Dinosaurs and other creatures
Video | Updated 9 months ago
As part of the In the Wild West lecture series, Dr Mikael Siversson, Curator of Palaeontology delivered his talk Dinosaurs and other creatures.
Dinosaurs reached their peak diversity during the Cretaceous period when the rising sea isolated animal populations on large islands. This era produced some of the most spectacular animals the world has ever seen.
Join Dr Mikael Siversson as he presents a time in our planet’s history when giant dinosaurs walked the earth, plane-sized pterosaurs patrolled the skies, and enormous crocodilians lurked in the rivers.
Rangelands Natural Resource Management is the Presenting Partner of the 2014 In the Wild West series.
Mikael Siversson: Well thank you for coming and listening to my talk today about dinosaurs and some of the other creatures that lived during the Cretaceous period. I'm going to talk about not only dinosaurs but other creatures and from Australia and overseas, and also what we palaeontologists do when we go out in the field looking for these creatures.
Sixty-six million years ago something really bad happened to our planet. A huge asteroid or possibly a big comet slammed into our planet and as a result there was a huge dust cloud thrown into the atmosphere that spread all the way around the globe and sunlight was largely blocked out for maybe up to ten years. You can imagine the effect that had on plants initially and then on anything that sustained themselves on plants.
As a result the plant-eating dinosaurs died out and the meat-eating dinosaurs of course, they starved to death. Not only were the dinosaurs affected, but many other groups. About half of all the species of fish in the oceans went extinct. The flying reptiles – the pterosaurs – went extinct and many groups were really hit very hard.
The Cretaceous greenhouse world … that's often a term you hear when you listen about the Cretaceous. The Cretaceous is the last, the third stage of the three periods that commonly is known as ‘the age of the dinosaurs’ – we have the Triassic - 250 to 200 million years, then the Jurassic period – up until 145 million years ago and then Cretaceous – from 145 to 66 million years ago. So why is it called the greenhouse world?
Well, if you have a greenhouse and you're really serious about it, if you want to maximise the size of your vegetables and shorten the time it takes for them – you know – ready to be harvested, one thing you do is you crank up the carbon dioxide. You elevate the carbon dioxide in the greenhouse to about 1,500 parts per million. Today we have about 400 parts per million and 1,500 parts per million is approximately though, the CO2 levels we had during the middle part of the Cretaceous period.
Now, one thing about the age of the dinosaurs, … many of these dinosaurs were very, very large. Now how come they could grow to such an enormous size? It could be that the … it could be related to the very high levels of CO2 because when you crank it up in a greenhouse, plants will grow faster. So, that might explain why some of these dinosaurs were so large … more food for the plant-eating dinosaurs.
If we go back in time, let's say 100 million years ago, the planet was very different. It was much warmer than it is today and the carbon dioxide levels were very, very high. It is probable also that the oxygen levels were much higher as well because if plants grow faster and green algae in the water grow faster, as a by-product of the photosynthesis, they'll produce more oxygen. So the oxygen level rises. So for example, if there was a wildfire during the Cretaceous period, it's likely that it was more intense than it would have been today. So where did all this carbon dioxide come from?
It came from volcanic activity. The globe is made up of about 12 big plates and a number of smaller plates and these plates, they move around relative to each other all the time. Australia for example, we are heading north by about 5 or 10 centimetres per year - it's a slow but steady process - and at times during the history of our planet the average velocity of these plates might have been higher or lower. When they speed up which seems to have been the case during the Cretaceous period, you will get more volcanism simply. So that's why we had higher levels, or that's why we believe we had higher levels of carbon dioxide during the Cretaceous period.
Now one of the effects of [carbon dioxide] being a greenhouse gas, is that it raised the temperature. So we got a major sea level rise. When you raise the temperature water will get warmer and it will expand in itself, but also if you have a lot of volcanism on the sea floor, there is going to be a lot of new, what we call oceanic crust and it takes a while for that to cool down and contract. So it's going to be quite fluffy and have a larger volume, so that helped pushing up the water onto the continents. So during the middle Cretaceous sea levels might have been as much as 150 metres higher than they are today. So the continents were highly fragmented, leaving many of these dinosaur populations isolated.
Here we have a graph showing the climate and the temperature over the last 500 million years and we can see during the Cretaceous period, especially during the middle Cretaceous, it was very, very warm compared to today when we have … we are sort of still in an ice age period geologically speaking. The last time we had an ice age was during the Carboniferous /Permian boundary here when we had huge ice sheets on Gondwana, the ancient supercontinent.
I'm not sure if any of you have seen there's a dinosaur movie – I saw it going up to Karratha just a few days ago – Walking with Dinosaurs. Anyway, that took place here along the eastern shore of Laramidia which was a large island that formed in North America. You can see how high the sea level was during the Cretaceous period. So North America turned into a fragmented [place], almost like an archipelago. Europe certainly formed an archipelago during the late Cretaceous.
That's just setting the scene. So we have very high sea levels, not much land exposed. Today it’s about 29% [of the earth’s surface]. During the mid Cretaceous 19% was land, the rest was ocean. But one of the most interesting aspects of working on dinosaurs is how we relate birds to dinosaurs. If you read a scientific publication published let's say, 40 years ago – here is one published in the American Naturalist. It says "Giant dinosaurs dominated the Mesozoic era." It's quite clear-cut. If you read a modern paper like this one published by palaeontologists, including Australian palaeontologists, "A critical reassessment of the Cretaceous non-avian dinosaur faunas..." What's a non-avian dinosaur? If there are non-avian dinosaurs, that implies there must be avian dinosaurs.
There is an avian dinosaur. Ever since about twenty, thirty years ago – especially over the last two decades – palaeontologists working on dinosaurs, they all regard birds not only as closely related to dinosaurs, but as one of different dinosaur groups. So they talk about tyrannosaurs as one group, the horned Triceratops types is another one. You have the sauropods and you have the birds. So birds are essentially dinosaurs … and how do we know that?
I'm sure you've seen – most of you would have seen and possibly all of you have seen – the Jurassic Park movies. [Addresses screen] Now this is how Velociraptor was portrayed. He's a very vicious animal as you can see, that huge claw they had on the second toe, but the skin is very reptile-like. However, that turns out to be all wrong, and how do we know that? Well over the last 20 odd years there's been absolutely fantastic dinosaur fossils being found in China in ancient lakes, a system of lakes in eastern China that formed around 120 million years ago.
Now these lakes were surrounded by plenty of volcanoes and at times there was a major volcanic eruption, a lot of ash-fall and dinosaurs died and drowned if they walked near the lake. And that very fine ash cloud would preserve these dinosaurs in great details, and it turns out that all the raptor dinosaurs that have been found in these Chinese deposits, they're well enough preserved, they all have feathers. Every one of them has feathers. They have feathers on their arms and some even had feathers on their legs and some of them could sort of glide from one tree to another, very, very bird like. And other features that were thought to be unique to birds is the wishbone for example, but even T-rex has a wishbone. So many of these characteristics, .. one-by-one, they've been shown to be widespread among the meat-eating dinosaurs.
[Addresses screen] Look at that big, massive claw on the finger. This is the Latin genus name of that creature. Anyone can figure out what finger this belongs to that has such a big, whopping claw? There’s an emu. Did you know emus have claws bigger than a cat? Next time if you sadly enough come across a dead emu, check out the fingers … and emus belong to a group of birds that are the closest living relatives to the non-avian dinosaurs.
Here's another fantastic fossil coming out from China, Microraptor. That's the smallest raptor dinosaur and you can see big feathers, both on its arms and its legs. Not only do we know that these raptors had feathers, we also know in many cases what colour they had. How do we know that? Well it turns out when we put the feathers under a high powered microscope, we could see that the pigmentation cells were still preserved. So Microraptor for example, we know it was blue-blackish and some of the other raptor dinosaurs had bright red, all sorts of colours, just like modern birds or avian dinosaurs I'll call them.
During the age of the dinosaurs, from Triassic all the way to the end of the Cretaceous, there were mammals around as well. Certainly when you get into the Jurassic-Cretaceous, they're what we call proper mammals, but one feature about these mammals is they were all tiny during this, what we call the age of the dinosaurs. The biggest might have been the size of a Tasmanian devil, but most of them were as big as a mouse or a rat and that indicates that there was a tremendous predation pressure on these mammals. Once they reached a certain size, they were just picked off maybe by the raptor dinosaurs. So there must have been something that gave the meat-eating dinosaurs a competitive advantage over the mammals. Now what could that have been? One can only speculate.
If you look at birds' lungs for example, they are very different from those of the mammals. We have squishy lungs, so we inhale, the air goes in and when we breathe out it goes out again, whereas birds they have very stiff lungs and then they have a set of huge air sacs. So when they breathe in the air goes to the back end of the body into big air sacs and then it's squished through the lungs into another set of air sacs and then the air goes out. So the air is a one-way system. It's a far more effective system of extracting oxygen, and birds, they need a lot of oxygen when they fly. We think that the dinosaurs had the same type of very effective lungs and that could explain perhaps why they had this tremendous advantage over the mammals. So imagine these Velociraptor dinosaurs for example, … these vicious animals with enormous stamina. That would be the scariest thing if you were a little mammal.
[Addresses screen] Here is the illustration of the North American equivalent of Velociraptor. Sauronitholestes has caught one of these poor little mammals. The mammals probably were nocturnal, so they were probably out during the dark and we can see some of the small plant-eating dinosaurs were probably also nocturnal and they dug burrows because they had big eyes, indicating they were active mostly at night.
So this is how we actually classify dinosaurs these days. You have the ornithischian dinosaurs which are all plant-eating and these are all the saurichian dinosaurs. You can see here the birds are deeply nested within the dinosaur tree. So it's not a group separate from the dinosaurs. They are present here deep within the dinosaur. So birds are essentially dinosaurs.
Now when I give talks, people in general they tend to be very interested about dinosaurs, especially the meat-eating dinosaurs. I'm just going to mention a little bit about some of these, what do you call them, the theropods, the meat-eating dinosaurs.
[Addresses screen] Now this is the biggest of all the meat-eating dinosaurs, Spinosaurus … and I presume most of you have already seen our animatronics Spinosaurus which is a life-size 14 metres long. The interesting thing about Spinosaurus is that it was actually a fish-eater. The jaws had the same shape as those of a crocodile, especially the strictly fish-eating crocodiles and of course it has this huge sail here that we are not quite sure what they used it for, maybe to regulate its body heat or maybe it acted as a support for a build-up of fat that they could use during starvation. That's possible.
Spinosaurus could grow to maybe 12, 13, 14 possibly 15 metres in length and Carcharodontosaurus which lived in the same area Northern Africa 100 million years ago was very similar in size. This looks very much like a T-rex but it's not closely related to the tyrannosaurs. The tyrannosaurs, they were still around at this time, but they were quite small, maybe just a couple of metres tall, but once the big Carcharodontosaurus and the spinosaurs went extinct, the tyrannosaurs started to increase in size, … [addresses screen] and here we have the skull of a T-rex. So all these three types, you have the spinosaurids, the Carcharodontosaurus of the mid Cretaceous and then the late Cretaceous tyrannosaur, they all seem to be about the same size. That seems to be the practical upper limit for these meat-eating dinosaurs, around 12 to maybe 14 metres.
So how come we don't have a 28 metre tyrannosaur? Well if you scale something up so it increases by a factor of two, the length … the weight will actually increase by a factor of eight. So they would be eight times heavier, but the strength of the bones and the muscles will only increase by a factor of four, which is if you scaled up a cricket so it weighed a tonne, it wouldn't be able to move at all. So it can only jump due to that effect. So that's why little insects they are very … they can drag things that are very heavy. They can jump up many times their body height whereas an elephant cannot.
Another thing with T-rex, a scary thing with T-rex, if you compare what they have, they are trying to figure out how strong the jaws were compared to for example, the carcharodontosaurs which were of the same size, … and T-rex jaws would have been at least twice as strong, if not three times as strong. So they had tremendous biting power. They could literally crush the bones and if you've gone through the animatronic dinosaur gallery, you've seen there is one of the labels that talks about the T-rex poo they found, a big – seven kilograms big – poo. They had big chunks of crushed dinosaur bones in it. So T-rex had a bone crushing bite, very, very powerful jaws … and some recent studies on T-rex and one of its most common prey, Triceratops indicate that after killing Triceratops, it literally ripped the head off in one go to get to the neck muscles, probably just pinned the body with its big foot and then just tore the head off. Pretty brutal animals these.
An interesting thing with T-rex, if you look at the growth curve which they have figured out by cutting a cross section of the leg bone, it seems that the T-rex had a growth spurt between five to 15 years. It grew very fast. Then it reached maturity around 20 years and after it had reached maturity on average, they only seemed to have lived for another maybe five years. So they had a very, very tough life. Many of their skulls, if not most of the skulls of T-rex, have bite marks from other tyrannosaurs and imagine if you're going to go get your lunch and you have to go and kill a Triceratops. It's sort of dangerous business. [Addresses screen] And here is Triceratops. You can see those huge horns. Triceratops and T-rex, they were some of the very last non-avian dinosaurs that lived around 66 to 68 million years ago in America.
Not only did we have really large dinosaurs, we had some pretty huge crocodiles and we do have one Deinosuchus crocodile upstairs, a model, animatronic model and this is the skull of Deinosuchus and that was a dinosaur-eating crocodile, closely related to alligators and it lived in North America. We haven't found any really large Cretaceous crocodiles in Australia, but that might be just a matter of time since they are finding lots of dinosaurs and other creatures from the age of the dinosaurs, particularly in Queensland in the Winton Formation.
As a palaeontologist it's fantastic giving talks - that's one of the most fun things to do - but sometimes you go out in the field and that's also very fun. People in general probably don't have a full understanding on how we go about finding dinosaur fossils. One of the first things we do, if there's an area we've never worked on before, we try to get hold of as much as has been published about it as possible. Typically you start at any publication by the [WA] Geological Survey because they go out and they survey the ground. So they will know if there are rocks of the Cretaceous period, whether they were laid down in a river for example or if they are marine.
[Addresses screen] Now this is a type of rock that's called ‘badlands’. As a palaeontologist you would call them good lands. Badlands imply there is not much growing on it. The erosion rate is very high, but obviously if you don't have vegetation covering the ground it's much easier to actually find fossils.
Now this is an ant hill. It turns out that there is a type of ant – certainly in North America, it might be present elsewhere as well – and if they built their nest for example out in a badland area where there might be thin beds, what we call bone beds, that there might be lots of little – for example at the base of an ancient river channel – you can get an accumulation of little fragments of bones, maybe little teeth of raptor dinosaurs. If that's anywhere near where the ants have decided to build their ants' nest, they might be the only big, suitable particles around. So they will go to that outcrop, they will drag that little fossil and use it to build their ants nest.
So what do you do if you're a palaeontologist? Well one thing you can crawl across the outcrop … I mean, you can walk across the outcrop to find these big bones, but that's usually not what we do. First we want to see if there is any potential of bones to be preserved at all. So we look for these little tiny bones.
So a colleague of mine and myself, we went to Wyoming, it would have been late in 1990s and we came across these ant hills in dinosaur country. So we brought out our calico bags and we gently removed a big chunk of these ant hills. Now how do you extract the fossils out of the ant hills? Well we took them back to our hotel because there is not much else to do in the evening … and then we still had the problem, "How do we get the fossils out of this ant hill material?" because the ants were still there. They were very aggressive. We got bitten quite a bit. So we brought out the heavy artillery. Poor ants. I still feel bad about it, but they did it for the science.
Now, the best way, the most gentle way of extracting small fossils out of a sandstone or an ant hill, is to what we call wet sieve it. We have sieves and then you sieve it in some body of water, and a bathtub will actually work. It will work for a while because we had vast quantities of this ant hill material. So eventually they literally and this is a true story – the whole bath tub became clogged. So what do you do? Go to find another motel with an even fancier bathtub, and again … it's a true story, but don't tell anyone. We left a trail of destruction throughout Wyoming and Montana, but we got out some fantastic material and here it is.
[Addresses screen] These are some of the small fossils – we call them micro fossils – and each one of these fossils were initially collected by an ant in Wyoming. Can you believe that? For example, we have – you see those serrated teeth? They are from a dinosaur called Sauronitholestes which is the North American equivalent of Velociraptor. So you have little ants walking about: "Oh, there's a raptor tooth. Let's take that one and drag it back to the nest." Here we have crocodile teeth. We got plenty of teeth from rays and sharks and I also found a few teeth of birds, because during the Cretaceous period many of the birds still had teeth, or what we call the avian dinosaurs. So birds progressively lost their teeth over a 70 million year period.
Another interesting thing about this assemblage apart from being all collected by ants is that it's a mix of animals that lived on land, like the raptor dinosaurs, and animals that lived in rivers like the sawfish … and there's the tooth of piked dogfish shark. They don't really go up in rivers. They live in the sea. So why do you get this mix of these different animals? Well this was a floodplain environment quite close to the shore and if you imagine over hundreds of thousands of years, the sea level will fluctuate maybe up to ten to twenty metres. So when the sea level rises, the sea level what we call ‘transgresses’ and it will rework the floodplain sediment … and that's how you often get a mixing of animals, of remains from animals that lived on land and in the ocean.
But these are all now in the collections of the WA Museum, … and again, I thank the ants. So … most of the raptor dinosaur teeth that I have were collected by ants initially.
One thing people are also interested in when I give talks is "Well all right, it's fantastic to hear about all these stories about North American dinosaurs and African dinosaurs, but what about Australia? Where can I find dinosaurs in Australia?" Non-avian dinosaurs. Avian dinosaurs – you just go outside and they're everywhere, ten thousand species of avian dinosaurs.
In Western Australia the by far best locality for dinosaurs is up in the Broome sandstone where we have more than one hundred kilometres of track ways along the coast. But when it comes to bones, Western Australia is probably one of the worst places on the planet. We have only four bones that are definitely dinosaur bones. Two of them are from Geraldton from the Jurassic. We got one single toe bone from Gingin, the Molecap Hill Quarry and we got another Theropod tail vertebrae from Kalbarri, that's it. But the really good sites in Australia are down here in Victoria where they found polar dinosaurs because this area was very close to the South Pole 120 million years ago, and above all Winton in Queensland. They're finding so many dinosaurs there. So they're digging them up as we speak. They have dinosaur digs going on almost all the time. They have so many dinosaurs they have built a dinosaur museum up there.
One of the reasons why it's quite difficult to find dinosaur bones in Western Australia is the lack of clear good outcrops. [Addresses screen] This is a photograph of a site in Canada called the Dinosaur Provincial Park. You can see the very extensive outcrops … whereas this is me looking for dinosaurs near Moora and usually the outcrops are very small. So that just makes it harder to find it. Also the weathering is quite intense because the rock in Western Australia had been sitting quite close to sea level for tens of millions of years, so the weathering tended to destroy the bones over time.
I mentioned that Victoria was close to the South Pole … [addresses screen] and this is an artist's interpretation of some of these small Ornithopods. You have a couple of them in the animatronic dinosaur exhibit. We believe that they had some form of insulation because it would have been cold, especially in the winter. Small Ornithopods have been found in China showing that they had some hairlike filaments, not quite like feathers. We haven't found any dinosaurs within the Ornithischian group – they're all plant eaters – that had feathers, but we think that some of them probably had some sort of insulation.
Australovenator is by far the best preserved of the meat-eating dinosaurs from Australia from the Cretaceous period. It's probably the dominant meat-eating dinosaur and you can see here the main features are the huge claws on the hands. So they would probably be the main killing tools whereas Tyrannosaurus for example had very tiny little arms, two fingers, but a huge, massive head so it would have used its jaws to kill its prey, but Australovenator, probably not. Australovenator belonged to a group called the megaraptors. It's based on a dinosaur called Megaraptor that's found in South America. The first thing they found was these big claws … and initially they actually thought that it was a raptor dinosaur and that those claws actually belonged to the toes, but then when they found more complete remains they realised that that was not the case.
The Australovenator and the big sauropods they are finding in Winton, lots of sauropods, … they are most likely of the same type, titanosaurs as those making the sauropod track-ways up in Broome. There's one way of knowing that you had dinosaurs if you had track-ways. This is from the large quarry in Queensland. You can see numerous footprints here of small dinosaurs. Most of the footprints that we find up in Broome, they are really large, big, whopping sauropod prints, but that's in part due to the environment where you find [them]. They are right in the inter-tidal zone so it is more difficult for small ones or to spot small ones. They are more easily destroyed by the surf. Here's a typical big sauropod footprint. This is not from the Broome sandstone but from France I believe.
This could have been a scene along the shore up at Broome. We do know that we have raptor dinosaurs because they are finding teeth of raptor dinosaurs near Winton … [addresses screen] and here you can see a big titanosaur or similar sauropod defending its little one against one of these raptor dinosaurs. You can see the feathers there. What do they use the feathers for? Their wings were not big enough for them to fly or they were too heavy. One theory is that they used that huge claw to jump up onto their prey like small horned dinosaurs and dig in with their claws just like an eagle and just use their wings to keep the balance – eagles do that – and then just hold on 'til their prey collapses by shock or blood loss. So it would be quite slow and gruesome. The claws, they don't really have a sharp cutting edge, so they couldn’t really use them to slice up the side of the prey dinosaur.[Addresses screen] Here again it's me looking for dinosaurs. This is the right type of sediment. It's floodplain sediment of the right age, Cretaceous, but you can see the sediments are quite pale and that indicates that they are very deeply weathered. So we didn't find anything on that occasion.
This is an interesting bone that was lying misidentified in our collections. It was found in the 1960s at Gingin and it was misidentified as a marine crocodile, but a colleague came over from Melbourne and he wanted to go through our collection and he pulled out this bone and he had a look at it and it didn't quite look like a crocodile bone. So he handed it over to me and I said "No, not quite," and we both felt that it sort of resembled pterosaur bone because it was very light and spongy and pterosaurs had very spongy jaw bone whereas the jaw bone of a crocodile is very, very dense because they have very powerful jaws. You can see here these are empty tooth sockets. So we took it over to Queensland and compared with better preserved material of pterosaurs and this is the snout - part of the snout of a pterosaur found in Queensland, and sure enough it turns out to be one of these toothed pterosaurs with probably a wingspan of four to five metres.
So we had these flying across here, the Perth plain 100 million years ago. It's quite amazing. Pterosaurs, they did not survive the extinction that took place 66 million years ago. They are quite fascinating animals. I would have loved to see one of those flying … and some of them were absolutely enormous. As you go from the early Cretaceous into the late Cretaceous, they were absolutely enormous. [Addresses screen] These would have been … some of them were as tall as a giraffe and they were walking on their knuckles and they would have had a wingspan of maybe 10 to 12 metres, … and here they are portrayed as patrolling, looking for little baby sauropods like some modern birds do. Or they don't look for sauropods, but they pick up lizards and other things.
These are some of the outcrops where I do field work north of Kalbarri. You can see here we have a sandstone in the bottom. It was laid down in shallow water 120 million years ago and then we go up into deeper offshore sediments where you find a lot of fish remains, and the horizon right here we find bones of marine reptiles. We find bones of marine reptiles every time we go up there, … [addresses screen] and here's a volunteer. We often bring volunteers with us, … and he's found this bone of a reptile called an ichthyosaur … and here are some even better preserved. These were actually found near Gascoyne Junction by an amateur.
Amateurs are very important. They go out and they find fossils and sometimes there is very beneficial – mutually beneficial – cooperation between amateurs and professional palaeontologists. They are making the finds, they donate them and in return they might get a species named after them. They get to come along on field trips, … etc. This is just an image to show you how these ichthyosaurs looked like. So 120 million years ago these would have been swimming along the coast here in Western Australia.
We also found on one occasion a tail vertebrae of a huge animal called a pliosaur. These could grow to ten or eleven metres and would have been the apex predators. One palaeontologist estimated the jaw strength of Kronosaurus. According to him Kronosaurus had a skull up to three metres in length. According to him they had enough power in their jaws to flatten a small car. I think he specifically mentioned a Volkswagen, a small car. Very powerful jaws.
Sometimes when you go out looking for fossils – vertebrate fossils from backbone animals – you know pretty much you're not going to find anything enormous, but you might be interested in looking at what the fossils can tell you about the environments. [Addresses screen] Here we are north of Kalbarri. You can see we have sampled here bed by bed. I did the digging and they were just sitting there. They were splitting the rock open trying to find fish skeletons. So we wanted to see – this probably represents maybe 500,000 years – we wanted to see if there was change in the fish fauna going up in time that could indicate maybe that the temperature, maybe it got warmer or colder, or a change in sea level. So it's part of the interesting detective work you do as a palaeontologist, trying to go out and find evidence suggesting something about the environment, apart from finding new species.
And here I have taken samples because I wanted to look at fossil shark material. Sharks … they produce a lot of teeth, so mostly you work on teeth if you work on sharks. You can see here I've sampled, taking a big chunk out of this horizon here and filled my calico bags and after sieving it back in the lab, … look at these beautifully preserved fish bones and fish teeth. Now these are 93 million years old, but they look just modern apart from the colour, exceptionally well preserved. Western Australia has some of the best fossil fish sites from the Cretaceous period found anywhere in the world, … anywhere. Some of these layers north of Kalbarri I might find up to 1,000 fossil sharks’ teeth per kilogram of sediment, and here is just to show you how these fish would have looked like, Enchodontids. So they are quite common, or very common.
At other areas for example in the Giralia Range you can walk what is effectively ancient sea floors. Imagine you're out walking there and you know you're walking on 100 million years old sea floor and sure enough you have beautiful sharks’ teeth. This one is 100 million years. It's just recently weathering out of the rock. So there's some absolutely amazing fossil sites in Western Australia … and occasionally if you're really lucky you might come across a whole dentition of a shark which I did in 1996 and it turns out to be a whole new family of sharks, the biggest sharks of the Cretaceous period. This one was found on Cardabia Station, so we named it Cardabiodon. This is just to compare with a jaw of a modern mako shark, two and a half metres long. So they were quite a bit bigger.
This is just some of the creatures that we do find and that we are looking for, … and obviously this is from a vertebrate palaeontologist perspective. I've spoken exclusively of vertebrate fossils but there are all sorts of invertebrate fossils, clams, brachiopods, trilobites, a whole range of fossils that we have in our state. We have some beautiful localities yielding fossil plants down in the South West not too far from Perth, of Eocene age for example. So, Western Australia has some really world class fossil sites.
I think that was the last image, so I hope you enjoyed the talks and learned something about fossils and the methods we used – we and the ants – use to collect these fossils. So thank you.
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