Fossils contain original dinosaur tissue

For many years, it was widely believed that fossils no longer contain their original organic molecules, because the fossilisation process destroys them, replacing the preserved tissue with a mineral replica. But in recent years, scientists have begun to question this dogma, with a steady trickle of papers purporting to see blood cells and other tissues in dinosaur bones, and even the signature of a blood meal in a mosquito that buzzed about millions of years ago. Now, scientists at the University of Liverpool have used a range of techniques to produce the best evidence yet that ancient fossils genuinely do still preserve these original organic materials. Steve Taylor…

Steve - We noticed that there was a controversy in the literature about soft tissue, what's soft tissue? Soft tissue is the squishy bits that should be gone, but they're not, so organic materials. And in particular, the one that intrigued us looking at bones was collagen, because a very high proportion of all animal and human bone is collagen. So the question we were asking is, is the collagen that's being reported in old bones, archaeological and paleoanthropological, is that genuine? Is it produced by microbes or is it contamination? One of the researchers in the lab or some other way.

Chris - Of course, you had some kind of headstart that this might be the case, because I remember going to a meeting in America about 20 years ago, and I met this woman, Mary Schweitzer, and she said she'd had an accident in her lab one day. It was sort of her Alexander Fleming moment where he went away, left his Petri dishes and discovered penicillin because everything grew where it shouldn't. She left some samples in cleaning solution for longer than she should have done, came back and thought, oh dear, they'll be destroyed and found there might be things that are cells in there when she looked. And people rolled their eyes and laughed at the time, but it looks like then she might've been right.

Steve - Absolutely. Mary Schweitzer, she's a great scientist. And a very determined lady, of course, because it was all the, a lot of the male colleagues who said she'd made a mistake. Well, she hadn't. And she was able to do test after test to vindicate her original conclusion that these were in fact genuine organic molecules and so on. I think it was blood cells that she first claimed to have found. But yet Mary was right, did a great job. And we referenced a number of her papers in our work.

Chris - What have you done here then to build on this and strengthen the argument and perhaps lay some of those other uncertainties to rest?

Steve - We brought together a novel combination of four analytical techniques, all of which are consistent with the idea that this is original organic material. The first one, we use laser light to look at the fossil and we find that there's organics there. That doesn't tell us that it's collagen, which is a protein that belongs to the bone. We use then what's called cross-polarised light. And what that does, it gives us a 2D scan or a 2D image of the fossil and shows actually the locations of faint traces of collagen. That does image collagen, not just organic, but it images collagen very well. Then we do what's called, it's an advanced mass spectrometry technique called bottom-up proteomics to actually get a fingerprint for the collagen and that matches collagen in modern bones. And our colleagues in the US at the University of California, Los Angeles, they have a technique of quantifying an amino acid called hydroxyproline, which is a unique collagen indicator The final part of work was done in Liverpool at the Center for Proteomics Research and they were able to sequence the collagen. Now this, it really is a smoking gun for collagen. And we were able to find that the collagen sequence that we find matched previously reported dinosaur collagen.

Chris - How far back in time have you gone? How old are the fossils you've looked at?

Steve - We started with medieval. We've gone back to Roman times, Ice Age and dinosaur and all of that work has been published. Our focus as mass spectrometrists has been upon the chemicals. What is actually there and how do we know? And so that's been our particular focus rather than anything else.

Chris - But the mere fact it's dinosaur means it's got to be at least 60 something million years old because the dinosaurs stopped being on Earth then, didn't they? So this shows that for very prolonged periods of time, the molecules that were once living, breathing dinosaurs, some of them are still there in what we used to think was just a lump of stone.

Steve - Well, that's the amazing conclusion that we get too, Chris. Yeah, these molecules have persisted throughout geological time.

Chris - It's not quite Michael Crichton's Jurassic Park yet, but it does take us a stage closer to experiencing and touching the real deal, I suppose, doesn't it? What are the implications of this? I mean, it's nice to know it's there, but can we learn things from the chemistry that we couldn't learn just from a stony replica?

Steve - Well, first of all, it does show the fantastic resolving power of modern mass spectrometric instruments, really. I mean, these are low levels of materials, low levels of collagen here. So it shows the fantastic resolving power of modern analytical techniques. And of course, they're always improving. And as they do improve, of course, we'll be able to look for other materials as well. And so there are other fragile chemicals within our bodies, within our bones, and we should be able to look for them. So it's possible. If the sequencing of dinosaur collagen is possible, then it raises the intriguing prospect. It's still a long way off of being able to sequence DNA. So that becomes a possibility and a subject of future work.