Fossils once thought to be teen Tyrannosaurus rex fossils may instead be a separate, smaller Tyrannosaurus species. When scientists reexamined the bones of the fossils, they found that the growth rings and simulated weights did not match those modeled for a T. rex, but instead were closer to a full grown Nanotyrannus lancensis.
The findings published in Fossil Studies showed that as the dinosaur's growth slowed, the rings found towards the outer edge of the bone were more closely packed together. This indicated that the dino's growth was slowing down and it was most likely full-grown. Young dinosaurs would still show rapid bursts of change in their bones at a young age.
"If they were young T. rex they should be growing like crazy, putting on hundreds of kilograms a year, but we're not seeing that," said Nick Longrich, a paleontologist at the University of Bath in the U.K., in a statement.
Do the Fossils Belong to a Young T. rex, or Not?
The new research challenges a different study from 2020 in Science Advances that suggests that the fiercely debated fossil status was not a separate species but a teenager T. rex close to starting a rapid shift in growth.
