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From dinosaur bones to dinosaur teeth, scientists have found plenty of evidence of Earth's long-extinct inhabitants. Now, some scientists think they've unearthed something that's never been definitively found before - dinosaur blood. NPR's Nate Rott reports.
NATE ROTT, BYLINE: To be clear right from the get-go, we're not talking about a vial of dinosaur blood. So put those "Jurassic Park" dreams to bed. The sample in question is, well...
KLITI GRICE: Yeah, it just looks like a bunch of old bones.
ROTT: Because that's what it is, says Kliti Grice.
GRICE: It's 115 million years old, but it has extraordinary preservation.
ROTT: Which is why it was sent to her. Grice is an organic geochemist at Curtin University in Perth, Australia, who specializes in looking for molecules in ancient fossils. And she says when she looked closely at the bone, like really closely with a very powerful microscope...
GRICE: It was actually remarkable.
ROTT: She could see vascular canals where blood vessels would have run through the bone.
GRICE: And within the vascular canals, you can see these red blood cell-like structures.
ROTT: Like being the key word. They resembled red blood cells or what the fossilized/mineralized versions of them might be, but that doesn't mean that's what they are. So Grice did a bunch of fancy chemistry to test them further.
GRICE: This sample went through about 30 different analytical techniques, I would say. Very exhaustive chemical process.
ROTT: And perhaps most compellingly, they found evidence of a molecule called heme.
GRICE: Heme is part of hemoglobin, which is the iron-containing molecule that helps to transport oxygen around the body.
ROTT: So biologically, yeah, it's pretty important. Heme is also what gives blood its red coloring. In her new study published in the Proceedings of the National Academy of Sciences, Grice says this is the first time heme has been detected in a dinosaur fossil in a vascular canal.
GRICE: So I'm quietly confident that these may be red blood cells.
ROTT: Other scientists are not as sure.
SANDRA SILJESTROM: It's tantalizing, but maybe I'm not completely convinced.
ROTT: Sandra Siljestrom is an organic geochemist at RISE Research Institutes in Sweden.
SILJESTROM: With the chemistry, I find some of the data very convincing. It's very well done.
ROTT: But she also says the data is a little bit noisy.
SILJESTROM: And it's understandable because, you know, the blood cells is not that big, right? So, you know, the signal from individual blood cells is obviously going to be very small.
ROTT: Especially in one that's more than a hundred million years old. Other scientists have questioned the morphology, or the structure, of the maybe red blood cells Grice found, pointing out they're not the right size and don't have a nucleus, which is a feature of bird and crocodile red blood cells. Grice argues we don't really know what a mineralized red blood cell should look like, but she agrees the morphology alone is not that convincing.
GRICE: I think that's the weakest part of the paper, but you have to collectively look at the evidence.
ROTT: The chemistry, the location of these maybe cells, the concentration of them. And in her opinion, that all adds up to evidence of dinosaur blood. She hopes applying the method she used in this study on other dinosaur and ancient animal bones will prove it once and for all. Nate Rott, NPR News.
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