Marine Fossils- Oceanfront Property in New
Mexico?
[music]
Liliarosa Salmon: Welcome back to another
episode of Traces of the Lost World.
Today we are at little Apache Dam in the Robledo
Mountains, and we are talking to Spencer Lucas
about how we come to see all of these marine
fossils and what is the connection to being
able to see marine fossils and trackways.
Spencer Lucas: Right.
OK, I'm Spencer Lucas.
I'm the Curator of Paleontology at the New
Mexico Museum of Natural History in Albuquerque.
Here, at this location in the Robledo Mountains,
we're standing on limestone beds, layers of
limestone that are just full of fossil shells.
One of the interesting things about this whole
area is, we not only get the footprints, which
are the trace fossils of animals that were
living on land, but we also get the shells
of the types of animals that were living in
the shallow sea that covered this part of
New Mexico 280 million years ago.
When we look at these layers as geologists
or paleontologists, what we see, amazingly
since we're here in the desert now, is evidence
that a warm, shallow sea, much like the Caribbean
Ocean today, was covering this area hundreds
of millions of years ago.
When we look at the limestones themselves,
the best evidence that the sea was here is
in the shells of the fossils that we find.
Because the kinds of animals that we see here
preserved are animals like clams and snails
and then a type of animal that most people
don't know, brachiopods.
They're kind of clam like.
But these are animals that live today in the
sea.
And so, when we see their fossils in the rocks,
we can make that strong connection.
It's one of the great principles of geology
that the present is the key to the past.
So we look at the present day animals and
where they live, and then we look at their
past, their extinct relatives that we find
as fossils.
And we're able to be very certain that there
was a sea here, and these shells preserve
evidence of that sea.
Liliarosa Salmon: We would be under water
if we had been here how long ago?
Spencer: If we had been here in the early
Permian, 280 million years ago, we would have
been under water.
We would have been probably at least a 100
feet under water...
Liliarosa Salmon: [chuckles]
Spencer: ...to get to this sea bottom.
But this would have been a lot like if you've
gone anywhere in the Caribbean or you've gone
to Florida and you've gone Snorkeling.
You would snorkel around.
These would have been very clear waters, very
warm waters.
They would have been sunlit bottoms and shallow
water.
It would have been just a wonderful place
to be.
There would have also even been sharks living
here, because we have found sharks' teeth
in these limestones.
So there would have been some dangerous animals...
Liliarosa Salmon: [chuckles]
Spencer: ...but it wouldn't have been any
more dangerous, probably, than it is today
to swim in such a shallow sea.
Liliarosa Salmon: We get to see both plant
and animal remains or prints in this limestones
here?
Spencer: Well now, in the limestones, really...
well, we see some plants.
We see some algae that were living under the
sea.
But we have to go up the hill behind us here
to get to the red layers that were formed
on land, and they have the tracks and the
leaves and the plant fossils in them.
Here we're definitely in the sea.
Liliarosa Salmon: OK.
[background noise, off mic conversation]
Spencer: Well this is a really unusual fossil
here.
Probably some of the biggest animals that
swam in the sea are animals, we call them
cephalopods.
They're the extinct relatives of living squid
and octopuses.
This thing was a big nautiloid.
It's only part of the shell.
This thing would have had a huge tube like
shell.
It's been broken open, and you're only seeing
one side of it preserved here in the rock.
So we not only see the fossils of animals
that actually lived on the sea bottom, like
the clams and the snails, but we also see
the fossils of animals that were swimming
in the water column above the sea.
When they died, their shells would sink down
to the bottom and get fossilized here.
This would have been an animal that would
have been swimming in the water column that
was a hunting type of animal.
It was a predator.
It would have been swimming around looking
for its prey items, probably mostly eating
things that lived on the sea bottom, as do
modern squid today.
What always amazes me when I see these shell
beds, is just to think about how much biological
productivity, how much life there was here,
and now it's all gone.
This represents, if you were just thinking
of it as seafood, as something you would eat
at a seafood restaurant, there's just a tremendous
amount of biological material in all these
shells.
There was a lot of life here.
This was a good place to live during the Permian.
It was a really rich environment.
We're looking here at a sea bottom, and we
have a remarkable amount of diversity with
many, many different kinds of shells and parts
of shells.
This isn't surprising to see, because we know
that these sea bottoms were in the tropical
latitudes at the time the rocks were formed.
We know today that when we go to the tropics
we see higher diversity than we see outside
of the tropics.
This fits, a kind of again, that present is
the key to the past.
There were a tremendous number of species
living on the sea floor.
That's what we mean by diversity, just the
number of kinds of animals that were living
here.
In a tropical sea like this 280 million years
ago, we see high diversity, which is something
we see today in tropical seas.
That tells us that, whatever is driving diversity,
whatever causes high diversity has been doing
it for hundreds of millions of years.
So if we want to understand diversity, we
have to explain it as something that we know
has been going on for many hundreds of millions
of years, just like diversity is today.
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Transcription by CastingWords
