Palaeontology

Some juvenile T. rex fossils are a distinct species of small dinosaur

By T.K. Randall
January 3, 2024 ·  0 comments

Image Credit: CC BY-SA 3.0 ScottRobertAnselmo Tyrannosaurus rex certainly needs no introduction - this gargantuan carnivorous reptile is widely considered to be one of the fiercest land predators ever to walk the face of the Earth.

With adults measuring up to 43ft in length, 15ft in height and weighing in at as much as 9 tons, there would have been few spectacles as terrifying as a fully grown adult T.rex charging toward you.

Over the years, palaeontologists have unearthed a number of fossil T. rex specimens of various sizes with the smaller examples typically being thought to be juveniles.

Now, though, a fossil belonging to what was thought to be a young T. rex that had originally been discovered all the way back in 1942 has been reclassified as a separate species altogether.

At the time it was first found, the fossil was assumed to be a new species and named Nanotyrannus lancensis, but in the years that followed most experts agreed that it was actually a juvenile T. rex.When Dr. Nick Longrich of the University of Bath and Dr. Evan Saitta of the University of Chicago recently decided to reanalyze the fossil, however, they quickly cast this idea back into doubt.

By measuring the growth rings and the anatomy of the fossil, it turned out that this particular species only reached around 15% of the size of a T. rex even when fully grown.

"When I saw these results I was pretty blown away," said Longrich.

"I didn't expect it to be quite so conclusive. 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."

"We tried modeling the data in a lot of different ways and we kept getting low growth rates. This is looking like the end for the hypothesis that these animals are young T. rex."

Source: Phys.org | Comments (0)

Tags: Tyrannosaurus, Dinosaur