Summary:
Did the birds come from dinosaurs?
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Student: Many people believe that today's birds are the evolved dinosaurs from the past. Is that true?
Robert: Yes, now it's commonly accepted that birds actually evolved from a group of dinosaurs, but way back in the Triassic probably, or in the Jurassic. The first uncontested bird fossil
is called Archaeopteryx, comes from the Jurassic in Germany, and there are a lot more bird fossils have been found in the last ten to twenty years, particularly from China.
And we have dinosaurs now from places like in China that actually have, they are definitely dinosaurs and they have feathers and we have birds again with feathers.
And the line between, the distinction between dinosaurs and birds, is getting harder to define now, as you can see, these basically intermediate forms coming.
So it's pretty well accepted that birds did evolve from dinosaurs so that is one group of dinosaurs that didn't become extinct at the end of the Cretaceous and so they're living with us now.
So when you go and have your Kentucky Fried Chicken or you're eating a chicken or something like that, you're actually eating a dinosaur.
Student: Do you think that since birds lay eggs, do all dinosaurs lay eggs as well or some were born alive?
Robert: There is only evidence for dinosaurs laying eggs. Dinosaurs were terrestrial creatures, that is, they lived on the land.
So it's best if they can lay eggs, they make nests and lay their eggs in it. But there were other creatures that lived at the same time as the dinosaurs that were reptiles.
Particularly reptiles that lived in the sea, one called an Ichthyosaur, and it's been shown to produce live young
because they have actually got some fossils of Ichthyosaurs, from a place in Germany where you can see the embryos inside a mother and also ones that have just been born.
It's quite amazing to see these fossils with little baby Ichthyosaurs that have just been born. So there were some groups of reptiles that produced live young but dinosaurs, no, laid eggs.
Student: But they weren't classified as dinosaurs.
Robert: They are not actually dinosaurs, no, dinosaurs are terrestrial, they always had four legs, whether they actually ran on two legs or four legs but they only walked on the land,
they didn't have fins or flippers, that sort of thing, or didn't fly in the air. The ones that flew in the air weren't dinosaurs, those are pterosaurs:
related to the dinosaurs but they are not defined as dinosaurs.
Summary:
Why did Tyrannosaurus have such stumpy arms?
Were all dinosaurs carnivorous?
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Student 1: Why did the Tyrannosaurus rex have such stumpy arms, that would have looked like they were useless?
Robert: Right, yes, they did look very useless, the front arms of the Tyrannosaurus rex and there is has been a bit of debate on why it did have these small, two-fingered arms.
I don't think it's been definitely worked out why. There could be various reasons; it couldn't reach into its mouth so it couldn't actually hold anything or grasp anything with it.
Maybe, it was to do with its balance; the centre of gravity. If it had large arms it could fall over more easily, I don't know. And obviously, it was designed to catch things using only its jaws.
It had very massive, as you can see the skull of Tyrannosaurus rex, was very massive, so it just used its jaws to catch things.
Other carnivorous dinosaurs similar to Tyrannosaurus rex that had long arms, often had more lightly built jaws.
So they used their front arms, the other ones, to actually grab things. So Tyrannosaurus rex didn't have to do this but why,
we don't exactly know and the research and debate about this, is ongoing.
Student 2: Why were all dinosaurs carnivores?
Robert: Well, not all dinosaurs are carnivores. A group of dinosaurs are carnivores and a large proportion of dinosaurs are actually herbivores.
You need to have herbivores to feed the carnivores and you need more herbivores to feed the carnivores than you actually need carnivores.
So you'll have a small proportion of carnivorous dinosaurs like Tyrannosaurus, Allosaurus and Giganotosaurus ...
but you will have a lot larger number of herbivorous dinosaurs like the sauropods or the ornithopods. There is a larger range of herbivorous dinosaurs than there are carnivorous dinosaurs.
Summary:
What are the rules for collecting fossils?
How difficult is it to reconstruct a skeleton?
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Student: What are the rules about collecting fossils yourself?
Robert: There's no specific legislation in New South Wales about collecting fossils.
If you go out onto the land and find some fossils you basically, if you find them with permission of the landowner, you can keep them.
If you find them on what we call crown land or like government-owned land, generally you can keep those as long as you haven't actually excavated using machinery.
So as what they basically call fossicking, you've just dug up by hand and haven't dug a huge quarry to find.
And of course in national parks you aren't allowed to touch fossils, you can only look.
So, really it's up to you if you find fossils you can basically keep them, as I say, as long as you have permission to be on that land or permission of the landowner to keep those fossils.
Student: What are certain problems you face when reconstructing partial skeletons?
Robert: Well, when you only have parts of the skeleton you have to know obviously what goes where.
You know what goes where from comparative anatomy, basically experience and studying comparative anatomy.
You know what bones go where in other animals, like as in whole animals, as in live animals.
So, since dinosaurs are basically set out the same way as all vertebrates,
we can see and determine what a bone is by just comparing it with other bones and through our knowledge of what goes where.
So, it's just basically knowledge and experience and using comparative anatomy that we can use to reconstruct a skeleton of any animal really.
Summary:
What are the tools of a palaeontologist?
What is the process of transporting fossils, and what happens back at the museum?
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Student: What kinds of tools do you use for the initial extraction of a fossil?
Robert: That would vary; depends on how much material you have to move. You might want to use mechanical tools and excavators to remove the overburden that might be over some fossils.
As you work further down I suppose you get down to using things like hand tools such as shovels, picks and spades
and then going down finer and finer you start to use smaller hand tools like these. We use hammers, which is a pick as well.
You might want to use a chisel with your hammer so you chisel away with a cold chisel and then brushes for cleaning up the chips away and so expose your fossil.
Getting down to fine, very fine detailed work, we use this thing called a pin vice which is actually just a pin held in a hand piece
so then you can pick out and flick out little bits of rock to clean up your fossil.
Student: How do you prepare the specimen for the travel?
Robert: When we excavate fossils out in the field we have to protect them to bring them back to the laboratories, so the best way to do that is to encase it in, you know, what we call a plaster jacket.
So, what we do, a plaster jacket is just like you get around a broken leg or a broken arm so you wrap it up in plaster.
So we uncover our top surface and then cover it up with strips of hessian which have been dipped in plaster until it gets to the required sort of thickness.
We then sort of flip it over, clean off the underside and cover up that side.
So, you end up with a nice, neat parcel that's been jacketed in this plaster, so that is the way that it's protected to bring it back to the laboratory.
Student: What is the process back at the museum?
Robert: When we get it back to the laboratory and the museum we first have to open up the jacket.
That can be quite difficult because, you know, we've usually made them pretty sort of robust things but we have to cut around the jacket,
take the top off and usually you leave one side of the jacket on to support the fossil while we're doing this.
Then start to clean off all the rocks, so get off all the excess rock off, often with fine tools like the pin vice I showed you earlier,
dental tools, and to just slowly pick away the rock and eventually you can excavate right around the bone and free the bone completely and pull the bone out.
So, this is the process back in the laboratory. Sometimes you'll find that the bone might be fragile,
it has to be hardened using some plastic solutions and things like that or it can be actually broken and they have to glue it back together.
So, this is the sort of work we can have to do back at the laboratory.
Summary:
How can you tell the lifestyle of a fossil from a bone?
What machinery is used to uncover fossils?
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Student: Can you talk about how we know the lifestyle and physical capacities of some dinosaurs when all we have is bones?
Robert: You can sort of work out what a dinosaur looked like by having enough bones and using comparative anatomy to work out what it actually was totally like.
And from this, you can see four-legged, two-legged, from the teeth you can tell what it ate.
You might want to also look at other things you find in the rock nearby, other fossils in the rock, small things like pollen, to work out what vegetation was round about it.
From that it might help you work out what it ate. There are other clues in the rocks too, that can tell you what maybe the temperature was like at the time.
They can work out temperatures using oxygen isotope ratios and you can see the evidence of ice and such things as this.
And there is a whole lot of clues you can gather from the fossil itself and from the surrounding sediments that tell you what the habitat was like the dinosaur lived in.
Student: Can you tell me what type of machinery you use to uncover these findings?
Robert: Out in the field, it's just excavation-type machinery I suppose, and that can vary from just using backhoe or an excavator, even to using explosives to help you extract fossils.
Explosives, you've got to be very careful with explosives for two reasons: because they're dangerous and also they tend to break things up into small pieces.
But these can be used to advantage to extract fossils.
Summary:
Why are complete fossils so rare?
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Student: How come fully complete dinosaur fossil skeletons are so rare?
Robert: Well, fossils form after an animal dies.
To have a fossil formed though you need certain conditions and the conditions are that they get covered up and preserved quickly.
If it's not covered up and preserved quickly it rots and then tends to fall apart.
And of course the bones are the hardest part and so they're going to remain for a lot longer than the soft parts.
But what can happen when it rots away is the bones can then get disarticulated and distributed around the place so they can get washed away.
So it's unlikely that you're going to get a whole dinosaur preserved because, as I say, it's got to happen very quickly
that you get the dinosaur covered up by sediment to preserve everything intact.
This does happen though and occasionally you will find that dinosaurs are nearly complete,
some rarely totally complete dinosaur fossils are found but, yeah, it does occur often enough to know what quite a few dinosaurs looked like just from finding their skeletons.
We don't have to and we don't have to actually sort of guess too much or use comparative anatomy because it's all there in front of us.
But other cases that I could have mentioned before you can find just one bone and often from one bone you can work out what the dinosaur might have looked like.
Summary:
How much is a fossil worth?
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Student: About how much are dinosaurs worth, like, their fossils?
Robert: Commercially, dinosaurs have been worth quite a bit but really scientifically they're invaluable.
They're priceless scientific specimens and, to me, that's what concerns me the most, they're scientific specimens.
I don't like to see dinosaurs actually sold for money because it makes them a lot more difficult for us to get hold of.
But auctions of dinosaurs, especially complete dinosaurs, can bring millions of dollars if they are actual specimens and they are complete.
But scientifically they are priceless and that's what we are most concerned about.
Student: Thank you, Robert, for having us and telling us about dinosaurs and their fossils.
Robert: You're most welcome. I'm glad you could come along.
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