Tyrannosaurus is one of the most intensively studied and best known dinosaurs. Nevertheless, their relationship and system are highly controversial. The ongoing discussion is Nanotyrannus lansensisinterpreted as either a separate genus of small-bodied tyrannosaurs, or a juvenile tyrannosaurus. tyrannosaurus rex. In a new study, paleontologists from the University of Bath and the University of Chicago examined multiple lines of evidence that Nanotyrannus lansensis as a separate species.
first skull Nanotyrannus It was discovered in Montana in 1942, but paleontologists have debated for decades whether it was a separate species or just a juvenile of a much larger species. tyrannosaurus.
In the new study, paleontologist Nick Longlich of the University of Bath and paleontologist Evan Saitta of the University of Chicago reanalyzed the fossil and looked at its growth rings and body structure. Nanotyrannusand hitherto unrecognized fossils of youth tyrannosaurus.
Measuring tree rings Nanotyrannus They found that the bone was more densely packed toward the outside, indicating that bone growth was slowing down. That suggests these animals were nearly life-sized. It is not a young body that grows quickly.
Fossil growth modeling shows that the animal could have weighed between 900 and 1,500 kg and reached a maximum length of 5 meters, about 15% of the size of a giant. . tyrannosaurus8,000 kg and grew to over 9 m.
“I was quite surprised when I saw these results. I didn't expect to see such conclusive results,” said Dr. Longlich.
“If they were young tyrannosaurus They're supposed to grow like crazy and gain hundreds of pounds a year, but we don't see it that way. ”
“We tried modeling the data in different ways, but still got low growth rates. This seems to put an end to the hypothesis that these animals are young.” tyrannosaurus”
Researchers found no fossil evidence that combined both traits to support the existence of different species Nanotyrannus and tyrannosaurus —If one turns into the other, it will exist.
Every fossil they examined could be confidently identified as one or the other species.
The growth patterns of other tyrannosaurs were also inconsistent with the hypothesis that these tyrannosaurs were young. tyrannosaurus.
“If you look at other juvenile tyrannosaurs, you'll see a lot of characteristics that are typical of adults. Very young. tarbosaurus — next of kin of tyrannosaurus — exhibiting unique characteristics of adults,” Dr. Longrich said.
“Just as kittens look like cats and puppies look like dogs, the various juvenile tyrannosaurs are also unique. And Nanotyrannus nothing similar tyrannosaurus”
“It may have grown in a completely different way than other tyrannosaurs or other dinosaurs, but it's more likely that it simply wasn't a dinosaur. tyrannosaurus”
But it poses a mystery. Nanotyrannus not a boy tyrannosaurusSo why didn't anyone find the young man? tyrannosaurus?
“That was always one of the big questions. Well, it turns out we actually found it,” Dr. Longrich said.
“However, this fossil was collected many years ago, put away in a box of unidentified bones in a museum drawer, and then forgotten.”
Nanotyrannus They were lighter in build and had longer limbs than their stouter relatives. It also had larger arms, unlike those known for their short arms. tyrannosaurus.
“Actually, my arms are longer than people's.” tyrannosaurus.Even the biggest one tyrannosaurushave shorter arms and smaller claws than these smaller animals. Nanotyrannus. This was an animal whose arms were actually pretty scary weapons. It's actually a completely different animal, smaller, faster and more agile,” Dr. Longrich said.
“tyrannosaurus While animals relied on size and strength, this animal relied on speed. ”
“The long arms and other features suggest it was only a distant relative.” tyrannosaurus — and may have been sitting outside the family TyrannosauridaeWhich tyrannosaurus Part of the predatory dinosaur family. ”
a paper The survey results were published in a magazine fossil research.
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Nicholas R. Longrich and Evan T. Saitta. 2024. Taxonomic status of Nanotyrannus lansensis (Dinosaur: Tyrannosauridae) – A different taxon of small tyrannosaurs. Phos.stud 2 (1): 1-65; doi: 10.3390/fossils2010001
Source: www.sci.news
