Schreger angle
Definition
The acute angle formed at the intersection of two sets of dentinal tubule lines visible in the cross-section of a tusk. Values below 90 degrees indicate African elephant ivory; values above 115 degrees indicate Asian elephant; mammoth ivory falls in an intermediate zone with a distinct pattern.
- What it is
- The acute angle formed where Schreger lines intersect in a tusk cross-section
- African elephant
- Below 90 degrees
- Asian elephant
- Above 115 degrees
- Mammoth ivory
- Intermediate zone with distinct pattern
Common questions
How do you measure the Schreger angle?+
You measure the acute angle where two sets of Schreger lines cross in a cross-section of a tusk. The lines are visible as arc patterns in the dentinal tubules. Multiple measurements are taken at different radii (distances from the center) and averaged together to get a reliable result.
What does the Schreger angle tell you?+
It helps you identify what species a tusk came from. Different animals have different angle ranges. African elephant ivory shows angles below 90 degrees. Asian elephant ivory falls around 115 degrees or higher. Mammoth ivory sits in an intermediate zone with its own distinct pattern.
Why can't you rely on a single Schreger angle measurement?+
A single measurement can be misleading. That is why forensic examiners take multiple measurements across the tusk at different depths and average them together. This gives you a more reliable species identification than one spot reading.
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Explained in these topics
- Ivory, Horn, and Tusk ExaminationThe acute angle measured where Schreger line arcs cross in a tusk cross-section. Below 115 degrees indicates Elephantidae (elephant); above 115 degrees indicat...
- Elephant Ivory ForensicsThe acute angle formed at the intersection of two sets of dentinal tubule lines visible in the cross-section of a tusk. Values below 90 degrees indicate Africa...