Researchers found Iron may be making ancient fossilized tissue harder to detect, but also aids in their preservation.
In 2005 Mary Schweitzer, "an NC State paleontologist with a joint appointment at the N. C. Museum of Natural Sciences" found T. Rex tissue that was "surprisingly " well preserved, a North Carolina State University news release reported.
"Iron is necessary for survival, but it's also highly reactive and destructive in living tissues, which is why our bodies have proteins that transport iron molecules to where they are needed but protect us from unwanted reactions at the same time," Schweitzer said. "When we die, that protective mechanism breaks down and the iron is turned loose on our tissues - and that destructive process can act in much the same way formaldehyde does to preserve the tissues and proteins."
Birds and crocodiles (close relatives of the dinosaur) have larger nucleated red blood cells than mammals, this means they have more hemoglobin per cell. Since dinosaurs are so close to these animals it is likely their cells had similar properties. The extra hemoglobin would allow iron to give the tissue a preservation boost. If this hemoglobin was contained in protective shell (such as a bone) it would have a higher chance of staying intact.
When a research team removed the iron from tissues of the T. rex and a Brachyolophosaurus the fossilized flesh reacted much more strongly to antibodies that detect protein; suggesting the iron was not only aiding in the tissue's preservation, but helping it to hide as well.
To test their theory the researchers soaked blood vessels taken from modern-day ostrich bone and soaked some in water and others in hemoglobin from red blood cells. Over the course of two years the water-soaked vessels deteriorated while the vessels soaking in hemoglobin remained intact.
"We know that iron is always present in large quantities when we find well-preserved fossils, and we have found original vascular tissues within the bones of these animals, which would be a very hemoglobin-rich environment after they died," Schweitzer said. "We also know that iron hinders just about every technique we have to detect proteins. So iron looks like it may be both the mechanism for preservation and the reason why we've had problems finding and analyzing proteins that are preserved."
