The auricular surface

Posted by Henry Scragg on

The auricular surface is locatated on the hip bone and is a kidney bean shape which can help determine age at time of death. Age estimation in the auricular surface of the ilium has been, to date, a heavily researched method due to the fact the auricular surface is more robust and durable the pubic syntheseal.
There have been many methods proposed to make it more precise and easier to use in a forensic anthropology setting. The two most common methods were proposed by Lovejoy et al. (1985) using an 8 phase, descriptive setting and by Buckberry and Chamberlin (2002).

In forensic and paleodemographic contexts, age estimation is one of the most important parameters to create a biological profile, next to sex determination.
Estimating age at time of death differs with age. In children, the methods used are; Dental development; fusion of immature bones and epiphyseal union with dental development being the most effective.

When determining age in a forensic situation, an age range has to be narrow enough to be relevant but also be wide enough to include the actual age of an individual. This is especially relevant in cases such as missing persons.
When creating a biological profile for the auricular surface, the following characteristics are analysed for morphological changes;

Transverse Organisation: This terminology refers to billowing (undulations and transverse ridges) and striae (thin lines or scrapes). Billowing is at its most prominent when the individual is younger. It is then replaced with striae by around the age of 25 – 30.
Striae then stays present on the auricular surface until around the age of 40 and are more marked on the lower face.
Surface Texture: During the early stages of life, the auricular surface is finely granular (grains less than 0.5mm) which over time becomes coarser (grains above 0.5mm) and finally turning to dense bone (smooth nodules of bones with no granularity).
Microporosity: This refers to porosity of the sub-chondral with the perforations being less than 1mm in diameter. This may occur on one or both demifaces.
Macroporosity: Macroporosity is similar to microporosity but with the difference that the perforations are greater than 1mm in diameter.
Apical Changes: Until the age of around 35, the apex tends to be sharp. After this time, arthritic lipping occurs causing it to become broader. The apex is the anterior angle of the auricular surface and is situated at the termination of the articulate line.
Retro-auricular Activity: This area tends to be smooth in young specimens, but age causes there to be an increase in osteophytes, surface irregularity and porosity. This area is to be used only in conjunction with other features of the auricular surface as it is not a clear indicator of age. It is only used with the Lovejoy method and not the Buckberry and Chamberlain method


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