Size and Weight:
The large theropod dinosaur Mapusaurus was discovered all at once, and in a big heap--an excavation in South America in 1995 yielded hundreds of jumbled bones, which required years to sort out and analyze. It wasn't until 2006 that researchers announced the "diagnosis" of Mapusaurus, which was closely related to the even bigger Giganotosaurus and must have been one of the most feared hunters of its day.
Interestingly, the fact that so many Mapusaurus bones were found jumbled together can be taken as evidence of herd, or pack, behavior--raising the possibility that this dinosaur hunted cooperatively in order to take down the huge titanosaurs populating middle Cretaceous South America. On the other hand, a flash flood could also have resulted in the accumulation of unrelated Mapusaurus bones, so the pack-hunting hypothesis should be taken with a big grain of prehistoric salt.