Tumor found in a 255-million-year-old mammalian ancestor

A tumor in a 255-million-year-old mammalian ancestor called a gorgonopsian is detailed in a new research letter published online by JAMA Oncology.

The research letter by Megan R. Whitney, M.Sc., of the University of Washington, Seattle, and coauthors reports on a microscopic study of part of a gorgonopsian's jaw, which included examining wafer-thin slices of the specimen.

Ectopic toothlike structures that resembled miniature teeth were seen, an ancient condition that the authors suggest resembles compound odontoma, which is a common type of tumor although what causes it is not well understood. In humans, compound odontoma is characterized by miniature teeth that can cause the resorption of the functional tooth.

Odontomas were previously unknown in deep premammalian evolutionary history, according to the article.

"Recognition of odontoma in such a distant relative of humans suggests that this condition is unlikely related to characteristics of mammalian dentition [teeth] or physiologic features but rather evolved much earlier in vertebrate evolution," the report conclude.