New analysis of fossils believed to be young T. rex, now shows they were adults of a small tyrannosaurus with a narrower jaw, longer legs and larger arms T. rex. Type, Nanotyrannus lancensis was first named decades ago. but was later reimagined as younger T. rex.

first skull nanotyranus It was found in Montana in 1942, but paleontologists debated for decades whether it was a separate species or the offspring of a much larger species. T. rex.

Expert analysis of fossils

Dr. from the Milner Center for Evolution, Department of Life Sciences, University of Bath (England). Nick Longrich and Dr. from the University of Chicago (USA). Evan Saitta reanalyzed the fossils by looking at growth rings. , anatomy nanotyranus and a previously unknown juvenile fossil T. rex.

By measuring growth rings in bones nanotyranusThey showed that as they approached the outer side of the bone, its growth slowed down. This shows that these animals were almost full size; He is not a fast-growing teenager.

Fossil growth modeling showed that the animals reached approximately 900-1,500 kilograms (~2,000-3,300 pounds) and five meters (~16 feet) tall; this was about 15 percent the size of the giant T. rex, which reached 8,000 kilograms (~18,000 pounds) and nine meters (~30 feet) or more.

The researchers published their findings in a journal Fossil Studies.

“I was very impressed when I saw these results,” Longrich said. “I didn’t expect it to be this convincing. “If they were young T.Reksami, Then they should be growing like crazy, gaining hundreds of kilos a year, but we can’t see that. “We tried modeling the data in many different ways and kept getting low growth rates. This seems to be the end of the hypothesis that these animals are young T. reksami“.

Distinguishing features of Nanotyrannus

While the researchers confirmed the existence of different species, they found no evidence of fossils that combined features of Nanotyrannus. And T. rex – that will exist when one transforms into the other. Every fossil they examined could be identified with certainty as one species or another.