Just as The Lost World hits the theaters with its bloodthirsty tyrannosaurs, scientists say they have turned the tables by extracting blood--or at least one of its key components, hemoglobin--from a T. rex bone. If the finding holds up, it would give scientists an extremely powerful way to trace the evolution of the giant theropods. But some experts are skeptical, saying that the results are more likely to be due to contamination than to dino blood.
In the current issue of the Proceedings of the National Academy of Sciences, researchers from Montana State University, Indiana University, and the University of Wyoming report that they have found hemoglobin, the oxygen-carrying protein in blood, in a 65- to 67-million-year-old T. rex bone. The team, led by Montana's Mary Schweitzer, extracted material from the fossil and tested it with a battery of techniques, including ultraviolet, visible, and Raman spectroscopy, nuclear magnetic resonance, and electron spin resonance. In each case, the researchers claim, the data suggest that the sample contains a molecule that looks like the core of hemoglobin. The researchers also found that a sample of the bone injected into rats yielded antibodies. "That's one of the things that clinches [the identification of the blood]," says Peggy Ostrom, a geochemist at Michigan State. And the compound, whatever it is, in the bone apparently resembles bird hemoglobin--just what is expected of dinosaur hemoglobin, if the popular theory that birds descended from dinosaurs is correct.
If hemoglobin can be found in other samples, researchers trying to trace the dinosaur family tree will have a powerful new tool. Small variations in hemoglobin in different species can show how closely related they are, so hemoglobin from the bones of various dinosaurs could trace their evolution with unprecedented precision. But many researchers are putting long odds against the finding, because hemoglobin is generally too scarce and fragile to last long in fossils. "You start out with very little, so it rapidly falls below detectable levels," says Noreen Tuross, a biogeochemist at the Smithsonian Institution's Conservation Analytical Laboratory. "Even at 50,000 years, you hardly ever find hemoglobin."
"The likelihood that they have really found this is very small indeed," adds Matthew Collins, a geochemist at the University of Newcastle in England. But that chance is enough to keep the Montana team in action. So while audiences thrill to Steven Spielberg's digital monsters, scientists will continue trying to wrest blood from petrified bones to understand the real thing.