Size and Weight:
Talk about a bum rap: when the first fossil of Oviraptor was unearthed, sitting atop a clutch of fossilized eggs, the eggs were thought to belong to an entirely different kind of dinosaur, Protoceratops (specimens of which had been found in the immediate vicinity). Naturally, it was assumed this new genus of dinosaur had stolen the eggs, hence the name that was bestowed on it by Henry Fairfield Osborn, Greek for "egg thief." (See 10 Facts About Oviraptor and a gallery of Oviraptor pictures.)
Although it's still saddled with its inaccurate name, Oviraptor has since been completely vindicated. Paleontologists now believe that the "guilty" specimen had actually been brooding a clutch of its own eggs, and earned its notoriety simply by being a good mother (or possibly a good father, since males of the species could conceivably have taken part in child-rearing, as is the case with modern birds).
Once you get beyond this little misunderstanding, Oviraptor was one of the most birdlike of all dinosaurs, with a sharp, toothless beak and (probably) a coat of feathers. This theropod didn't have wings, but it seems to have been a short step away (in evolutionary terms) from the first flying birds. (By the way, confusingly enough, Oviraptor doesn't technically count as a true raptor, the breed of dinosaurs most famously represented by Deinonychus and Velociraptor--but the family to which it belongs, the oviraptisaurs, includes a huge number of similarly feathered dinosaurs.)