Since the discovery of a 2-meter-tall (7-foot-tall) meat-eating dinosaur in 1942, scientists have debated whether it existed on Earth 66 million years ago. Some scientists believe the Nanotyrannus – whose name means “tiny tyrant” – is a different species from T. rex altogether. Others think it is simply a smaller, younger version of the T. rex.
Now, paleontologists with the University of Kansas think they may have unearthed the answer.
Last summer, researchers returned to a dinosaur site first uncovered two years ago in Montana’s Hell Creek Formation. Along with a complete upper jaw section containing all of the animal’s teeth, researchers were able to successfully excavate “bits” of its skull, foot, hips, and backbones.
But whether it is a juvenile T. rex or an example of the contentious Nanotyrannus remains to be determined.
“We plan to make that analysis in our scientific work to come,” researcher David Burnham told IFLScience.
In 2003, a nearly complete fossil dubbed “Jane” was discovered and measured at 6 meters (20 feet) long and 2 meters (7 feet) tall. If this new specimen and Jane belong to the same species, it means a “pygmy” relative of the 13-meter-long (42-foot-long) T. rex could have been roaming North America during the Cretaceous period.
But Burnham isn't convinced. He says that dinosaurs – like birds of today – were morphologically different than their parents but still belonged to the same species.
Little is known about the young T. rex's life cycle. According to Smithsonian Magazine, less than five juveniles have come from this excavation site in the last century. Burnham’s team hopes this find will change that.
“Since we now have more complete material to work with, we may be able to say something about the ecology and habits of the juveniles,” he said. “We have some hints that suggest they had different hindlimb proportions and being much smaller they may have had a different ecology. The hindlimbs suggest they were fast runners and their smaller size indicates they probably did not go after large prey.”
The crew will now work to compare the skull to other specimens, as well as analyze teeth and bones to determine the animal’s age more precisely. While their work is not yet published in a journal, Burnham says his crew is working on a paper and plans to return to the site this summer for further excavation.