scholarly journals Age determination in Cape Mountain Zebras Equus Zebra Zebra in the Mountain Zebra National Park

Koedoe ◽  
1982 ◽  
Vol 25 (1) ◽  
Author(s):  
B. L Penzhorn
Keyword(s):  
Age Estimation ◽  
National Park ◽  
Age Determination ◽  
Tooth Wear ◽  
Tooth Eruption ◽  
Determination Method ◽  
Age Classes

The sizes of foals up to two years old can be used for age estimation in the field. Tooth eruption and replacement, which is similar to Hartmann and plains zebras, can be used for age estimation up to four years. No age classes based on tooth wear could be defined, due to the paucity of material. Infundibula in the incisors are retained to a greater age than in Hartmann or plains zebras. Cementum layer counts offer a reliable age determination method, at least up to 15 years.

scholarly journals Notes on age determination, growth and measurements of Brown Hyaenas Hyaena Brunnea from the Kalahari Gemsbok National Park

Koedoe ◽  
1982 ◽  
Vol 25 (1) ◽  
Author(s):  
M.G.L Mills
Keyword(s):  
National Park ◽  
Age Determination ◽  
Tooth Eruption ◽  
Distribution Range ◽  
The Other ◽  
Body Measurements ◽  
Age Classes ◽  
Full Size ◽  
Adult Age ◽  
Different Parts

Brown hyaenas were aged on the basis of tooth eruption and wear and five age-classes were recognised. Weights and seven different body measurements were recorded from 38 immobilised hyaenas. Full size is reached at the age of 30 months, but age-class 5 animals were significantly lighter than were animals from the other adult age-classes. This was probably due to the worn down premolars of old animals resulting in less efficient bone chewing. With a few puzzling exceptions the sizes of brown hyaenas from different parts of their distribution range are similar.

scholarly journals Incisor tooth wear and age determination in mountain gorillas from Volcanoes National Park, Rwanda

2018 ◽  
Vol 167 (4) ◽  
pp. 930-935 ◽  
Author(s):  
Jordi Galbany ◽  
Thadée Muhire ◽  
Veronica Vecellio ◽  
Antoine Mudakikwa ◽  
Aisha Nyiramana ◽  
...  
Keyword(s):  
National Park ◽  
Age Determination ◽  
Tooth Wear ◽  
Incisor Tooth ◽  
Mountain Gorillas

Mortality Estimation: Biased Results from Unbiased Ages

1984 ◽  
Vol 41 (12) ◽  
pp. 1843-1847 ◽  
Author(s):  
Jay Barlow
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Age Estimation ◽  
Age Determination ◽  
Mortality Rates ◽  
Age Classes ◽  
Estimation Errors ◽  
Mortality Estimation ◽  
Age Estimates

Estimates of mortality rates from age distributions are biased by imprecision in age estimation, even if age estimates are unbiased. I have derived a method for predicting the magnitude of this bias from information on the precision of age determination. Monte Carlo simulations show that bias can be accurately predicted. The commonly used Chapman–Robson mortality estimator is shown to be robust to imprecision in age determination if all age-classes are included. Errors are likely, however, if one or more age-classes are excluded or if other mortality estimators are used. Biases can be corrected if the distribution of age-estimation errors is known.

Age estimation of wild boar based on molariform mandibular tooth development and its application to seasonality at the Mesolithic site of Ringkloster, Denmark

2007 ◽  
Author(s):  
Richard Carter ◽  
Ola Magnell
Keyword(s):  
Wild Boar ◽  
Age Estimation ◽  
Roe Deer ◽  
Tooth Development ◽  
Tooth Wear ◽  
Tooth Eruption ◽  
Faunal Remains ◽  
Wild Game ◽  
Animal Populations ◽  
Different Populations

Age estimation based on the dentition of animal remains is one of the most important methods used for analysis of the demography of past as well as contemporary animal populations by zooarchaeologists and wild game biologists (Wagenknecht 1967; Silver 1969; Morris 1972; Wilson et al. 1982). By constructing age profiles from faunal remains it is possible to study hunting of wild boar and pig husbandry in past societies (Higham 1967a; Rolett & Chiu 1994; Vigne et al. 2000a; Magnell 2005a). Age estimation can also be used for assessing seasonal occupation of settlements and slaughtering of pigs (Legge & Rowley-Conwy 1988; Rowley-Conwy 1993, 1998; Ervynck 1997). Several contributions to this volume provide good examples of how different aspects of the past relationship between humans and pigs can be understood from estimations of age. Age estimations based on tooth development have several advantages over ageing methods based on tooth eruption and wear. Experiments with undernourished pigs have shown that the tooth development is less affected by environmental factors than tooth eruption (McCance et al. 1961). A problem with age estimation of domestic animals based on tooth eruption is that the ages at eruption are known to vary between different breeds (Habermehl 1961; Silver 1969; Reiland 1978; Bull & Payne 1982). The rate of tooth wear is also variable between, and within, different populations as a result of several factors such as variation in tooth morphology, eruption, coarseness, and abrasives in the diet (Healy & Ludwig 1965; Grant 1978, 1982; Deniz & Payne 1982; Magnell 2005b). However, tooth development seems to vary less between different populations. In cattle, roe deer, and red deer no consistent differences between various breeds/populations or between males and females have been noted in tooth development (Brown et al. 1960: 27; Carter 2001a). An advantage with age estimation based on tooth development is that the method considers several definable stages in the formation of all molariform teeth. Because the method is based on several characteristics in the dentition it is possible to give a very accurate assessment of dental maturity and the age of a specimen.

scholarly journals Is Continuous Eruption Related to Periodontal Changes? A 16-Year Follow-up

2021 ◽  
pp. 002203452199936
Author(s):  
C. Wiedemann ◽  
C. Pink ◽  
A. Daboul ◽  
S. Samietz ◽  
H. Völzke ◽  
...  
Keyword(s):  
Tooth Wear ◽  
Total Sample ◽  
Population Based ◽  
Tooth Eruption ◽  
Reference Points ◽  
3 Dimensional ◽  
Probing Depth ◽  
Molar Teeth ◽  
Using Data

The aims of this study were to 1) determine if continuous eruption occurs in the maxillary teeth, 2) assess the magnitude of the continuous eruption, and 3) evaluate the effects of continuous eruption on the different periodontal parameters by using data from the population-based cohort of the Study of Health in Pomerania (SHIP). The jaw casts of 140 participants from the baseline (SHIP-0) and 16-y follow-up (SHIP-3) were digitized as 3-dimensional models. Robust reference points were set to match the tooth eruption stage at SHIP-0 and SHIP-3. Reference points were set on the occlusal surface of the contralateral premolar and molar teeth, the palatal fossa of an incisor, and the rugae of the hard palate. Reference points were combined to represent 3 virtual occlusal planes. Continuous eruption was measured as the mean height difference between the 3 planes and rugae fix points at SHIP-0 and SHIP-3. Probing depth, clinical attachment levels, gingiva above the cementoenamel junction (gingival height), and number of missing teeth were clinically assessed in the maxilla. Changes in periodontal variables were regressed onto changes in continuous eruption after adjustment for age, sex, number of filled teeth, and education or tooth wear. Continuous tooth eruption >1 mm over the 16 y was found in 4 of 140 adults and averaged to 0.33 mm, equaling 0.021 mm/y. In the total sample, an increase in continuous eruption was significantly associated with decreases in mean gingival height ( B = −0.34; 95% CI, −0.65 to −0.03). In a subsample of participants without tooth loss, continuous eruption was negatively associated with PD. This study confirmed that continuous eruption is clearly detectable and may contribute to lower gingival heights in the maxilla.

scholarly journals Validation of Age Estimation in the Harp Seal, Phoca groenlandica, Using Dentinal Annuli

1983 ◽  
Vol 40 (9) ◽  
pp. 1430-1441 ◽  
Author(s):  
W. D. Bowen ◽  
D. E. Sergeant ◽  
T. Øritsland
Keyword(s):  
Outer Layer ◽  
Age Estimation ◽  
Transverse Section ◽  
Age Determination ◽  
Middle Layer ◽  
Harp Seal ◽  
Growth Layer ◽  
Phoca Groenlandica ◽  
Incremental Growth ◽  
Absolute Age

We investigated the validity and accuracy of age estimation in harp seals, Phoca groenlandica, using a sample of 155 known-age teeth from seals age 3 mo to 10 yr. Under transmitted light, transverse sections of harp seal canine teeth showed distinct incremental growth layers (IGLs) in the dentine. The first growth-layer group (GLG), representing Ist-year growth, consists of two IGLs: an outer layer of opaque dentine, bounded by the neonatal line, and an inner layer of translucent dentine. Subsequent GLGs, each representing 1 yr of growth, generally consist of three IGLs: an outer layer of interglobular dentine deposited during the annual molt in April, a middle layer of opaque dentine formed during the northward spring migration (May–June), and an inner layer of translucent dentine formed from July to March. We show that dentinal GLGs can be used to estimate the absolute age of harp seals. The accuracy of the method decreases with age. Only 72.4% of estimates of 0-group seals were correct using only transverse sections. These errors were virtually eliminated (99.0% correct age determination) when the tooth root was examined. Based on a single examination of a transverse section, the probabilities of correctly estimating age are 0.983, 0.889, 0.817, and 0.553 at ages 1, 2, 3, and 4 + yr, respectively, when clearly inaccurate tag-tooth associations are omitted. The respective probabilities are only slightly higher when age is based on the average of five blind readings, being 1.0, 0.889, 0.833, and 0.625. Beyond age 3 yr, existing data are insufficient to estimate reliably the accuracy of age determined by counting GLGs.

Age determination in dogs using ocular light reflection, dental abrasion and tartar

2015 ◽  
Vol 43 (05) ◽  
pp. 317-322
Author(s):  
K. Failing ◽  
R. Neiger ◽  
K. Gesierich
Keyword(s):  
Logistic Regression ◽  
Standard Deviation ◽  
Age Estimation ◽  
Regression Models ◽  
Age Determination ◽  
Light Reflection ◽  
Animal Shelters ◽  
Large Standard Deviation ◽  
Logistic Regression Models ◽  
Final Equation

SummaryObjective: The knowledge of an animal’s age is important for disease probability, prognoses, or epidemiological questions, but unfortunately, it is often unknown for dogs in animal shelters. A simple estimating procedure is preferable being quick and easy to perform, even for nonveterinarians. Material and methods: In 295 dogs the dimension of light reflection (diameter in millimetres), visible on the posterior lens capsule using a penlight, the grade of dental abrasion and dental tartar were documented photographically and the exact weight and age in days were obtained. These photographs were evaluated blinded. The dogs were divided randomly into two groups. The first group was used to establish a model for age determination using linear and logistic regression models considering the documented parameters, which was then validated with the data of the second group. Results: The size of ocular light reflection and age correlated significantly (r = 0.781; p < 0.001; sy,x = 2.45 years [SD of y for given x]). The linear regression model gave the final equation: Estimated age [months] = 13.954 + 33.400 × lens reflection [mm] + 8.406 × dental abrasion [grade] + 8.871 × tartar [grade] with a standard error of estimation of 2.26 years. Conclusion and clinical relevance: Age determination, even based on three parameters results in a large standard deviation making age estimation in dogs very crude.

scholarly journals How Precise are Size-Based Age Estimations in the Sand Lizard (Lacerta Agilis)?

2011 ◽  
Vol 56 (1-4) ◽  
pp. 11-17 ◽  
Author(s):  
Bartosz Borczyk ◽  
Łukasz Paśko
Keyword(s):  
Growth Rate ◽  
Body Size ◽  
Life Span ◽  
Age Estimation ◽  
The Body ◽  
Average Error ◽  
Ecological Studies ◽  
Age Classes ◽  
Sand Lizard ◽  
Lacerta Agilis

How Precise are Size-Based Age Estimations in the Sand Lizard (Lacerta Agilis)?Reptiles show a positive correlation between age and body size and it is common practice to infer the age of an animal from its size. However, the growth rate often differs between individuals, thus such practice may lead to false conclusions. Because age of an animal is a very important factor in many ecological studies, it should be determined with a minimum of error. Here, we compare the body size distribution among different age classes of the sand lizard (Lacerta agilis) to infer if it is possible to correctly determine their age on the basis of the body length. Our results show that the average error in age estimation on the basis of the lizard size is 1.36 year which is approximately 1/3 the average sand lizard life span.

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