Around 450 million years ago, we have the first plants that
in the fossil record that made it onto land, and
Cooksonia here is the earliest vascular plant from the mid-Silurian.
Here's a view of one of the, one of the Silurian plants under electron
microscope and you can see the branching aspects to it.
As we zoom in, we see the surface of this stalk and
what we see is the epithelial guard cells that protect.
And if we look more closely at the surface,
we see what are very representative of epithelial guard cells,
and these guard cells open and close the stoma.
And this stoma is the opening that allows gases into the plant.
So, water vapor and carbon dioxide go in, oxygen is, is expelled.
And these guard cells will open and
close depending on the amount of water vapor in the environment.
In dry situations, the stoma closes and prevents water from being leaked out.
In relatively moist situations, the stoma open and allows the water in.
Also during this time, we see spores,
which is how these Cooksonia were believed to have reproduced.
And so, if we look at what this environment may have looked like,
the Earth would have been relatively barren.
But we would see occasionally these
Cooksonia that had taken over and colonized the land.
So, if we were able to take a time machine back 300 million years ago into
the Carboniferous, we would see an Earth that looked reasonably similar to today.
We would see seeded plants and forests.
We would see a large range of animals that we see today, insects, crabs,
fish, sharks and amphibians.
So, what has happened during this time as more and
more plants now have colonized the planet is that the amount of oxygen
begins to increase and these forests became quite thick, quite abundant.
And part of the reason that it's called the Carboniferous is because this was
a period where a lot of coal beds were laid down,
a lot, coal being rich in carbon.
This increasing oxygen also caused problems from
the perspective of lightning.
Have lightning started forest fires there in the high oxygen concentration,
these forest fires would have raged out of control.
And indeed, we see an increase in
the amount of forest fires fossilized in the geologic record.
Prof. David M. SchultzProfessor of Synoptic Meteorology
Dr Rochelle TaylorPostdoctoral Research Associate
Dr Jonathan FairmanPostdoctoral Research Associate
