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T-Rex Cousin Had Feathers

Yutyrannus illustration by Brian Choo

She weighed a ton and a half, was at least 30 feet long, lived about 125 million years ago, and was an early cousin of the Tyrannosaurus family. But the really big thing about her is that she had soft, fuzzy feathers.

Meet Yutyrannus, the largest feathered dinosaur ever discovered.

We’ve known for some time that many dinosaurs had feathers, and that today’s birds are their descendants. (The dinos never went extinct; the ones who survived the big event 65 million years ago just evolved into birds.) But Yutyrannus is 40 times heavier than the biggest feathered dinosaur ever found before now.

Does that mean the even huger, fearsome T-Rex, about five times bigger than Yutyrannus, was also a cute, downy monster? Quite possibly, says Xing Xu, China’s most renowned dinosaur hunter, who discovered Yutyrannus and has been researching feathered dinosaurs for many years.

Dr. Xu’s study, published in the journal Nature, says that Yutyrannus’s feathers were not the kind that could have been used for flying purposes. They were more of the downy type, like what you see on an emu.

Dr. Xu’s team found three fossilized remains of Yutyrannus: an adult and two children. (See photo right for the head of the adult.) The fossilized feathers, about six inches long, were preserved in patches on different parts of the three fossils, which is why the scientists believe that Yutyrannus’s entire body was probably covered in feathers.

Until now, and since the largest feathered dinosaurs ever found were much smaller than Yutyrannus, it was thought that their down was mostly to keep them warm. Because of their size, the larger dinosaurs didn’t need down or fur, so the assumption was that the larger species wouldn’t have needed feathers. But they could still have used them for their attractiveness – i.e. to woo their lady friends – just as colorful birds do today.

However Yutyrannus used her feathers, she stands all earlier assumptions on their head and raises the possibility that even T-Rex would have looked quite cute … at least until she swallowed you.