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Scientists have stated that fossils previously believed to be from adolescent Tyrannosaurus rexes actually belong to fully grown individuals of a different predatory dinosaur species that was more agile.
According to a study published in the journal Fossil Studies, a recent analysis of the specimens indicates that the creatures that inhabited the Earth 66 million years ago were not rapidly developing young, but rather close to their full size.
For many years, there has been a lot of disagreement over these fossils ever since the first complete skull was discovered in Montana, USA, in 1942.
There has been debate about whether the specimens are of the species Nanotyrannus lancensis, which is a smaller and more streamlined relative of the T. rex, or if they are young T. rexes rather than fully grown adults.
Nick Longrich, a researcher at the Milner Centre for Evolution at the University of Bath, expressed surprise at the findings of their study. The research involved examining the growth rings in bones and creating models to understand how the animals grew.
He remarked, “I was not anticipating such a conclusive outcome.”
It is expected that young T. rex would experience rapid growth, gaining hundreds of kilograms annually. However, this does not seem to be the case.
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We attempted various methods of modeling the data, but consistently obtained low growth rates.
The hypothesis that these animals are young T. rex appears to be reaching its conclusion.
According to the study, the dinosaurs in question would have reached a maximum weight of 900 to 1,500 kilograms and a length of five meters, which is approximately 15% of the size of a full-grown T. rex. The adult T. rex was estimated to weigh around 8,000 kilograms and measure almost nine meters long.
The team also stated that the growth patterns observed in the fossils do not suggest that they belonged to juvenile T. rex specimens.
According to Dr Longrich, the young of various tyrannosaur species have distinct appearances, much like how kittens resemble cats and puppies resemble dogs.
Nanotyrannus does not bear any resemblance to a T. rex.
The scientists also examined these ancient remains alongside another sample that was recently determined to be a young T. rex.
According to Dr. Longrich, this particular specimen possesses unique characteristics that are not typically found in Nanotyrannus.
If these were juvenile T. rex, they would be experiencing rapid growth and gaining hundreds of kilograms each year. However, that is not what we are observing.
Based on the team’s research, it appears that Nanotyrannus had a slender build and longer limbs compared to the robust T. rex, and also possessed bigger arms.
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Dr. Longrich stated that the arms of T. rex are shorter than those of the specimen in question.
“The largest T. rex, despite its size, possesses arms and claws that are shorter and smaller compared to those of the tiny Nanotyrannus.”
This creature possessed arms that were highly effective as weapons.
“It’s essentially a completely distinct creature – petite, swift, and nimble.”
The Tyrannosaurus rex depended on its immense size and strength, while this creature relied on its quickness.
According to researchers, the Nanotyrannus is only distantly related to the T. rex, based on comparisons.
He stated, “Nanotyrannus is a topic of great controversy in the field of paleontology.”
Recently, it appeared that we had resolved this issue when a juvenile T. rex was involved.
“I was initially doubtful about Nanotyrannus until approximately six years ago, when I examined the fossils closely and was astonished to discover that we had been mistaken all this time.”
Source: independent.co.uk
