Courtesy of Chistian Sidor/Megan Whitney/Handout via REUTERS

University of Washington researchers on Thursday described a benign tumor composed of miniature tooth-like structures they found embedded next to the root of the creature’s enlarged canine tooth while studying an unrelated aspect of the jaw. The animal was a member of an extinct group of four-legged carnivores called gorgonopsians that mixed mammal-like and reptile-like traits. When the researchers sliced into the mandible fossil from Tanzania's Ruhuhu Valley, they found a benign dental tumor called a compound odontoma that grows within the gums or other jaw soft tissues. The newest odontoma evidence was discovered in the 255 million-year-old lower jaw fossil of a gorgonopsid, a mammal predecessor. Back to top Article Information

Corresponding Author: Megan Whitney, MSc, Department of Biology, University of Washington, PO Box 351800, Seattle, WA 98195 (megwhit@uw.edu). Until now, this type of tumor was known only in mammals, including some Ice Age fossils tens of thousands of years old. Interestingly, odontomas have been reported in a handful of fossil mammals up to a few million years old4,5 but were previously unknown in deep premammalian evolutionary history. Scientists recalled the discovery in a new paper, published this week in the Journal of the American Medical Association Oncology.
University of Washington researchers report, in the peer-reviewed Journal of the American Medical Association Oncology, the discovery of an odontoma — a benign tumor — in the fossil of a 255-million-year old Tanzanian mammal-like saber-toothed gorgonopsia. This is one of the oldest-known tumors ever found.