Size and Weight:
Its full name, Balaur bondoc, makes it sound like the supervillain from a James Bond movie, but if anything this dinosaur was even more interesting: an island-dwelling, late Cretaceous raptor with a host of weird anatomical features. First, unlike other raptors, Balaur sported two oversized, curved claws on each of its hind feet, rather than one; and second, this predator cut an unusually squat, muscular profile, very unlike its lithe, speedy cousins like Velociraptor and Deinonychus. In fact, Balaur possessed such a low center of gravity that it may have been capable of tackling much larger dinosaurs (especially if it hunted in packs).
Why did Balaur occupy a place so far outside the raptor norm? Well, it seems that this dinosaur was restricted to an island environment, which can produce some strange evolutionary results--witness the "dwarf" titanosaur Magyarosaurus, which only weighed a ton or so, and the comparably shrimpy duck-billed dinosaur Telmatosaurus. Clearly, Balour's anatomical traits were an adaptation to the flora and fauna of its island habitat, and evolved in their strange direction over millions of years of isolation.