Mineral dust ingested with food causes distinct signs of wear on the teeth of plant-eating vertebrates, which can differ considerably depending on the type of dust. This is what paleontologists at Johannes Gutenberg University Mainz (JGU) have discovered in a controlled feeding study of guinea pigs. As they report in the current issue of Proceedings of the National Academy of Sciences of the United States of America (PNAS), their findings could lead to a more accurate reconstruction of the eating habits of extinct animals as well as a reconstruction of their habitats.