'T rex' protein may have contained traces of ostrich rather than chicken

A fresh analysis of ancient protein from a fossilized Tyrannosaurus rex has revealed traces of ostrich haemoglobin in the original samples, which in an earlier study, were determined to have matched that of a chicken.
 
In the previous study, researchers identified seven fragments from a protein called collagen1, found in connective tissue, and said their sequences most closely matched the chicken version of the protein2.
 
The samples came from the fossilized femur of a T. Rex. As well as further strengthening the evidence for the link between dinosaurs and birds, the findings would make the protein the oldest ever to be sequenced - by around 68 million years.
 
Now, according to a report in Nature News, Martin McIntosh, a mass spectrometrist at the University of Washington in Seattle, has claimed to have identified ostrich haemoglobin protein in a cache of 48,000 protein spectra.
 
McIntosh suspects the samples were somehow contaminated with proteins from modern species.
 
McIntosh's findings came to light on February 23 at the sixth annual meeting of USHUPO - part of the international Human Proteome Organisation - in San Diego, California.
 
In the course of a lecture, Pavel Pevzner, a computational biologist at the University of California, San Diego, cited McIntosh's work and called for an independent review of the original results.
 
He said that his analysis provides statistical support for two of seven collagen proteins the Science authors said were from T. rex.
 
But now, the contamination issue has raised new concerns about the validity of the earlier findings.
 
McIntosh also wrote a technical comment for Science, suggesting contamination on the basis the haemoglobin spectra - but it was rejected.
 
Peer reviewers said that one fragment of ostrich haemoglobin was not enough to suggest contamination had occurred.
 
Though McIntosh accepted that his paper doesn't prove contamination, he still believes the samples may be tainted.