Yutyrannus: The Feathered Tyrannosaurus

• Name: Yutyrannus (Mandarin/Greek for "feathered tyrant"); pronounced YOU-tih-RAN-us
• Habitat: Woodlands of Asia
• Historical Period: Early Cretaceous (130 million years ago)
• Size and Weight: About 30 feet long and 1-2 tons
• Diet: Meat
• Distinguishing Characteristics: Large size; short arms; bipedal posture; long, downy feathers

About Yutyrannus

For the past couple of decades, paleontologists have been speculating about whether or not large tyrannosaurs like Tyrannosaurus Rex and Albertosaurus sported feathers—if not as adults, then perhaps at some stage during their hatchlinghood, youth, or adolescence. Now, the recent discovery in China of the largest feathered tyrannosaur yet identified, Yutyrannus, is sure to rekindle the debate about whether T. Rex and its ilk were green, scaly and reptilian (as they're usually depicted in the movies) or soft and downy, like giant baby ducks.

The early Cretaceous Yutyrannus, which weighed in the neighborhood of one or two tons, isn't the first feathered tyrannosaur ever identified; that honor belongs to the much smaller Dilong, a 25-pound Yutyrannus contemporary that was only about the size of a large turkey. It's also important to keep in mind that we have reams of fossil evidence for feathered theropods (meat-eating dinosaurs) that don't happen to be tyrannosaurs, some of which attained equally respectable sizes, if not quite in Yutyrannus' weight class. (One contender would be the truly enormous, and appropriately named, Gigantoraptor).

The important question now confronting paleontologists is, why did tyrannosaurs like Yutyrannus evolve feathers in the first place? Flight was out of the question for a 2,000-pound theropod, so the most likely explanation involves some combination of sexual selection (perhaps brightly feathered Yutyrannus males were more attractive to females) and insulation (feathers, like hair, help to regulate the metabolism of warm-blooded vertebrates, which theropods almost certainly were).