And we have a very unique kind of fossil that we find, and
indeed it's the state fossil.
Every country, every state, every place, depending on what fossils
are abundant there, they name one of those fossils a state or a country fossil.
The state of Illinois,
the fossil here is called a Tully Monster, and a Tully monster.
It looks something like a segmented worm
that has some jaws on the end with a mouth.
And it's very bizarre looking because it had a very small mouth and
jaw system and then it had a very long neck.
And then it kind of inflated out to be a segmented worm like central body
that had a bit of a flipper on the end.
So, the Tully Monster is a weirdo, but it's extremely common in the state
of Illinois and the reason it's common is that during the Paleozoic,
one of the time periods of that is called the Pennsylvanian and
when you're in Europe and other places the Mississippian and
Pennsylvanian are combined into a time period called the Carboniferous.
And the Carboniferous is the great age of the coals.
And so, the Carboniferous in Europe was split into two divisions.
The earlier one is called Mississippian and
the later one is called the Pennsylvanian here in the United States.
And so this great time period of the age of coals, the coals were formed from
having incredibly well developed forests that grew out into marshy areas.
And it was also a time period of having the oceans be relatively high because
we had little to no ice on the planet.
So all the ice that's normal bound up in the oceans,
release back into the water and sea level becomes very high.
So all the conditions were right to have a lot of organic matter deposited quickly
along the margins of the oceans and especially in deltaic systems and marsh
systems that were right on the borderline between the coastal regions of the world.
These very thick coal deposits were very important at the time period.
And in coal swamps you have a suite of environmental constraints that are just
right to preserve very fragile organisms if they die and fall to the water.
And these waters are very low in oxygen and because they're
low then they have a unique suite of microbes that live in the waters.
And then you have the ability to have very high rates of sedimentation,
very quick burial of something that dies and falls into the water.
So the coal swamps are a great place to make fossils.
The Tully monster is an example of that.
The Tully monsters lived in these coal swamps and when they died and
their bodies hit the bottom of the swamp before they could be eaten by
something else it wasn't uncommon for them to be buried very quickly.
And they were buried in environments where the oxygen levels were very low and
it allowed to have this very unique, beautiful,
perfect preservation of the organism.
Now, another reason that it gets preserved is in these swampy, muddy environments and
as the organisms dies it's tissue breaks down and releases different chemicals.
And some of these are organic acids, and some of them,
there's just a whole suite of different chemicals that come out and
those chemicals radiate away from the body concentrically.
So they start at the body that's decaying and then moves out.
And so we see these chemical reactions that go from
where the actual organism has died and is in the sediments, and moves out away.
And those chemical reactions actually make the sediments,
transition chemically into becoming a solid rock.
And so the solid rocks that we have that preserve these, we call them Concretions.
They look like small eggs but they're kind of flattened and so
these flattened egg-like structures are very common in coal swamp
areas around the world, and again, especially here in the state of Illinois.
If you take those concretions and you put them outside in the wintertime and
then put them outside in the summertime, let them heat up to high temperatures
naturally in the summer, freeze down the cool temperatures in the winter.
They're actually naturally crack open and the crack open along that flat part
of the flattened egg, and it pops into two pieces, and you open it up, and
inside is a beautifully preserved organism.
One of them is the Tully monster.
But everything that lived in the coal swamps
were also preserved in this fashion.
So the concretions have given us a fantastic fossil record of butterflies,
where individual patterns and beautiful shapes of the scales on the leaves,
they're all perfectly preserved down to a single cell level.
We have plant material that looks like it was growing yesterday.
Perfectly preserved in this.
And another great example is the Tully monster.
So, the Paleozoic was diversification at a level that the planet hadn't seen before.
It involved not only the invertebrates, but
then the simultaneous evolution of the vertebrates.
And it included great success in marine environments,
but then full on invasion of the terrestrial land environments.
And those are the characteristics of the Paleozoic fauna.
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