A benign tumor, compound odontoma, found in humans and other mammals manifesting as little outgrowths in the gums must have ached a gorgonopsid some 255 million years ago.

Odontoma is a painful condition and is often cured with a surgical intervention.

This was confirmed by researchers of the University of Washington after a discovery of the said tumor in the fossilized jaw of gorgonopsian.

The details have been published in the Journal of the American Medical Association Oncology.

This is the first time that tumor has been confirmed with such an old fossil, as it used to be restricted to ice age fossils.

"We think this is, by far, the oldest known instance of a compound odontoma," said Christian Sidor, senior author and professor of biology at the University of Washington.

He said the discovery indicates that it was an ancient type of tumor.

Fossil From Tanzania

The gorgonopsian jaw came to Sidor in 2007 from Tanzania's Ruhuhu Valley. However, he was unaware of the tumor factor that time.

Later on, the investigation by Megan Whitney, lead author and biology graduate student, on the tooth structure of gorgonopsians finally led to the trail of the big discovery. 

The author wanted to examine the denture styles of mammals and reptiles and noted that reptiles usually fuse teeth into the jawbone, unlike mammals, which use hard string-like tissues to hold teeth in sockets. Whitney wanted to check if the same was true for gorgonopsians.

Detailed Investigation

During the study, Whitney insisted slicing of fossilized gorgonopsian jaw for examining very thinner sections under a microscope to study the binding pattern of the teeth with the socket. However, fearing damage to the fossil, Whitney and Larry Mose, a UW undergraduate student working with Whitney, picked up a solitary gorgonopsian lower jaw for a detailed examination.

After mounting many thin slices onto slides, they noticed a variation in terms of eight round objects seen embedded to the root of the canine.

Under microscopic magnification, Whitney found the objects within each cluster as poorly differentiated and carrying clear layers of enamel and dentin.

After an investigation, it was confirmed that gorgonopsian had compound odontoma.

Commenting on the discovery, Judy Skog, program director in the National Science Foundation's Division of Earth Sciences, said the earliest known occurrence of this tumor was about 1 million years ago in fossils of mammals. That makes the new research very unique.

As top predators, gorgonopsians belong to a group of animals called synapsids. These mammal-like reptiles lived before mammals evolved.

According to Whitney, most synapsids are now extinct, and mammals are the only living descendants.

In the past too, researchers have found tumors in the fossils of ancient creatures including dinosaurs. Before this discovery, the earliest known evidence of odontomas was in Ice Age-era fossils.