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Okay, so I have some fossils
here, and can anybody tell me
what fossils are good for?
(female speaker).
Ooh, ooh, I know!
(Dr. Johnson).
Kara.
[laughter].
(Kara).
Trace, like, identification of,
like, telling of time in
different climates, and you can
use things [unclear audio]
for trace fossils to, like,
trace back and forth, right?
(Dr. Johnson).
But that's not what
a trace fossil is.
(Kara).
I failed, I can't think.
(Dr. Johnson).
Okay, so they can be used
to tell time, and they
can be used to tell us
about past environments.
Those are two of the
major sources.
So here I have the
geologic timescale.
And we use fossils for relative
dating, and then we can,
if there are igneous rocks
or things like that nearby,
igneous or metamorphic rocks
nearby, we can date them
in those layers and then
we can get an absolute
date that we can use.
And that's how, so that's how
the geologic time scale was put
together, using relative dating
and absolute dating together.
I have a bunch of different
fossils here, and Kara
brought up the fact that we
have some fossils that are
actually body fossils and
so they're actually parts
of skeletons of organisms.
And then we have some fossils
that are just sort of evidence
of their behavior.
So, for instance, this is a
coral and this is its skeleton.
And then I have something
here, I have a smooth stone.
Does anybody know what
this might be?
(female speaker).
A gastrolith?
(Dr. Johnson).
It is, it is a gastrolith.
And what is a gastrolith,
Dr. Burns?
(Dr. Burns).
It's a stomach stone
of a dinosaur.
(Dr. Johnson).
It is, and so dinosaurs would
swallow these, and then they
would be in their, you know,
digestive tract, and
it would help them to
break up other things
that they ate.
And so this is not a body
fossil because it's not
part of its skeleton.
But you can also find tracks and
trails and things like that,
and those are evidence
of fossilized behavior.
And you can also find fossilized
poop and things like that.
So I have a variety of
different fossils here.
Does anybody want to come up
and see if you can figure out
what some of these things are?
Adam, since you're taking
paleontology, you've seen
some of these before.
(Adam).
[unclear audio].
(Dr. Johnson).
No, it's a fish, true,
this is a fish.
It's a fake fish, and so
it's supposed to be from
one of those lagerstatten,
which is the
exceptionally
preserved deposits.
Which of the lagerstatten
you think had fish in it?
(Dr. Johnson).
Solnhofen.
(Adam).
Solnhofen.
(Dr. Johnson).
Solnhofen, it's jurassic
solnhofen, is what it is, which
is a, it's a deposit in Germany
which has very, very nice sort
of chalk deposit that can be
used for making lithographs.
So that's how they
discovered it, was actually
mining the stone.
And it's exceptionally preserved
organisms, and so there's even
soft tissue preserved.
(male speaker).
Do you have shark vomit?
(Dr. Johnson).
I don't have shark vomit.
I have shark teeth,
I have teeth.
Okay, so we have some
teeth here, these are
little tiny shark teeth.
And then I have this,
this is a tooth.
Does anybody know what
kind of a tooth this is,
who would this belong to?
(male speaker).
A mastodon.
(Dr. Johnson).
Yes, this is a mastodon tooth.
And it's actually from, I
believe it's from Illinois.
And so during the pleistocene,
you know, 15,000 years ago,
these guys were
wandering around.
So there's lots of different
fossils that you can find.
You can find marine
organsims, like corals.
This is a more modern coral,
although it's still a fossil.
These are paleozoic corals,
they're solitary corals that
lived in the sea floor in, you
know, 400 million years ago.
And then this is a cephalopod,
which is like, if you
take a squid and you
stick it in a shell,
that's what a cephalopd is.
I also have some plants, because
plants get preserved sometimes,
too, and we have an
exceptionally preserved or
lagerstatten deposit
here in Illinois.
Adam, what's our lagerstatten
here in Illinois?
(Adam).
Mazon Creek.
(Dr. Johnson).
That's right.
And we have some, this isn't
from the Mazon Creek, but this
is similar to what you would
find in the Mazon Creek.
You find concretions and you
open them up and then there are
leaves and things like
that that you can find
in those concretions.
Let's see, what else?
Trilobites are always
a favorite.
And this is actually a
state fossil of Ohio,
this is the Isotelus.
And they are arthropods, so
they're kind of like pill bugs.
And you can find them
because they molt, so
they shed their exoskeleton.
You can find, they're actually
pretty easy to find,
trilobite exoskeletons
in the paleozoic.
They are extinct now, they died
at the end of the Permian,
because there was a big
extinction event.
There are five major extinction
events throughout Earth's
history, and one was at the
Permian Triassic Boundary.
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