Tyrannosaurus rex and its cousins lived until around 65 million years ago and earlier relatives are thought to have been much smaller than the T-Rex we have come to know, but this notion has been challenged by the discovery of three specimens of a new species of tyrannosauroid from the Lower Cretaceous, 125 million years ago. The dinosaur, Yutyrannus huali, whose name translates from Latin and Mandarin as ‘beautiful feathered tyrant’, shares some features with derived tyrannosaurs, but has three-fingered forelimbs and a typical theropod foot, like other early tyrannosaur relatives.
Smaller dinosaurs with primitive feathers have been discovered before, but this is the first direct sign of a huge dinosaur that is...shaggy.
It seems T-Rex had a softer, gentler side. Or at least it might look that way to us unless we saw it up close. It was 30 feet long and weighed in at 1,400 kilograms, previously unknown sizes for basal tyrannosauroids of the Lower Cretaceous. The two juveniles also discovered may have tipped the scales at a half-ton.
Artist’s impression of a group of Yutyrannus huali and two individuals of the smaller Beipiaosaurus. Credit: Dr Brian Choo
It certainly looks a lot like derived tyrannosauroids - the skull is large and deep, for example. What about those feathers, though? Well, evolution is fickle. Most large mammals became almost entirely hairless because low surface-to-volume ratios allowed them to retain metabolic heat but Y. huali lived during a period colder than the rest of the Cretaceous - later tyrannosauroids lived in a much warmer climate.
Fuzzy, even cuddly. Maybe Tyrannosaurus needs a new marketing campaign.
Citation: Xing Xu, Kebai Wang, Ke Zhang, Qingyu Ma, Lida Xing, Corwin Sullivan, Dongyu Hu, Shuqing Cheng &Shuo Wang, 'A gigantic feathered dinosaur from the Lower Cretaceous of China', Nature, doi:10.1038/nature10906