This series of episodes is brought to you by The Field Museum,
the Harvard Museum of Comparative Zoology, and the National Science Foundation.
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[Emily]: Hey we're back here at the Museum of Comparative Zoology with Dr. Stephanie Pierce
Stephanie, what do you do here at the Museum?
[Stephanie]: Well, I'm the curator of vertebrate paleontology
and I study the anatomy and the function of both modern and extinct animals.
[Emily]: And today we're going to talk about that Bending Experiment
that they just did.
Yeah! [Stephanie]: (yay)
[Emily]: So, in our last episode
um, Katrina and I were focusing kind of on the vertebral column of that fisher
and, once the camera stopped rolling, what happened next?
[Stephanie]: Well, once you get the vertebral column out is really when the science begins.
What we did was we took that vertebral column and we separated out into joints.
And so a joint is composed of two vertebrae.
So we have one bone process in the front and one in the back and between there is a joints.
And those joints allow the vertebrae to move.
[Emily]: So you have a little duos of a little vertebral sections? [Stephanie]: Exactly.
[Emily]: And so what was part of that process?
[Stephanie]: We stick some screws in it. So you stick a screw in one vertebra and in the other vertebra,
and then we sort of cranck it in this rig to give some rigidity.
[Stephanie]: We stick some pins on the top, and those pins will gonna allow us to look
if there's any movement while we stick some weight to one of these screws.
[Stephanie]: So we do this in a small increment so we can understand the process
by which the vertebrae actually move with respect of one to another.
[Emily]: And so, putting the weights on it, what did you guys learn about this particular set of vertebrae?
[Stephanie]: Well, the interesting thing about the lumbar vertebrae is that they are really mobile,
but it takes a lot of mass, or a lot of force in order to get the vertebrae to move.
[Stephanie]: When you wanna move really fast, so in a mammal, when they want to gallop and run really fast, like something like a cheetah,
they can actually use those big muscles in their back, like you saw in the fisher cat,
to create a lot of force and move those joints in the lumbar region.
[Emily]: And we know this all comes back to like looking at protomammals or fossil mammals,
and they don't seem to have that lumbar region.
[Emily]: How do you compare what we did with the living fisher - you know, it's dead, but...
the version of a living mammal and compare that to a fossil animal?
[Stephanie]: It is actually not that easy, but luckily we have a lot of new technology that helps us out.
[Stephanie]: So, the first thing we need to do is to isolate the vertebral column in our fossils.
One way we can do that is by doing CT scanning,
and what the CT scan allows us to do is look at the difference between the fossil and the rock.
And we can actually pull that fossil out of the rock, virtually.
[Stephanie]: So we can take a CT scan model and we can make a virtual replication of the vertebral column, and we can conduct a virtual bending experiment.
[Emily]: Cool. So, when you get to the CT scanning model into your computer software, how can you perform that similar experiment?
[Stephanie]: I actually use gaming software..
[Emily]: Oh, really? [Stephanie]: Yeah.
[Stephanie]: So the gaming industry is really great for 3D modeling
and so, what we are actually doing here is making 3D models.
[Stephanie]: When a vertebral goes in, a lot of times, it's not in its best form, it doesn't look pretty. [Emily]: Yeah.
[Stephanie]: Here is one model where we put in, (...) all over the place
[Emily]: That is a little scoliosis like. [Stephanie]: Exactly.
[Stephanie]: And here is the same animal, but all the vertebrae are put into place
[Stephanie]: And once we get into a reasonable shape, we can start to play around with it.
[Stephanie]: Remember back to our bending experiment? We had two vertebrae,
and it had a joint in the between, and we were trying to experiment with how did that joint move?
[Stephanie]: Here we have two vertebrae, and there is a joint in between it.
[Stephanie]: So what we can start to do, is that we can start to manipulate this,
we can use the software to move things with respect to one another.
[Emily]: So how do you know that you are not going to an extreme?
Because you can bend it pretty far one way, but it seems like that might be a little gratuitous of the software you are using.
[Stephanie]: As a scientist, if you are doing something like this, you really have to pay attention.
[Stephanie]: You could just do whatever you wanted, it's virtual.
[Stephanie]: But what you want to do is really look at the anatomy of the vertebral column, all of those joints.
[Stephanie] And if you, for instance, disarticulate a joint, it might tell you that maybe you've gone a little bit too far.
[Stephanie]: Or if you start to merge one bone into another, you also might have gone a bit too far, so
sometimes we call this disarticulation and bony stops.
[Stephanie]: When we look at normal bending experiments, we can say, this joint can move this much, and this is the anatomy of those vertebrae.
[Stephanie]: And so we can make correlations between the anatomy of the vertebra and how much that vertebra can bend.
[Stephanie]: And that would give us some sort of bound.
[Emily]: So you are not only looking at this fisher cat, you are also looking at the number of other animals that are still alive, right?
[Stephanie]: Yeah, that's right. We are looking at a variety of different animals that have different morphologies.
So we are looking at things like lizards, monotremes, marsupials, and a variety of placental mammals too, like the fisher cat.
[Stephanie]: By looking at the variety of modern animals, and doing all these bending experiments,
we can understand how their joints actually function.
[Stephanie]: And then we can do virtual bending experiments on the same animals,
and put them on the same parameters, as our fossils, and we can compare that.
[Stephanie]: We call this "validating our experiment".
[Stephanie]: And so if the two- if the bending experiment and the virtual bending experiment in the modern animals match up really well,
we can be pretty confident that our virtual experiment in our fossils are giving us a pretty good indication of the type of mobility
and the potential for locomotion behavior.
[Emily]: So what is the ultimate goal of all of this research?
[Stephanie]: Well, our ultimate goal is to really track the evolution of the vertebral column
through the fossil animals that lead up to modern mammals.
[Stephanie]: Test how much regionalisation is in the vertebral column and how that correlates with function.
[Stephanie]: And hopefully we will try to pinpoint the time in which the mammalian type regionalisation and locomotion style evolved.
[Emily]: That's so exciting, I mean, you are looking at fossil evidence that was probably collected, you know, in the last fifty to a hundred years.
[Emily]: You're being able to manipulate it using computer software without doing any damage to the specimen,
and you were able to make inferences about the mobility and gait of animals that lived hundred of millions of years ago.
[Stephanie]: I think right now, it's the one of the best times to be a vertebrate palaeontologist.
[Emily] That's pretty exciting. [Stephanie]: I think it's pretty exciting.
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