Size and weight:
As is often the case in the dinosaur kingdom, the name Bicentenaria is a bit of a misnomer. The scattered remains of this small theropod were actually discovered in 1998, and revealed to the world in an article published in 2012; the 200th anniversary of the country of Argentina actually transpired in between, in 2010.
Bicentenaria is important for two reasons. First, this dinosaur was a coelurosaur, that is, a meat-eater closely related to Coelurus. The problem is, Coelurus dated from the late Jurassic period (about 150 million years ago), while the remains of Bicentenaria date to the middle to late Cretaceous (95 to 90 million years ago). Evidently, while other theropods went merrily about their evolutionary way, developing into plus-sized tyrannosaurs and vicious raptors, Bicentenaria remained stuck in a Mesozoic time warp. Considering the time and place in which it lived, Bicentenaria was a surprisingly "basal" dinosaur; if it weren't for the unmistakable sediments in which it was buried, paleontologists might be forgiven for believing that it lived 50 million years earlier than it actually did.
Second, the discovery of numerous associated Bicentenaria remains (this dinosaur was reconstituted from the bones of various individuals buried in an Argentinean reservoir) has led paleontologists to speculate that it hunted and/or traveled in packs. It's difficult to know how much weight to give to this theory, since it's not unknown for dinosaur carcasses from different time periods to wind up accumulated in the same location, thanks to floods and prevailing river currents.