T-Rex sized, in fact:

Researchers in China have unearthed the bones of a gigantic bird-like dinosaur, dwarfing anything else in its category.

Alive, the beast is thought to have been 8 metres long, 3.5 metres high at the hip and 1,400 kilograms in weight — 35 times as heavy as its next largest family members and 300 times the size of smaller ones such as Caudiperyx. It has been classified as a new species and genus: Gigantoraptor erlianensis.

The evolution of bird-like features had long been thought to be accompanied by a decrease in size, meaning the smaller the species, the more bird-like it is likely to be and vice versa. The new discovery shows that isn't necessarily true.

Gigantoraptor had long arms, bird-like legs, a toothless jaw, and probably a beak. There are no clear signs as to whether it was feathered. However, judging from its close affinity to other dinosaurs known to have been feathered, Xing Xu of the Institute of Vertebrate Paleontology and Paleoanthropology in Beijing speculates that it was.

I'm guessing this bad boy didn't fly. And maybe that's just as well...