The scientists describe re-analysis of the T. rex data and also report finding evidence of substances found in collagen.

'In summary, we find nothing obviously wrong with the Tyrannosaurus rex [analysis from 2007],' the report states.

'The identified peptides seem consistent with a sample containing old, quite possibly very ancient, bird-like bone, contaminated with only fairly explicable proteins.

'Haemoglobin and collagen are plausible proteins found in fossil bone, because they are two of the most abundant proteins in bone and bone marrow,' the authors said.

The findings are slated for publication in the September issue of the Journal of Proteome Research.