 10-20 micrometers apart over the pulpal and erupted tusk surfaces. Orifices were present on the cementum surface indicating direct communication and sensory capability from the environment to the inner pulpal wall. Flexural strength of 95 MPa at mid tusk and 165 MPa at the base indicated resistance to high flexural stresses. Inuit knowledge describes a tusk with remarkable and combined strength and flexibility. Elder observations of anatomy are described by variable phenotypes and classified by skin coloration, sex, and tusk expression. Behavioral observations of males leading seasonal migration groups, nonaggressive tusk encounters, and frequent sightings of smaller groups separated by sex add to the discussion of tusk function.
URL http://hdl.handle.net/10088/6819
Publication Type monograph
Record ID 292167