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Thank you. - [Narrator] This is what
Wyoming looks like today. Towns, roads and ranches. Cows can be seen everywhere. Wolves and bison are
making a comeback. If we go back 500 years, we see villages, pathways
and migration corridors. Humans have an impact
on the landscape but not to the degree
of modern times. Wildlife are plentiful, there are huge herds of bison, bighorn sheep and elk. Wolves roam vast areas
of territory and horses have not yet been
reintroduced to the Americas. But what if we go back
13,000 years and before? What did Wyoming look like then, and why has it changed? At the northern
most edge of Wyoming in the Bighorn
Mountains lies a cave that has been collecting
information on that very subject for over 40,000 years. (hinges squeal) (country acoustic guitar) - [Announcer] Production
funding for Main Street Wyoming is provided in part by the Wheeler Family
Foundation of Casper, and by the Members
of Wyoming PBS. Thank you! - First time I was in
Natural Trap was in 1967, we would drive up to the cave and rig off the axle of our
vehicle and drop the rope in, and we'd rappel in
and climb back out, rappel down and climb back out. At the bottom of the cave
was actually a mound, and that mound was
really soft and crumbly and had bones and stuff in
it, but it was all modern, you know, rabbits and
deer and things like that that had fallen in. - [Julie] Natural Trap Cave is
located in northern Wyoming. It's at the base of
the Bighorn Mountains, right near the
Bighorn Reservoir. Natural Trap Cave
is a karst cave, it's made out of limestone. Water percolates in
through the limestone and then it dissolves
away the interior, leaving just a shell, and then when the
opening falls in, it's very similar to
how a sinkhole forms, but instead of forming a
sinkhole it forms this cave. - It's called Natural Trap
because things fall in, and the reason why the
grate is there is because, you know, we didn't want
people and cars going in there, the BLM didn't want people
and cars going in there. - [Narrator] Starting in 1970 Dr. Lawrence Loendorf
helped to recognize the scientific significance
of Natural Trap Cave by conducting an exploratory
excavation of the cave, as well as taking steps to preserve the integrity
of the specimens there for future research. By the mid 1970s a
team of paleontologists led by Larry Martin from
the University of Kansas and Miles Gilbert from
the University of Missouri began the first major
excavations of the site. What they found was one of the
most complete fossil records spanning from the Pleistocene
into the Holocene. - [Julie] The Pleistocene epoch
is also known as the Ice Age because of the cold
fluctuations that occurred during that time. The Pleistocene epoch lasted from about 1.2 million years ago to about 11 1/2
thousand years ago. Many of the megafauna,
or large mammal species, that existing during
that time went extinct, such as saber tooth cats, dire
wolves, short faced bears, camels, mammoths and mastodons. All of those things went
extinct right around that time, and that's the border between what we call the
Pleistocene and the Holocene. So the end Pleistocene
extinction event is a conundrum that many scientists
have been thinking about for a long time. - The primary ideas
are human influence, when humans came
to North America they wiped out
all the megafauna, the large mammals, for eating. The other hypothesis is
that climate change did it, and that makes sense because that's when the
glaciers were also going away, and large mammals tend to
be particularly sensitive to climate change. - [Julie] Our project doesn't
really take into account human arrival, but we are
looking at how climate affected the animals both
in their genetic material and in their morphology,
and we're correlating that with the pollen data
that we're collecting so we can recreate the flora at Natural Trap
Cave at that time. So we try to get an
entire recreation of the end Pleistocene
habitat in northern Wyoming. - [Jenny] Natural Trap Cave is
a challenging place to work. I say I have a very
strenuous commute every day to get to my field site. - [Julie] It's such
a complicated project because of how you have
to get into the site. Since there's no
other way to get in you have to rappel
in on a single rope and you have to ascend out using hand ascenders
and your own steam. - [Jenny] We've put
out an announcement to the Cavers' Societies, the
grottos, the local grottos, and we had people
show up in droves, and they have been the most
incredible helpful people. They really take initiative and have been incredibly
integral to the process. One in particular who's
our Head of Safety, he's been volunteering for
weeks at a time every summer in order to make
this project happen and we absolutely couldn't
have done it without him and without other members
of the Wyoming community. - The uniqueness of
this cave is twofold. One is that it's a pit cave
that is on top of a ridge, so it funnels traffic, animal
traffic, down this ridge and then, also unique to
this particular pit cave, is that just before you come to the 15 foot
hole in the ground, there's a little drop
off so you don't see it until you're right on top of it, and then it's almost too late, and it has been
for many animals. This particular cave has
an 82 foot entrance drop, it's about a 15
foot diameter hole and it bells out in all
directions from that hole. We go down the ladder
onto this ledge, we have safety lines, and then there's a grid
over the top of the cave to keep people and animals
from falling in now, and we do all our rope
rigging off of that, but to access this cave you have to rappel
in and ascend out. I can't train people to be super
proficient vertical cavers, there's no way in the short
amount of time we have, I get 'em to a level
that I feel comfortable that I can effect a rescue. - [Julie] Natural Trap Cave is a really important
fossil site, not only because of
the quantity of fossils that are coming out, but also because of the
preservation of the fossils. The cave is always cold. It never gets above about
42 degrees Fahrenheit. It's also very wet, probably
about 80 to 90% humidity, making it a little bit like
your refrigerator at home. This site can really inform us of not only changes in genetic
variability in the animals but also of the environment
in northern Wyoming during the last Ice Age. (slide guitar) - [Narrator] The team has set up three active excavation
sites within the cave. They're known as
the Bison Saddle, the Cheetah Pit
and the Catacombs based on some of the early
specimens out of each of them. The excavation work is primarily
conducted by volunteers under the supervision
of lead scientists in their respective fields. The volunteers are members
of the caving community, students in related fields and others just interested in the scientific
significance of the cave. For Dr. Julie Meachen, her
field of expertise is megafauna. She is interested in the
functional morphology of the large mammal
remains in the cave. - [Julie] Functional morphology is the study of body
form and function, so like a cheetah would have
a much shorter upper arm or humerus than it would
lower arm bones or radius, whereas something that
climbed for a living would have a much longer upper
arm bone than lower arm bone. So in terms of fossil material, we're looking for
diagnostic pieces. We need to be able to identify
the species that it came from and the body part
that it came from. - It's in three pieces. - [Julie] Oh, it's
in three pieces, wow. - But they're well
fitting pieces. - They are, this is another
proximal metapodial of a cat. When we have a lot
of people down here, as a team leader my job
is basically to run around and manage everybody, help the volunteers
identify specimens, so I don't get to do a whole
lot of excavating myself. Nice, that's
definitely a carnivore. Looks like a, a wolf,
yeah, nicely done. - I've been joking that I've
been playing stone vs. bone this whole time, you know, trying to tell what's a
rock versus what's a bone, so when you find something
that for sure is bone and you can start
trying identifying it, it's pretty exciting. As a volunteer I
feel like for me it's been an even bigger
learning experience than for a lot of the
scientists and professors and everyone who have years
of experience with this. There's bone right
on here, here, here, that's all sections of bone, and we pulled a piece that
broke right out of here so we believe that
probably, hopefully, this is all from the same horse. So that maybe even
could be a tooth, we'll see once I
dig out the ends, but the side looks similar and has some of
those same divots. - [Andy] When you're
digging for fossils, most of the time you
don't find anything. You're just digging
through all the dirt and all you're finding
is more dirt and rocks. But when you see a piece of
bone sticking out of the ground, and you dig around a little
more and a little more, and you figure out
it's something big
that's buried there, that's extremely exciting. Well, if you think about
digging up dinosaur bones that have been sitting
out in the desert for a hundred million years, they've pretty much
turned to rock. These bones have
only been down here for maybe 10,000 years,
15,000 years, 20,000 years, something like that,
so they haven't, they're actually still bone,
they haven't mineralised yet. This area, since we're right
under the hole of the cave, this is where water's
gonna come through, so these sediments are
fairly waterlogged, which means that the bones
are not gonna really dry out, which keeps them pretty fragile. It's a vertebra of something,
not sure what, not yet. And the problem is
that it's in mud, which is making it very fragile, and it's also
surrounded by gravel. So I have to dig around the
rocks to get the rocks out and then dig around the
fossil to get the fossil out, so it's taking a very long time. So you can even see how it's starting to
come apart a little bit, right there, so see how
it's broken right there? So what I'm trying to do
is not break that more, so I have to be very careful
when I'm taking the rocks out. - [Natalie] So here's
that whole tooth there, the dirt starts to crumble off. I feel lucky that this is my
first paleontology experience. Finding a lot of things! A lot of field sites are
not as productive as this, and even within this field site a lot of the areas aren't
as productive as this wall. - How about A12? - Two oh one. - What's A1? - A1 is two oh two. - [Landon] This instrument
measures distance and then horizontal
angle and vertical angle, and so it takes those
three bits of information and the computer
can extract that and turn it into x,
y, z coordinates, and so that way we
end up with a grid, and then we can
bring it into CAD and then you can
look at it and say, okay, this bone was
sitting this way, this one was sitting this way, and then you can
map it like that. It's probably going to be
our last chance to be in here for a while and I just wanna
make sure everything's right. This is pretty high up in
cool things that I've done. It's exciting to be
part of the project. - [Natalie] When we find a bone we do take measurements
of the elevation that it was found at, the
position it was found in, what section of the
grid it was found in. For this one specifically, since we're digging
up all these teeth right in the same area, we have
a range where they're found so you know that they
were found together. - [Julie] So there's a
giant grate over the cave because in 1971 someone
almost drove their VW Beetle into the cave, so big things
don't fall in any longer but small things get
trapped all the time. Some of the things that we
have found over the years include several pack rats. The first one, we actually
named him Packy LePew, and we did a taphonomy
experiment on him. Taphonomy is the study of
the breakdown of tissues and the process
of fossilization. This is actually
Packy right here. Packy is very hard and
desiccated, he's very dried out. He's been here the whole time and he's basically
just a packet of bones with some skin on it and fur. - Pack rats are super cool. They make these giant nests and there's pack rat nests
along the rim of the cave. They go out and they
collect every bone and every cool piece
of wood that they find within a five
kilometer diameter. You can imagine these wood rats precariously perching
on the rim of the cave, and then they're
scurrying around and they kick all their prize
treasures down into the cave, and so you get this
rain of fossils coming down into the cave. It creates this really nice
dense concentration of bones that gives us a really clear
picture of the community. - We've radiocarbon
dated a lot of bones. We're getting age ranges ranging from about 2,000 years all the way down
to 30,000 years, and so we're trying to
really pinpoint exactly where each of those different
stratographic layers is. - [John] We tore off
all the top of this, which is all recent stuff, and
then there's this red layer, and you can see this
red layer right here, which is full of
some recent bits. It's old, but not
as old as we want. And then we're in
this gray layer, which is the youngest
layer that we care about. Zero is everything above. And so we're carefully trying
to not go to the next layer which you're already seeing
which is rocky, the next layer. - [Jenny] So there's
a whole process to collecting the microfauna. Because the bones are so small, it's really difficult
to just excavate in the same way that we
doing for the megafauna. So what we do instead is we take out really
large sacks of sediment. It's dirt and rocks and
bones all mixed together. - [John] And we're taking
off one layer at a time and putting it in bags, and then Dr. McGuire's gonna
take it back to Georgia Tech and sift through all of these and look for all the
microfossils that
she told you about. We'll take it up one layer
at a time, clean it off then go to the next layer, and
then do that for four layers. - [Jenny] If this fossil site
were not 80 feet below ground, then I would be able to pull
out so much more sediment, and I would be able to
have a lot more microfauna in order to do my analyses, and I'm having to
be very efficient because we're a
little bit limited in having to ask our friends to pull all of this dirt up
these ropes every day, right? - In all this dirt you
can't see anything, so we put it in screens and
then we wash away the dirt and it leaves us with
the small fossils that we can then identify. We're doing the quick and
dirty screen washing on site so we don't have to bring
60 pound bags of dirt home, we only have to bring 10 pounds
of little rocks and pebbles to sift through
in the laboratory. For the one large, like 40 or
60 pounds worth of sediment, it's reduced to basically this, so that's not too bad. People who are interested in
paleontology who wanna help, this is that perfect
thing for them. Just poke through and anything
you think might be a fossil you set it aside, and that way she'll only have maybe a
cupful of things to look at, rather than thousands
and thousands and thousands of specimens. So, in paleontology we
love our volunteers. - [Jenny] As we're picking
through the microfossils, the biological
gold are the teeth. So we can really identify
a species very easily from the teeth, and especially
if we find a mandible or a maxilla, which is
an upper or lower jaw. If it has teeth in it we'll
always put that in a little vial so that, in case the
teeth fall out of it, we'll know that that's
associated material. - [Penny] For me, I get most
excited if I can find teeth, because my research depends
upon large mammal teeth. So any teeth we find that
I decide I want to sample somehow make their way to
the laboratory in Rochester where I clean it out and
pull out my dental drills and drill the samples and put
them in the mass spectrometer, so that we can not
only figure out what the animal was eating, but also what time of
year it was eating that, and we can also look at how
much it rained and at what time, and get a general sense
of temperature variations, which is really cool stuff to be able to understand what
was going on in past climate. - One of the ways that we
do paleoecology effectively is that we try to bring in
multiple lines of evidence, and the isotopic record gives
us a sense of the environment that isn't showing up
in the pollen record. Pollen is the most common fossil on the terrestrial landscape. It's produced every year
in massive quantities. Other things can decay,
leaves can get broken, but pollen, it's at
the micron scale. We go to the sediment wall
and you clean the face off, and then every centimeter you
take a little bit of material and put it into a bag. We ended up with
over 500 samples from this centimeter
thick unit of dirt. We functionally digest it. Pollen is like a natural plastic and so it's really
resistant to chemicals and so we can dissolve the rock and we can dissolve
other organic material and the pollen
grains will remain. By looking at each sample
through this sequence of dirt we're able to look at changes in the relative abundance
of different pollen types, and we use that to infer what
the environment was doing. - [Julie] So all the fossils that we are excavating
in our time here are all being deposited
in the collections at the University of
Wyoming Geological Museum. - [Laura] So here we have
just a small subsampling of bones from the
Natural Trap Cave. I use the information
that she's provided and we enter it
into our database, and this is a large
scale database that includes all
the information that we could ever want to
know about these specimens, and then we have to figure
out how to curate them in a way that will preserve
the bones for eternity. Right now, what
we're trying to do is essentially play Tetris. For example, in this tray
over here we have bird bones with horse bones, with
American cheetah bones and bunny bones, or lagomorphs. So these are not
gonna stay here, it's just a holding pattern while we figure out
where they're gonna go. And we're trying to ensure that the different types
of animals are organized with like taxon, and we're
also trying to organize them by the different
stratographic locality in which they were found. Digitizing and imaging them
is a very important step in fossil curation, and that's because only
a few hundred people get to enter this room and
physically look at the bones. And so we have to get the
information out somehow and so our database we
have available via the web, and we're ultimately gonna
have pictures of every bone, and we're going to have 3D
models of some of the bones available for folks to download. And so for really large bones we'll just use a regular
high end digital camera, but we also have a scanner and they will basically
take a 3D model of the bone, and make it so that you can
look at it and 3D print it just like this one
that I'm holding here. Specimens that are smaller,
we have a digitizing station, and that's where we take
really detailed pictures under high magnification. That enables researchers
to see features that you wouldn't
normally get to see, as well as give a
really accurate picture
of each specimen. I'm really excited to
have this collection because this is going to be one of the first
Wyoming fossil sites that will stay in Wyoming. Curating the Natural
Trap Cave specimens here makes our collection
that much more important, and so it's a really
good benefit for us because it will bring
more researchers to the state of Wyoming and
the University of Wyoming. - [Tom] It's really fun because we're
operating in a world that had ice sheets over it, and horses, and camels,
and dire wolves, and mammoths, and
mastodons, and no people, and you're just thinking
about the world that you know but it's so foreign, and we're transitting it
through these data sets. - [Laura] Rarely
do you get a site that has such a natural
accumulation of specimens. It's a very unbiased record, so what we see here is what
actually lived on the surface in a really kind
of true snapshot. So that alone makes
this collection a really unique collection because it gives us a
really reliable indicator of what lived in Wyoming
10, 20, 30,000 years ago. - [Julie] How does this relate
to what's happening today? In Africa, for example, we
have the imminent extinction of rhinoceroses and
we have elephants that are very endangered, and so what do we expect to
see in that type of community? And there is some evidence
that in North America, as you have mammoths
going extinct, then what you end up seeing is a real expansion
of forest systems because they're no
longer being controlled by the megafauna that
are on the landscape. - Wyoming has experienced
long periods of drought. We have studies that
suggest droughts lasting hundreds if
not thousands of years. One thing that we
would wanna know, at the resource
management level, is how do our natural
systems respond to a deficit in water
that is 500 years, a thousand years? Because these things happen, we can expect them
to happen again, and that's important for
our ranching industry, our communities, everything
depends on water, and one of the
things we want to do is to use this
paleoenvironmental information out of these obscure
pollen grains and fossils. And so we're really
pushing the data to answer societally
relevant questions. - [Narrator] The cave
has already begun to provide a clearer
picture of the past. As Julie and her team publish
the results of their research, the scientific community
will have an opportunity to further update the
paleolithic record. The sealed cave will continue
to preserve its treasures as new research techniques
and technologies are developed to recover even more data, advancing our understanding
of the world we inhabit. All thanks to this unassuming
pit in Wyoming's landscape known as Natural Trap Cave. (slide guitar and harmonica) - [Announcer] Production
funding for Main Street Wyoming is provided in part by the Wheeler Family
Foundation of Casper and by the Members
of Wyoming PBS. Thank you!
