Brief story at Discovery about Tyrannosaur finds at Hell Creek:
including a youthful scamp.
Interesting that the stripling is called B-rex (note the dash) and the elders T. rex.
Anyway, the main issue discussed is why they've been finding tyrannosaurs and little else:
"We don't know if we've been totally lucky or it's something else," said Horner. "We're totally puzzled." One Triceratops and a duckbill dinosaur were found the first year of the now three-year-old excavation site, he said. But since then the only dinos they've found have been T. rex.
Among the possible explanations is that T. rex just had better bones.
"Tyrannosaurs have very, very dense bones — so the chances of preserving are better," said [Phil] Currie.
Thicker than the bones of herbivores? I'm surprised.