Okay, let's get into this. I want you to picture
something for a second. You're holding a piece
of rock. It's dark. It's from the Australian
bush. And right there in the middle, there's
this brilliant white shape of a leaf. It's an
incredible image. And it's perfect. I mean, you
can see every detail. It's been locked in that
stone for about, what, 150 million years. And
usually, you know, finding something that well
-preserved is a win. You think, great, we know
exactly what this is. Right. Case closed. We
have the evidence. We have the photo. But this
is where it starts to get really interesting.
Because that rock, that perfect impression, it's
a trap. It's a trap that paleontologists have
been falling into for, well, over 100 years.
Just because you have the body doesn't mean you
know who the victim is. And that is the perfect
setup for today's deep dive. We're looking at
a botanical mystery. A species with a... I guess,
a massive identity crisis. That's a good way
to put it. It's a tree that's been dug up, named,
then renamed, and then, well, questioned all
over again. It can't seem to decide what it is.
And it's such a fascinating window into how science
actually works. You know, we think it's a straight
line, but it's often a zigzag. We're looking
at the records around a species called Agathys
juraska. Or, depending on when your textbook
was printed, Potosamites, Jurassic. I love that.
We have to use air quotes around a tree's name.
So our mission today is to figure out how this
one plant can tell us about ancient clivates,
volcanoes, and why just putting a label on something
from the past is so tricky. Exactly. And to do
that, we have to go back. Way back. Okay, so
set the scene for us. Where are we? We're going
to a place called the Talbergar Fishbeds. It's
northwest of Sydney, Australia, out near the
Talbergar River Valley. I think I know the area.
I'm picturing, you know, dry Australian bush,
lots of rocks, maybe forest hills nearby. It's
very stark. Today, yes. But we need to wind the
clock back to the early to middle Jurassic. We're
talking the Tythonian age. Tythonian, okay. When
is that, roughly? About 150 million years ago.
And the world map looks totally different. Australia
is still stuck to Gondwana, the supercontinent.
And this area isn't dry bushland. It's sitting
under the influence of the Tethys Sea. The Talbergar
site itself was actually a large, shallow, freshwater
lake. A lake. Okay, so forget the dust. We're
picturing water. A lot of water and a lot of
life. The sources describe lush, woody vegetation
all around it. Essentially, a dense forest. We'd
probably call it a cowry pine forest. That sounds
nice. So a lake. Ancient pines. And it was teeming.
It's called the fish beds for a reason. Huge
fish populations, insects, and all this diverse
flora along the shoreline. It was a warm, thriving
world. And the atmosphere was different too,
right? More CO2. Much more. And that high carbon
dioxide level acted like a fertilizer, letting
all that vegetation grow incredibly dense and
fast. So we have this Jurassic paradise. Warm,
lush, full of life. But... We're looking at fossils,
and fossils usually mean something went very,
very wrong. They do, and this is where the story
takes a dark turn. The preservation there is
amazing, thousands of specimens, but that's because
of what the sources call a large -scale event.
Which is science -speak for a disaster. A huge
one. The evidence points to the lake being rapidly
inundated with sediment. Volcanic ash, to be
specific. Whoa. So, like a Pompeii, but for fish
and trees. That's a very apt analogy. The ash
came down fast, burying everything. The fish,
the leaves, the branches, it all got trapped.
And that's what preserved them so perfectly.
Exactly. Because it was so fast, and because
of the ash's chemistry, we get what are called
salacious impressions. Salacious impressions.
Break that down for me. Well, normally a leaf
falls, it rots. But the ash sealed it all off
from oxygen. So the organic matter decayed, but
groundwater full of silica seeped in. Silica.
Like in sand or glass. Basically, yeah. The silica
filled in the space where the leaf was, leaving
a perfect, stark white impression on the dark
rock. It's almost like a photograph. It's haunting
this vibrant green world and then, boom, ash.
And everything is frozen in white. It is. But
for scientists, it's a goldmine. It's a snapshot
of exactly what was living there at that very
moment. Which brings us to our mystery plant.
The tree caught in the ash. Right. So let's jump
forward in time. It's 1889. The Talbergar fish
beds are discovered. And I'm guessing the paleontologists
were pretty excited. Oh, absolutely. A guy named
R. Etheridge Jr. publishes the first findings
that same year. And this is where the identity
crisis starts. What did he call our tree? He
identified it as Podosomites lanceolatus. Podosomites
lanceolatus. Sounds official. What does it mean?
Podizomites is a genus of extinct conifers, and
lanceolatus just refers to the lance -shaped
leaves. Long and pointy. So he sees a long, skinny
leaf and says, yep, that's a podizomite. Case
closed. For a while, yeah. I mean, you have to
understand, they were just sorting through thousands
of these things. It's easy to group by what you
see on the surface. Looks like a duck. Quacks
like a duck. Precisely. And in 1921, another
scientist, Walkam, did a more detailed review.
He upheld the name. But he added a little note,
didn't he? He did. He said the flora was likely
coniferous. He was getting close. He knew they
were cone -bearing trees, but he didn't challenge
the name itself. So what was wrong with the name?
Why wasn't it a podosomites? It's all in the
details. The real podosomites has pin -eyed leaflets
that grow from opposite sides of the stem. Think
of it like a feather, sort of symmetrical. Okay,
opposite each other. Got it. But the Talbergar
fossils... They didn't really do that. But for
almost 100 years, nobody really dug into it.
That's amazing. It just sat in the books for
a century. Until. Until 1981. And our detective
arrives, Mary White. Mary White. She does this
intensive review of everything from Talbergar.
And she starts noticing the little things everyone
else had kind of. glossed over. Right. She got
out the magnifying glass, so to speak. She really
did. She saw that the leaf sizes varied along
the smaller branches, which suggested they were
foliage spurs. Foliage spurs. Is that like how
pine needles grow in little bunches? A similar
idea, yes. A specific kind of growth on short
stems. And that is not how porosomites grow.
Uh -huh. There's the tell. And she kept going.
She measured the leaves four to seven centimeters
long, lance -shaped. And she looked at their
arrangement. The arrangement, right. You said
podosomites were opposite. And these weren't.
Mary White saw they had a spiral phyllotaxy.
They grew in a spiral around the stem. Okay,
totally different structure. Completely. Plus,
she looked at the veins. Parallel veins, about
five to eight per leaf. Wow, that's specific.
It has to be. But the real kicker. It wasn't
just the leaves, it was the cones. The reproductive
parts. Exactly. For decades, the cones found
at the site were classified as a totally separate
species, something called Orocarites grandus.
So they thought they were just two different
plants mixed together. Yes. But Mary White looked
at these cylindrical cones and realized, wait
a minute, these... These belong to the leaves.
She put them together. That's a huge connection,
connecting the fruit to the tree. It was. And
with the spiral leaves, the foliage spurs, and
now the cones, she concluded it was much closer
to the modern genus Agathys. Agathys. Okay, for
those of us who aren't botanists, what is that?
Think of the giant cowry pines in New Zealand
and Australia. These massive ancient conifers,
giants of the forest. So she's saying this Jurassic
fossil isn't some random extinct plant. It's
a direct ancestor of the modern cowrie. That's
exactly what she's saying. And she renames it
Agathys Jurassic. Agathys Jurassic. It has a
good ring to it. And that feels like a big moment.
Yeah. You're tracing this modern giant all the
way back to the age of dinosaurs. It was a massive
aha moment. It rewrote the evolutionary history
of that whole forest. It meant the cowrie pines
were incredibly ancient survivors. I can hear
the butt in your voice. There's always a butt.
There is always a but. This is where it gets
good. You'd think, okay, 1981, she does the work,
case closed, we have our name. You'd think. But
science is skeptical. Fast forward to 1999. Two
researchers, Hill and Broderib, are reviewing
the whole fossil family, Arachariaceae. That's
the family these trees belong in. Yes. And they
hit a snag, a chronological snag. What do you
mean? They looked at the whole fossil record
globally, and they noticed that the oldest...
The most reliably identified Agathys fossils,
the ones everyone agrees on, are from the Middle
Eocene. The Eocene. Okay. How far is that from
the Jurassic? It's a huge gap. The Jurassic is
about 150 million years ago. The Middle Eocene
is more like 40, maybe 50 million years ago.
Oh. That's a hundred million year gap in the
fossil record. It's enormous. It's a huge problem.
If this thing from the Jurassic really is Agathys,
where are all its descendants for the next hundred
million years? There's just nothing. It's like
finding a Roman chariot and then a brand new
Ferrari and saying one led directly to the other
with no cars in between. That's a great way to
put it. You need the intermediate steps. Without
them, it's just a wild coincidence. So what do
they do? Do they just say Mary White was wrong?
Well, they cast major doubt on it. They said,
you know, the visual match is there, but the
timeline just doesn't work. It's suspicious.
So they took the name away again. Not officially,
but because of their work, other scientists started
calling it Podosomite's Jurassic. It swung back.
Unbelievable. The poor tree is just getting tossed
back and forth. It gets even messier. As of 2017,
the name Podosomites jurassica hadn't even been
validly published. What does that mean? In taxonomy,
there are strict rules for naming a species.
You have to follow a process. And no one had
actually done the official paperwork to make
that name stick. So it's in taxonomic limbo.
Completely. It's not the original podozomites.
It might be Agathys, but the timeline is a huge
problem. And it might be a new kind of podozomites,
but nobody's officially named it that way. That
is just, it's absurd. We have thousands of perfect
fossils. But we can't agree on what to call them.
And it matters. It's a really important debate
about ancestry. Is this a direct grandfather
of modern Kairi Pines? Or is it just a distant
cousin that evolved to look very similar and
then went extinct? Convergent evolution. Exactly.
Like a shark and a dolphin. They look similar,
but they're not closely related at all. If this
is a lookalike, then the carapine is a much younger
species than Mary White thought. And what about
its range? It was mostly an Australian thing?
Primarily southern hemisphere, yes. This was
Gondwana, remember. But the sources do mention
some marginal expanses into the northern hemisphere.
It's a southern specialist, then. It seems so,
yeah. Adapted to that warm, high CO2 world. Okay,
so let's recap this whole journey. We start...
In a Jurassic forest. A forest that gets flash
frozen by volcanic ash. We dig it up in 1889
and call it Podosomites. Then in 1981, Mary White
sees the spiral leaves and calls it Agathys.
And then the timeline police show up in 1999,
point out the 100 million year gap, and push
it back towards Podosomites. Where it sits today,
kind of nameless. It just goes to show you that
science isn't this neat collection of facts,
it's an argument. A long, slow argument. It is.
And that's what's so cool. The rock itself hasn't
changed. The fossil is the same. But our understanding,
our framework for interpreting it keeps shifting.
And I think that's what's so fun about these
deep dives. You realize even something as solid
as a rock is. It's up for debate. Absolutely.
And it's a good reminder to be humble. We're
looking at a shadow of the past, literally, and
trying to build an entire history from it. So
I guess the takeaway for you listening is next
time you see a pine tree, you can wonder, is
its family tree 50 million years old or 150 million?
And are there ghosts in that tree we just haven't
found the right name for yet? Exactly. I want
to leave you with a final thought on this. We
talked about those stark white impressions. The
ash preserved the shape. Nature's own photograph.
It is. But think about it this way. We have the
photograph. It's perfectly clear. But we are
still fighting over the caption underneath it.
If Mary White was right, if it is Agathys, that
means that genus survived the asteroid that killed
the dinosaurs. It survived the breakup of Gondwana.
It survived ice ages. It would be one of the
planet's ultimate survivors. And if she was wrong.
If she was wrong. Yeah. Then that Jurassic forest
at Talbogar was filled with some other kind of
giant that just happened to look exactly like
a cowry pine and then vanished completely. So
what was that tree? The rock shows us the what,
but it just refuses to tell us the who. And that's
the mystery that keeps us digging. And that's
where we'll leave it. Thanks for diving deep
with us into the identity crisis of Agathys,
Jurassic. My pleasure. Always fun. See you next
time.