In 2005, a Schweitzer et al. reported that they had found soft tissue in the marrow of a T. rex. bone. Examination of the tissue showed evidence of cell-like structures that could indicate preserved cells. Also stuff was squishy like protein. It if held up, an incredible discovery.
In 2007, Schweitzer et al. followed it up with more extensive analysis that indicated the presence of collagen I protein. Most exciting, they used mass spec to sequence a few fragments of dinosaur protein. It was quite similar to chicken collagen, and of course birds are the closest living relatives of dinosaurs.
Then in 2008, Kaye et al. analyzed a number of fossils and found similar traces, but interpreted them as bacterial colonies, as biofilm. They even saw the cell-like traces in a fossil ammonite, a creature without blood cells.
This year, Schweitzer et al. doubled down, publishing collagen I protein sequence from a hadrosaur.
In total the two papers found protein sequences that cover 169 aa of collagen protein sequence. Here are the overlapping dinosaur sequences with the gaps removed aligned to chicken sequence. The dinosaur sequences differ from the chicken sequence at five positions.
It will be interesting to see if these results hold up. I would like to see replication by a second lab. Most convincing would be two labs given the same unknown sample and both finding the same new collagen protein sequence.