Paleontologist Thomas Carr, a leading expert on Tyrannosaurus rex, is visiting the Burke Museum from Carthage College in Wisconsin to take a closer look at Tufts-Love Rex. It’s the last day of his week-long visit to Seattle and he is quietly crouching below the massive T. rex skull using a headlamp to illuminate the details of its anatomy.
Carr is wrapping up a week of looking at approximately 2,000 features on the 66.3-million-year-old fossil to describe whether they show juvenile or adult condition.
Juvenile T. rex bones start out with a smooth surface and then become more roughened and textured as the animal ages. Documenting these growth changes will help to shed light on how this animal grew and matured along with ultimately answering some big evolutionary questions.
"Growth is a window into evolution,” said Carr. “No one has ever sat down to decode the full growth code of T. rex, most focus on only one aspect or set of features."
He believes that the Tufts-Love Rex was a young adult and at least 19 years old when it died. “There is a crest at the top of the skull that is absent in baby T. rex and the Tufts-Love Rex has the start of this crest,” said Carr. This age prediction can be tested by taking a histological section of a bone, such as a belly rib since leg bones are not preserved in the specimen, and counting the annual growth lines to obtain its chronological age.
"The Tufts-Love T. rex is a very important transitional specimen that helps fill in gaps between juveniles and adults. It's remarkably complete and shows excellent preservation.”
The phrases “remarkably complete” and “excellent preservation” don’t get used that often when it comes to dinosaur fossils. Conditions have to be just right to preserve the animal in the first place then its remains have to withstand millions of years of geologic forces.
Thankfully all bones are accounted for in the skull, even a thin and delicate bone called the epipterygoid that is not often preserved in fossils, making it one of the best-preserved T. rex skulls in the world.