Forty-three years ago in east Africa, a team of scientists unearthed fossilized skeletal remains that rewrote the history of humanity. “Lucy,” an extinct primate of the family Hominidae (which includes humans), walked upright 3.2 million years ago and was believed to be our oldest found human ancestor. Last year, however, paleontologists in Germany discovered fossilized teeth, three times older than Lucy, that might once again rewrite our understanding of human evolution.

The dental remains were found during a research excavation near the town of Eppelsheim, in a former bed of the the Rhine river. The region has been a popular location for fossil hunters ever since a fossilized femur found in the 1820s launched the fields of paleontology and paleoanthropology. Deutsche Welle reports that although the 9.7 million-year-old teeth do not match any other known species found in Europe or Asia, they do resemble those belonging to Lucy. This baffled the research team so much that they delayed publishing their research for a year.