Tiny Tyrant—Fossil May Be Mini T. Rex Cousin

By Bijal P. Trivedi
National Geographic Today
August 9, 2002

Paleontologists from a small museum in Rockford, Illinois, have found what they believe to be the skeleton of the tiny tyrant Nanotyrannus—a smaller, faster but equally ferocious meat-eating relative of Tyrannosaurus rex.

The only known evidence of this dinosaur is a single specimen, a skull, which resides in the Cleveland Museum of Natural History. But the Cleveland skull has been the focus of controversy; some believe it is Nanotyrannus, a new genus of dinosaur, while others claim it is a juvenile T. rex, which has never been found.

"I'm 100 percent sure that what we have here is Nanotyrannus," said Michael Henderson, curator of Earth Science at the Burpee Museum of Natural History in Rockford. "When we saw the teeth we knew exactly what we had."

Based on the skull and a collection of teeth gathered from Montana, South Dakota, and Wyoming, Henderson and his colleagues believe that the teeth of Nanotyrannus are slim and razor-like for slicing through flesh. T. rex, by contrast, has teeth like railroad spikes—larger and rounder for piercing and puncturing prey and biting through bones.

Furthermore, the new specimen is definitely not a juvenile, said Henderson, who led the expedition into the southeastern corner of Montana where the dinosaur was discovered. "It has a couple of fused vertebrae and the three pelvic bones are fused into one bone, which would only occur in an adult," he said.

The specimen, named "Jane" for a major donor to the Burpee Museum, is thought to have lived sometime between 68 and 65 million years ago—just before the mass extinction that wiped out the dinosaurs. She looks about 22 feet long and her long, narrow shin and anklebones suggest that she was "the cheetah of the Cretaceous," said Robert Bakker, who first described Nanotyrannus in 1988 together with co-authors Phil Currie and Mike Williams.

Discovery by Amateurs

Jane was actually discovered in June 2001 by volunteer dinosaur hunters Bill Harrison and Carol Tuck while on a prospecting expedition led by Henderson in Montana's Badlands.

They discovered a six-inch-long toe jutting out of the base of a 20-foot (6-meter) cliff face. From here they noticed a cross section of a lower limb, and lower down, a foot and pelvis, which implied that there was a significant portion of the skeleton within the cliff.

Henderson marked the site, removed the toe and foot bone, and returned nearly one year later in May 2002 with permits, shovels, and volunteers.

"Until about two weeks ago we had no idea what we had found," said Joe Peterson, a junior at Southern Illinois University at Carbondale and an assistant to Henderson. A broken bone with a hollow space inside indicated that the creature was a carnivore, but yielded few other clues. When the toe was compared to specimens at the Black Hills Museum of Natural History in Hill City, South Dakota, last year, the team suspected that they had found Struthiomimus, an ostrich-like carnivorous dinosaur from the late Cretaceous period that was a tremendously fast runner.

Continued on Next Page >>


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