First Dinosaur Brain Tumor Found, Experts Suggest

John Pickrell
for National Geographic News
November 24, 2003

Cancer isn't just an affliction of the modern world, new research suggests. Scientists behind the preparation of a fossil belonging to a new Tyrannosaurus rex relative believe they may have discovered the first known fossilized brain tumor.

Tumors are rare, even in living animals. But as a soft tissue, the average tumor's chance of making it to the fossil stage is even slimmer, said researchers behind the find, making the discovery highly unusual.

The golf-ball-sized brain tumor appears as a spongy mass inside the skull cavity of a 72-million-year-old Gorgosaurus fossil, now on display at The Children's Museum of Indianapolis in Indiana. The probable tumor would have affected the animal's balance and caused other damage, explaining the many crippling wounds and fractures recorded in her skeleton.

"This is the most damage I've ever seen in a skeleton where the animal survived," said paleontologist Peter Larson of the Black Hills Institute for Geological Research in Hill City, South Dakota. "We were amazed by just how many pathologies, or healed injuries, this animal has," he said.

Slender Cousin

Larson and Children's Museum curator of natural history, Dallas Evans, announced the find at last month's Society of Vertebrate Paleontology conference in Mineapolis/St Paul.

Amateur fossil hunters Cliff and Sandy Linster first discovered the female meat-eater, near Choteau, Montana, in 1997. The specimen, dated to the late Cretaceous Period, was found among the remains of hundreds of fossilized Maiasaura, a type of herd-living, duck-billed dinosaur.

Species in the genus Gorgosaurus were T-rex's slightly smaller, longer-limbed, and more slender cousins. They still packed a hefty punch, however: The average specimen was 25 feet (7.6 meters) in length, weighed a ton (0.9 metric ton) or more, and was equipped with over 60 four-to-five-inch-long (ten-to-thirteen-centimeter-long) serrated teeth. Just 20 Gorgosaurus specimens have ever been found, all in North America. This specimen—a previously unknown species—is one of the most complete.

Black Hills Institute researchers were first alerted to the unusual features of this fossil when they set about preparing and cleaning it for the Children's Museum. Alongside multiple healed fractures, Larson and colleagues first noticed an unusual rounded mass in the fossil's cranial cavity earlier this summer. "We found a weird mass of black material in the braincase," said Larson. "It was very bizarre. I'd never seen anything like it."

Bad Balance

Totally stumped as to what that mass might be, Larson and colleagues requested the assistance of veterinary pathologists from the pharmaceutical giant Eli Lilly and Company, a Children's Museum funder also based in Indianapolis.

Further probing with x-rays and an electron microscope revealed that the mass was originally formed from bony material, said Rachel Reams of Eli Lilly, but it didn't appear to be attached to the Gorgosaurus's skull. Ruling out the possibility that the mass was formed from skull fragments that fell into the brain cavity, the team decided that it was probably an extraskeletal osteosarcoma—a type of bone-producing tumor that can form in soft tissues.

Continued on Next Page >>


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