400-Million-Year-Old Insects Ate Dirt, British Experts Say : SCIENCE FILE: An exploration of issues and trends affecting science, medicine and the environment.

British scientists have discovered the remains of some of the animal world’s first meals and found that primitive creatures probably ate dirt. Sorting through 400-million-year-old deposits, researchers from the University of Wales found tiny pellets of feces from unknown insects that provide some of the earliest evidence yet of animals eating either plants or the remains of plants, predating other similar evidence by 90 million years.

“The assumption that one had a very simple food chain of animals eating plants and then animals eating other animals does not have any evidence in the fossil records,” paleobotanist Dianne Edwards said in the journal Nature. She said the first land animals--creatures similar to today’s centipedes and millipedes--first ate plant detritus--dirt--and then each other.