Experts Say That Nanotyrannus is a Different Species from Small Tyrannosaurus

The first Nanotyrannus skull was discovered in Montana in 1942, but for decades, paleontologists have debated whether it is a separate species or just a much larger juvenile T. rex. In this new study, paleontologists from the University of Bath, Nick Longrich, and paleontologists from the University of Chicago, Evan Saitta, reanalyzed the fossils, examining growth rings, Nanotyrannus anatomy, and an previously unidentified juvenile T. rex fossil.

Measure the bone of Nanotyrannus.

By measuring growth rings on Nanotyrannus bones, they showed that these rings become increasingly dense towards the outer part of the bone - indicating slower growth. This suggests that these animals were nearing their full size; not fast-growing juveniles.

"Results Show"

The translation of the given text from 'Bahasa' to 'English' while preserving the HTML tags is as follows: Model of fossil growth shows that these animals reach a maximum size of about 900-1,500 kg and 5 m - approximately 15% of the size of the giant T. rex, which grows to 8,000 kg and 9 m or more.

"Ketika saya melihat hasil ini, saya sangat terkejut. Saya tidak menyangka hasilnya akan begitu meyakinkan," kata Dr. Longrich. Translation: "When I saw these results, I was very surprised. I didn't expect the results to be so convincing," said Dr. Longrich.
"Jika mereka masih muda T. rex mereka seharusnya tumbuh dengan gila-gilaan, menambah berat badan ratusan kilogram per tahun, tapi kami tidak melihat hal itu." Translation: "If they were still young T. rex, they should have grown tremendously, gaining hundreds of kilograms per year, but we didn't see that."

Source: Sci.news

"When I saw these results, I was very surprised. I didn't expect the results to be so convincing," said Dr. Longrich.

"\u201cIf they were still young, T. rex should have grown like crazy, gaining hundreds of kilograms of weight per year, but we didn't see that.\u201d"

"Kami mencoba memodelkan data dengan berbagai cara dan tetap mendapatkan tingkat pertumbuhan yang rendah. Ini sepertinya akhir dari hipotesis bahwa hewan-hewan ini adalah T. rex muda." Translation: "We have tried to model the data in various ways and still obtained a low growth rate. This seems to be the end of the hypothesis that these animals are young T. rex."

add Dr. Longrich.

"If you see another young tyrannosaurus, they show many characteristics of adult tyrannosaurs. Tarbosaurus, which is still very young, a close relative of T. rex, shows the characteristics of adult tyrannosaurs," said Dr. Longrich."

"Like kittens look like cats and puppies look like dogs, different baby tyrannosaurs also look different. And Nanotyrannus doesn't look like T. rex at all." "It may have grown in a very different way from other tyrannosaurs, or other dinosaurs – but most likely it is not a T. rex."

However, this raises a mystery if Nanotyrannus is not a teenage Tyrannosaurus, why has no one ever found a young T. rex?

"It has always been one of the big questions. Turns out we really found it," said Dr. Longrich.

"Collected for Years"

"But the fossil was collected years ago, left in an unidentified bone box in the museum drawer, and then forgotten."

Nanotyrannus is lighter and longer in body compared to T-rex. It also has larger arms, unlike the famous short arms of T. rex.

"The arms are actually longer than those of T. rex. Even the largest T. rex had shorter arms and smaller claws compared to this small Nanotyrannus. This is an animal where its arms are actually quite strong. It truly is just a completely different animal - small, fast, agile," said Dr. Longrich.

"T. rex relies on size and strength, but this animal relies on speed."
"Long arms and other features indicate that this is only distantly related to T. rex - and may be outside the Tyrannosauridae family, which is part of T. rex, in its own family of predatory dinosaurs."

A paper about this discovery was published in the Fossil Studies journal.

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