This is Gigantoraptor erlianensis, a newly described oviraptorosaur from late Cretaceous of China. It’s a kind of nightmare version of Big Bird — it’s estimated to have weighed about 1400kg (1½ tons for non-metric Americans).
Histological examination of the growth structure of the bones suggests that this fellow was a young adult, about 11 years old, and that they grew rapidly and reached nearly this size by the time they were 7. And since it is a young adult, there were probably bigger gigantoraptors running around. They also compared limb length to other dinosaurs, like the tyrannosaurs—gigantoraptor had longer, slimmer legs and was more of a runner than they were.
There’s no sign whether it was covered with bright yellow feathers.
Xu X, Tan Q, Wang J, Zhao X, Tan L (2007) A gigantic bird-like dinosaur from the Late Cretaceous of China. Nature advance online publication, 13 June 2007.