A comparison of trephination techniques

"This skull shows four different instruments used for trephination. The instruments include a shark’s tooth, a flint-pointed bow drill, a flint scraper and obsidian – a naturally occurring volcanic glass. Each instrument makes a different type and size of hole. This skull was owned by Dr Thomas Wilson Parry (1866-1945), an English doctor who did extensive practical research into Neolithic trephination instruments and techniques."

Text and images from Science Museum (U.K.), via Sutured Infection.