There is new evidence that the Tyrannosaurus Rex grouped with birds than with reptiles:
"We determined that T. rex, in fact, grouped with birds — ostrich and chicken — better than any other organism that we studied," said researcher John Asara of Beth Israel Deaconess Medical Center and Harvard Medical School. "We also show that it groups better with birds than [with] modern reptiles, such as alligators and green anole lizards."
This came about with the finding of a drumstick with soft tissue still intact inside. Neat.