The phrase "petrous bone" refers to a part of our skull. It is a hard and dense bone located on each side of our head, near our ears. It helps protect important structures like the inner ear and some blood vessels. Full definition
The new samples include, to our knowledge, the first genome - wide ancient DNA from Anatolian Neolithic farmers, whose genetic material we obtained by extracting from petrous bones, and who we show were members of the population that was the source of Europe's first farmers. (nature.com)
Optimal ancient DNA yields from the inner ear part of the human petrous bone. (nature.com)
The authors specifically asked their colleagues to make available the inner ear petrous bones because they're especially rich in prehistoric genetic material. (science.howstuffworks.com)