Will we ever see dinosaur DNA?
In recent years opinion has shifted to accept that even ancient fossils most likely also contain some of the chemicals that were present in the original lifeform, including proteins, fats and possibly DNA. This is known as molecular palaeontology. Landon Anderson works on this at North Carolina State University where he’s currently finishing his PhD…
Landon - You know, when someone would go out into the field and dig up a fossil, sure it would have the shape and structure of a bone. But the general view on that was that minerals had come in and replaced the original organics that were there and that would now just be a replica of the original organism, skeleton, or bone. And that was for a while, the general view of what a fossil was.
Chris - So it was the form, but none of the fabric of the thing that had once lived.
Landon - Yes. And even for a while, we didn't even know whether the original, like microscopic structure of the bone itself was preserved. Do you know where all the blood vessels had been or, you know, the cells in the bone had been, whether that was preserved as well.
Chris - So when did that begin to change? When did our view begin to shift?
Landon - That view, that the overall fossil bone is not just a rock replacement or mineral replacement of what was originally there, changed roughly around the turn of the 1900s to the 21st century when paleontologists began to look at the microscopic structure of fossil bone, or fossils in general. For example, if they had a bone of a dinosaur, they could take thin sections of the bone and look at it with a microscope. The actual tissue structure was at least replicated in minerals. So you could see what the structure of the bone was like when the organism was alive. That was sort of around when we started to figure out there might be something more to these fossil bones than we had previously thought.
Chris - And what was that insight or what data or discovery began to provoke people to think that this isn't just well preserved micro structure, that there are things in there that might be part of the original beast or being that gave rise to that fossil?
Landon - The major discovery is around 2005, Mary Schweitzer actually reported out of a T-Rex bone from the Hell Creek in Montana, the presence of soft, flexible blood vessels and cells and really changed the way that paleontologists kind of viewed fossils in general. They weren't just these mineral replicas of the original organism, but some of the original tissue might be there. And if that's the case, then there's a chance that it can tell us what it looked like and how it lived back when it was alive.
Chris - I met Mary Schweitzer about six or eight months after she published that paper you just referred to. And she told me that the scientific community, when she stood up at a conference andsaid, I think I've got original tissue from a T-Rex, people laughed at her and told her she was misguided and must have done her experiments wrong. Presumably that view has now changed.
Landon - Yeah. When Dr. Schweitzer first recorded her findings, there was a lot of controversy. One of the main ideas or hypotheses proposed to explain the soft tissues in the case of they weren't original soft tissue, was that they might be bacterial biofilms. But over the years that has been tested and the data in general supports that these are indeed the original soft tissues scientists are finding in these bones.
Chris - I almost feel like it's sort of bringing colour television to previously black and white images. It's almost like another dimension in paleontology that we are into now with this. So what can it add that we couldn't get just by looking at structure before?
Landon - Well for one, just for like the organismal biology, these ancient organisms in general, we can learn things about them through their soft tissues and the chemicals preserved in them and that we otherwise would have no other way of knowing. So it can tell us a lot about their biological adaptations to their environment, kind of how they lived.
Chris - DNA must be one of the holy grails here, a horrible phrase, but it must be one of the things that's a target because it can tell us so much about the evolutionary history of an organism, where it came from, who it's related to and so on. We are in the sort of million year regime of published data on ancient things with DNA in them. Do you think it's feasible we're gonna see T-Rex DNA in the near future?
Landon - Oh man, that's a big question. Everyone likes to know the answer to will we ever get dinosaur DNA and after that, obviously whether we'll ever be able to clone dinosaurs. There are studies out there, one recently published that reported not DNA sequences, but the presence of some structure that may be DNA. They haven't actually sequenced it yet, but they used a chemical that binds specifically to the double helix structure of DNA and they were able to show that this chemical actually bound to a specific location within what they reported as cartilage cells from a duck-billed dinosaur. Will we ever be able to sequence that? That's a whole another question because to sequence DNA, the reactions necessary require it to not be heavily damaged. And obviously to get that in a dinosaur fossil, pristine DNA, it's a bit of a challenge.