Okay the talk today is about what I've entitled Australia's Green History and it's looking at the
history of vegetation and the Australian flora over time. The talk is really going to focus
on three kind of key questions which is how do fossil plants get preserved, what parts of plants
get preserved in the fossil record, and why are plants important and why is paleobotany important?
And so when we think of fossil plants we have to think of the conditions in which they're preserved
and often we think of places like swamps, lakes and deposits like this and certainly these are
the right conditions, they're low in oxygen and the leaves sink to the bottom of the lake and they
get covered by fine sediment and if the conditions are right you'll get preservation of the fossils
but you can also get preservation of fossils due to volcanic activity
and so along the eastern coast of Australia we've got lots of evidence of volcanoes and active
episodes of volcanicity in the last 40 to 20 million years
and everybody involved in the cross river tunnel will know that a fossil tree trunk was found
in the cross river tunnel and that was covered up by a volcanic flow at that time 200 million
years ago. What I'll be looking at in this talk is more recently the more recent flora of Australia
and how it evolved. So what kinds of plants can what kind of plant parts can you expect to find
when you're digging in the fossil record and obviously you'll find leaves,
you'll find examples of wood, you'll get evidence of pollen and spores which are the reproductive
parts of the plant and very rarely you'll get flowers and you'll also get seeds and fruits.
So this is one of the leaves we've been working on recently it's from a site up near Mackay
in Central Queensland and it it is a member of the nothogaus family or nothofagus genus
and you can see the serrated margins and the leaves. You can also see there's a bit of insect
damage as well on the leaves as well which makes it quite interesting. The fossil is particularly
exciting because we only find this particular genus of trees on the very tops of mountain ranges
in South East Queensland and here we have it in Central Queensland about 30 million years ago.
But why do why do leaves get preserved? Because they're quite resistant and leaves are designed to
survive for quite a few years on the tree before they actually fall off.
And they've got a layer of cuticle on the leaf that is a thickened layer and that protects the
soft tissue with inside the leaf. And very rarely we find evidence of mummified leaves
and this is an example of some mummified leaves from a site in Victoria and these were found from
the Anglesea coal mine and you can see the actual cuticle of the plant is still preserved so if you
get the right conditions and it doesn't happen very often but if you get the right conditions you
can get whole leaves and flowers being preserved in these low energy lakes and deposits like this
and you very carefully get the leaves out of the sediment by using peroxide or other
chemicals and the leaves will actually float out. So that's a 40 million year old leaf.
One of the things that we often find and as with a cross river tunnel project we found
a tree trunk but you find within modern woods you get different types and you'll see that in the
in the picture up here you can see that there are two different types. One is a conifer wood
and that's on my right hand side and on the left is a flowering plant wood and you can
see how that there are differences in the kinds of cells that you find within the wood so as a
paleobotanist I can actually identify the types of plants from the wood structure that you see.
And you can also see that there's evidence of growth rings as well so that also provides us
information on the climate at the time as well.
Occasionally some woods are so interesting and so well preserved that you can actually identify
which groups of plants they belong to and this particular piece of wood is from a native vine
of the grape family and you can see that there's a bark and there's a soft tissue preserved
along with the heart wood in the center of the of the vine.
Flowers are rarely preserved and there's a reason for that. While leaves are kind of thick and
they've got an impervious cuticle layer, flowers are only designed to last for a day or two days,
they fall off the tree and they're not designed to survive any longer than that
and they're very thin structures. So there's a reason why we don't find many flowers
on the fossil record but we do occasionally get them and this is some drawings of some flowers
from a site near Ipswich at Dinmore and you can see that the petals have got fringes on them
and these features allow us to compare them to other plants that other living plants
that have got fringe petals as well which is this coachwood flower you can see here and the
petals are these weird kind of five five-fingered appendages on them and they're quite distinctive.
We often find is evidence of pollen and spores
now you may not realize this but we know that we suffer from asthma all the time
at certain times of the year and pollen and spores are remarkably resistant and they get preserved in
the fossil record and they can also tell us about the kinds of plants that were living at that time.
And this particular slide shows you some spores of a fern called lygodium which is the climbing fern.
I guess for me some of the most interesting plants parts we find belong to fruits and seeds and these
are some examples here from sites in Central Queensland and they're associated with volcanoes
and volcanicity so they were they were preserved due to volcanic flows at that time and we recently
just in the last couple months described what is the first fossil pandanus known from Australia
this is this is a picture of the fruit here and this is a line drawing of it as well to show
you the appearance and if you aren't sure what pandanus looks like this is a tree that you see
along the coastal along the coast of South East Queensland on the beaches and the surf beaches
it's a really quite beautiful tree. There's one really peculiar thing about this fruit.
And that is its size. It's really really small,
it's really tiny and yet when we compare it to modern pandanus
it's a massive fruit so the question we can't answer the question completely but
we just know that we're fairly certain that is a mature fruit and back 30 million years
ago fruits of this particular genus were much smaller than they are today.
And thanks to a colleague at the museum we recently did a reconstruction of what this
fossil plant might have looked like so this is the first time we've shown this flower, this
illustration to anybody. So 30 million years ago is when these fossil pandanus fruits and
and the other seeds I mentioned were found and at this time Australia was moving northwards towards
South East Asia which separated from Antarctica and ice was forming in Antarctica at that time
so Australia wasn't was a raft, it was an isolated raft moving northwards away from
Antarctica. I want to show you now some footage to show you the kind of new techniques that we're
applying in the study of paleobotany and this is some work i did with colleagues Anita Milroy
and others and it looks using synchrotron data it helps us look at the internal morphology of
a fossil fruit that was collected from the same volcanic site in Queensland
and this is the fruit here you can see the external morphology and as the synchrotron imaging
is shown you're getting a view of the external appearance you're getting a view of the external
structures on the outside of the fruit but we now begin to look into the internal structure and we
can see the internal anatomy of the fruit and you can just begin to see that the ovules are there
and you're beginning to see the internal structure and the
vascular tissue that leads to the ovules and things like that.
So why are plants important? Well all life on this planet and all terrestrial life on this planet
is only possible because we have plants. So all insect life or dinosaurs all the animals that
we associate with paleontology are invariably associated only here because we have plants.
I guess the reason why I study fossils, the reason why I'm so excited by this area is
that fossils help us explore and understand the origins and the history of life in Australia and
the origins of the Australian flora and fauna and Queensland Museum scientists have been working in
this space now for over 100 years. And we've been recently doing some work and described the first
sea scorpion known from Queensland which is the animal you see here and of course none of this
work is done without help from colleagues and I'd like to acknowledge the different people who
have contributed to this particular project over the last five to ten years. Thank you so much.
you