Distinct annuli in cementum, a mineralized tissue surrounding the root of mammalian teeth, are used to estimate age in wildlife. Life-history information may be recorded in cementum patterns but interpretation is complicated by variation in cementum width between individuals, among their teeth, and around the surface of the root. First premolar teeth from polar bears (Ursus maritimus) were evaluated. We identified sources of variation in cementum growth and methods are presented that reduce error and permit comparisons within and between individuals. A minimum of 10 measurements from 1 aspect was required to produce precise estimates of cementum growth layer group (GLG) width. Variance component analysis revealed that comparisons between distal and mesial aspects of the root introduced the greatest variation among bears. Controlling for aspect, variance was partitioned differently between the mesial and distal surfaces. Comparisons between maxillary and mandibular premolars from the same bear indicated that data from these teeth should not be pooled; data collected from left and right lower premolars may be combined. Indices to represent adjusted GLG widths are described that reduce age and allometric effects, allowing life-history or environmental factors to be compared.
You have requested a machine translation of selected content from our databases. This functionality is provided solely for your convenience and is in no way intended to replace human translation. Neither BioOne nor the owners and publishers of the content make, and they explicitly disclaim, any express or implied representations or warranties of any kind, including, without limitation, representations and warranties as to the functionality of the translation feature or the accuracy or completeness of the translations.
Translations are not retained in our system. Your use of this feature and the translations is subject to all use restrictions contained in the Terms and Conditions of Use of the BioOne website.