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A Novel Objective Method of Estimating the Age of Mandibles from African Elephants (Loxodonta africana Africana).

Stansfield FJ - PLoS ONE (2015)

Bottom Line: The importance of assigning an accurate estimate of age and sex to elephant carcasses found in the wild has increased in recent years with the escalation in levels of poaching throughout Africa.These 'Age Reference Lines' were then associated with an age scale based on previous studies and Zimbabwean mandibles of known age.The new ranking produced a single age scale that proved useful for both male and female mandibles up to the maximum lifespan age of 70-75 years.

View Article: PubMed Central - PubMed

Affiliation: The Elephant Research and Conservation Unit, Savé Valley Conservancy, Chiredzi, Zimbabwe.

ABSTRACT
The importance of assigning an accurate estimate of age and sex to elephant carcasses found in the wild has increased in recent years with the escalation in levels of poaching throughout Africa. Irregularities identified in current ageing techniques prompted the development of a new method to describe molar progression throughout life. Elephant mandibles (n = 323) were studied and a point near the distal dental alveolus was identified as being most useful in ranking each jaw according to molar progression. These 'Age Reference Lines' were then associated with an age scale based on previous studies and Zimbabwean mandibles of known age. The new ranking produced a single age scale that proved useful for both male and female mandibles up to the maximum lifespan age of 70-75 years. Methods to aid in molar identification and the sexing of found jaws were also identified.

No MeSH data available.


Related in: MedlinePlus

The Age Reference Line (ARL) ranking, showing the molar progression stage associated with data from previous ageing studies [3, 10].Plateaus can be seen in the graph because some lamellae move through more quickly than others, particularly the smaller ones at each end of molars, and some lamellae may not pass the ARL in occlusal wear (eg M6L1).
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pone.0124980.g005: The Age Reference Line (ARL) ranking, showing the molar progression stage associated with data from previous ageing studies [3, 10].Plateaus can be seen in the graph because some lamellae move through more quickly than others, particularly the smaller ones at each end of molars, and some lamellae may not pass the ARL in occlusal wear (eg M6L1).

Mentions: For age association, all the jaws examined were initially allocated to a Laws [12] age group from photographs of the occlusal surface of the mandibles. The jaws were then re-ranked according to the newly established ARL data. Group mean data on known age jaws from Amboseli Park [3] and mean ages allocated by the Laws [12] parameters were plotted on a graph (Fig 5). A new scale of age based on the Laws [12] and Lee et al. [3] data was then plotted to match the progression of the lamina through the jaw as indicated by the ARL. When relating to elephant age, the term ‘>70’ refers to animals over the age of 70 but with a maximum age of 75 years; ageing during this period may be greatly influenced by natural variation and perhaps diet. The findings in this study were also supported by photographs of molars of live, semi-domesticated elephants of known age (± 1 year) living in Zimbabwe, South Africa and Zambia, the oldest animal being a female of 47 years of age.


A Novel Objective Method of Estimating the Age of Mandibles from African Elephants (Loxodonta africana Africana).

Stansfield FJ - PLoS ONE (2015)

The Age Reference Line (ARL) ranking, showing the molar progression stage associated with data from previous ageing studies [3, 10].Plateaus can be seen in the graph because some lamellae move through more quickly than others, particularly the smaller ones at each end of molars, and some lamellae may not pass the ARL in occlusal wear (eg M6L1).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4430523&req=5

pone.0124980.g005: The Age Reference Line (ARL) ranking, showing the molar progression stage associated with data from previous ageing studies [3, 10].Plateaus can be seen in the graph because some lamellae move through more quickly than others, particularly the smaller ones at each end of molars, and some lamellae may not pass the ARL in occlusal wear (eg M6L1).
Mentions: For age association, all the jaws examined were initially allocated to a Laws [12] age group from photographs of the occlusal surface of the mandibles. The jaws were then re-ranked according to the newly established ARL data. Group mean data on known age jaws from Amboseli Park [3] and mean ages allocated by the Laws [12] parameters were plotted on a graph (Fig 5). A new scale of age based on the Laws [12] and Lee et al. [3] data was then plotted to match the progression of the lamina through the jaw as indicated by the ARL. When relating to elephant age, the term ‘>70’ refers to animals over the age of 70 but with a maximum age of 75 years; ageing during this period may be greatly influenced by natural variation and perhaps diet. The findings in this study were also supported by photographs of molars of live, semi-domesticated elephants of known age (± 1 year) living in Zimbabwe, South Africa and Zambia, the oldest animal being a female of 47 years of age.

Bottom Line: The importance of assigning an accurate estimate of age and sex to elephant carcasses found in the wild has increased in recent years with the escalation in levels of poaching throughout Africa.These 'Age Reference Lines' were then associated with an age scale based on previous studies and Zimbabwean mandibles of known age.The new ranking produced a single age scale that proved useful for both male and female mandibles up to the maximum lifespan age of 70-75 years.

View Article: PubMed Central - PubMed

Affiliation: The Elephant Research and Conservation Unit, Savé Valley Conservancy, Chiredzi, Zimbabwe.

ABSTRACT
The importance of assigning an accurate estimate of age and sex to elephant carcasses found in the wild has increased in recent years with the escalation in levels of poaching throughout Africa. Irregularities identified in current ageing techniques prompted the development of a new method to describe molar progression throughout life. Elephant mandibles (n = 323) were studied and a point near the distal dental alveolus was identified as being most useful in ranking each jaw according to molar progression. These 'Age Reference Lines' were then associated with an age scale based on previous studies and Zimbabwean mandibles of known age. The new ranking produced a single age scale that proved useful for both male and female mandibles up to the maximum lifespan age of 70-75 years. Methods to aid in molar identification and the sexing of found jaws were also identified.

No MeSH data available.


Related in: MedlinePlus