Scientists have discovered decayed bones, flesh, skin and organs of dinosaurs that are millions of years old. Now, there is evidence of blood cells with protein intact, Gizmodo reports.

Scientists are able to use new methods to see deep inside of fossils. They used these new methods to publish a study of the structures of dinosaur bones in this week's issue of Nature Communications.

The study backs up previous discoveries of soft-tissues in dinosaurs. In the past these discoveries have been controversial and experts believed that it was contamination.

A specialized tool called a focused ion beam was used to slice through bones by Sergio Bertazzo. This tool helps leave pristine surfaces that allow for high-resolution images to be displayed.

Bertazzo expected to see bone crystallites; instead he and his partner saw soft-tissue. He said this was "completely unexpected" and that he thought the results were "not real" at first.

Bertazzo and his team found round structures that looked like red blood cells and strands that looked like the protein collagen.

The team then ran a chemical analysis to determine what they saw. They found that the blood cells were similar to those of an emu, who are relatives of dinosaurs. They also found that the collagen seemed to be made up of amino acids that are known to be common in the protein. The analysis is encouraging that soft-tissues may be able to be preserved in very old fossils.

To prove the doubters that say the proteins and amino acids found in the bones are contaminants wrong, the team plans to use a different type of mass spectrometer, Science Mag reports. This tool can provide the sequence of amino acids in a protein fragment and would back up their claims that suggest the presence of collagen.