Post by Grey on Jun 28, 2013 7:21:38 GMT 5
Dinosaurs of the 21st Century: masters of the sky
They ruled the land for 170 million years and now they rule the skies! Explore the wonders of the dinosaur world, from the mighty T-rex to the humble duck.
Chevron is a presenting partner of In the Wild West lecture series.
LINK: museum.wa.gov.au/explore/videos/dinosaurs-21st-century-masters-sky
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Transcript:
"Welcome to my talk this afternoon about ‘Dinosaurs of the 21st Century – masters of the skies’. When you talk about dinosaurs, we have to understand that they must have lived a very long time ago. The first dinosaurs, they evolved in the Triassic period about 230 million years ago. The Triassic, the Jurassic and the Cretaceous period, they are sometimes called the ‘Age of the Dinosaurs’ and they range from about 250 – they start at the Triassic to the end of the Cretaceous period about 65 million years ago.
If we go back a bit further in time to the Permian period, weÂ’ll notice that there were no dinosaurs around, but the dominant, land-living animals were called the synapsids. Now, synapsids is a group that also include mammals, but some of these early synapsids, they are called the therapsids, and this is one of the more famous ones, Dimetrodon found in rocks in North America. You can see it had this huge sail on the back. We think they used them to regulate their body heat, may be facing the sun, in the morning to heat up more quickly.
But as we go into the Triassic period, we notice that the therapsids, they become smaller in size, because they are now facing competition from a new group of vertebrate animals, the dinosaurs. Eventually most of these synapsids, they become really, really small, about that size, in the Triassic period about 230 million years ago, and they evolve into the first mammals. So this is one of our ancestors, whereas dinosaurs are not.
Now the first dinosaurs that we have any evidence of are about 230 million years old. This is Herrerasaurus, one of the best known of these really early dinosaurs from the Triassic period. ItÂ’s been found in rocks in Argentina, and you can see itÂ’s a meat-eating dinosaur, sharp teeth, strong jaws and it was a two-legged creature.
Now, when we discuss dinosaurs, we have to remember that there are two major groups of dinosaurs, and the way we classify them is by looking at the hip structure. These are the hip bones of one of the groups of dinosaurs, and these are the ones of the other type. Now you can see that there is a hole in the middle here where these three bones join. Now that is a character that is unique to dinosaurs.
This group is referred to as the saurischian dinosaurs. They include the meat eating dinosaurs like Tyrannosaurus rex. It also includes the giant Brontosaurus type, the big sauropod dinosaurs which were plant eating dinosaurs, whereas the ornithischians, they include various plant eating dinosaurs like Stegosaurus here for example.
If we start looking a bit more into detail at the saurischian dinosaurs, as we get into the Jurassic period, there is a general increase in size, if we look at the top predator, the dinosaurian top predator. This is a well known dinosaur from the upper Jurassic, about 150 million years old from North America called Allosaurus. It was really a large predator. It could grow up to possibly as much as 12 metres in length, and was certainly the apex predator on land in North America at that time. You can see it had really, really big claws, big strong arms and a large head. It would have been an absolutely formidable predator.
As we go into the Cretaceous period which is the last of the three eras that make up the Mesozoic, the Age of the Dinosaurs, some of these allosauroids that are related to Allosaurus, they are of gigantic size, and this is the biggest of these allosauroids. ItÂ’s Giganotosaurus. It has been found in rocks in Argentina about 100 million years old, and it was an absolute monster. It could grow to as much as maybe 14 metres in length.
This is the skull of Giganotosaurus and as you can see here – I’ll go back one step - the skull could reach almost two metres in length. Now that’s a big head. You can see that also it has quite a few openings in the skull and that is partly to make it lighter, but also to provide space for the jaw muscles, closing the jaw. So it had a powerful bite. The teeth are quite narrow, shaped a bit like a knife. So it could cut through the flesh of its prey.
This is just to give you an idea about how big Giganotosaurus was compared to a human. It would easily be able to swallow a human whole.
Along with these giant allosauroids – we call them theropods, the meat eating dinosaurs – so I’ve gone and used that term theropod – they were predominantly successful in the southern continents, or the Southern Hemisphere. In the Northern Hemisphere there was a group of rather small theropod dinosaurs, meat eating dinosaurs, called the coelurosaurians. We have evidence of them for example in North America, well preserved specimens, and they were about may be two metres in length. But as you go into the Cretaceous period, one branch of that group started increasing in size and eventually produced the gigantic tyrannosaurids. Now this is Tyrannosaurus itself, the biggest of these coelurosaurians. Although T-rex looks much like Giganotosaurus at a first glance, they’re actually not that closely related. T?rex had an absolutely massive skull. It had by far the strongest bite of any meat eating dinosaurs, and unlike Giganotosaurus, it had the ability to actually crush bone. It had a bone crushing dentition. The teeth are not particularly narrow. They are quite thick, shaped a bit like a banana. So it had an absolutely massive bite, very, very large head. We can see the arms are tiny and they only have two fingers. They’re arms, they’re so small. So we are not quite sure what they actually used these arms for. They weren’t even long enough to scratch themselves under the chin. So we are not sure. If you follow the evolution of this group, there is a general reduction of the size of the arms, but an increase in the size of the head. So they clearly wouldn’t have used them during their hunting, for example.
Now, this particular T-rex is one of the best known. ItÂ’s the largest, most complete T?rex skeleton ever found and people who work on these tyrannosaurids, they noticed there are two different morphs of T-rex. One is a bit larger and has robust bones. The other one is slightly smaller, still gigantic, but slightly smaller, a little bit more gracile. And some suspect that the larger morph represents the females, for examples in birds of prey the female is quite a bit bigger than the male, whereas in crocodiles for example, the male is much bigger than the females. They suspect that this larger form represents the females. So therefore, they called this one Sue. She is named after the lady who first found her bones.
ThereÂ’s an interesting story pertaining to this particular specimen. It was dug up by a company who specialises in collecting these dinosaur remains, but eventually it got confiscated by the FBI and people were put in jail and all sorts of drama. Eventually, the Chicago Field Museum ended up purchasing it for about $8 million. It takes a lot of time excavating these dinosaurs. So theyÂ’re not cheap if you want to buy one.
Another interesting development in the theropod dinosaurs, if you go from the Jurassic into the Cretaceous, especially in the tyrannosaurids, is the development of a stereoscopic vision. Now that’s a huge advantage if you are a hunter because it enables you to judge the distance. It’s also good – you don’t necessarily have to be hunting, but if you’re a climbing animal that’s also very necessary so you can judge the distance from one branch to another. Whereas if you are a herbivore like a wildebeest in Africa, it’s better to have the eyes on the side because you can scan the perimeter for predators.
ThereÂ’s been a bit of a dispute where the T-rex was an active predator. Almost all palaeontologists working on these theropod dinosaurs regard it as a predator, but there is one in particular who claimed that T-rex probably was a scavenger, because some parts of the brain that are related to the smell are well developed in T-rex. ItÂ’s a bit difficult to argue why T-rex needed to develop stereoscopic vision. It was just a scavenger. T-rex was, by far, the biggest of the theropods of its time, so it would be able to chase off any other predators from a kill.
Now, when we look on these theropods. It’s interesting to see the huge variety in shapes and the way the skeleton is made up. This is a most interesting theropod dinosaur found in the 1950s in Mongolia. Therizinosaurus – I can hardly pronounce that word – these claws are up to one metre in length. They are about that big and they are by far, the biggest claws of any animal. And when they first discovered this animal they, only found the arms and the shoulder blade. So they tried to figure out what the rest of the dinosaur looked like. May be it looked like a gigantic Tyrannosaurus rex for example. But when they found other related dinosaurs that belong to the same group as these ones, again with a big claw, a huge hand, it turns out it represented the most bizarre looking dinosaur you could possibly imagine and that just shows you how much there is to learn about these dinosaurs. Who could possibly have predicted that the owner of these arms would look something as silly, dare I say, as this one? This is a theropod that had abandoned the meat eating habit and turned into a herbivore. So it had a small head and it ate plants, had a big, huge gut and then these big whopping claws. Quite amazing.
Another very interesting group of theropod dinosaurs, they show what we call ‘convergence’ with the crocodiles. They are the spinosaurids. I’m not sure if any of you saw one of the Jurassic Park movies. There was one spinosaurid, Spinosaurus itself that was featured in that movie. I think it chomped or killed a T-rex. Possibly. Somewhat unlikely. Anyway, these spinosaurids, they were a fish eater. We can tell, if you look at the jaws here, they are narrow, just like in a fresh water crocodile. Now fresh water crocodiles, they are specialised in eating fish and the advantage of having narrow jaws if you are a crocodile and you feed exclusively on fish, is of course that you can close your jaws much quicker. If they are broad like in a salt water crocodile, you have to fight the resistance of the water as you close your jaws. But it’s a trade-off because the fresh water crocodile is not that terribly well adapted to grabbing hold of a pig for example. Then it’s better to have thick and heavy jaws.
These spinosaurids were clearly fish eaters. Some of the spinosaurids, like Baryonyx was found fish scales preserved in its abdominal cavity.
This is Spinosaurus itself. Spinosaurus had a huge sail like structure on its back and may be they used that for display, or may be that they used it to heat up quicker in the morning by facing the sun. We donÂ’t know, but they are most bizarre looking theropod dinosaurs. They had big - quite long arms, big claws. They would have been useful if you tried to catch a fish, a bit like a grizzly bear you can imagine. Spinosaurus was actually the largest of all theropods. Some remains indicated that they could grow may be to 16 or 17 metres. So they were absolutely enormous.
Now the other big group within the saurischian dinosaurs are the sauropods and this one, Apatosaurus, was also formerly known as Brontosaurus. The way it works when we name things, is that the oldest name thatÂ’s been properly published in the scientific journal has priority, and here, it turns out that Apatosaurus was the earliest name applied to this creature. But then it got forgotten and someone named it Brontosaurus. So thatÂ’s why we these days call it Apatosaurus rather than Brontosaurus.
The interesting thing about the sauropods apart from being the biggest – by far the biggest land living animals of any type, is that if you look at the vertebrae here, you can see that they are very, very light. They are what we called pneumatized. They would be air sacs penetrating into the bone making it much, much lighter. That’s an interesting character, because that’s seen also in birds.
The other big group apart from saurischian, are the ornithischians, and IÂ’m just going to show you some example of ornithischian dinosaurs. This belongs to a group called the marginocephalians and these are the ceratopsians. Some of my favourite dinosaurs with these huge structure behind the neck. Many of them had spines. We had Triceratops for example, big horns, and itÂ’s easy to imagine that this was used as a defence against the tyrannosaurids, because these were coeval will the tyrannosaurids in North America, but also in Asia. The ceratopsians, they evolved in Asia and then later migrated to North America, and it was for a long time believed that that migration took place across the Bering Straits. That was a land bridge that were present at times during the age of the dinosaurs. But just a few years ago I was part of a team that described the first ceratopsians from Europe and since that publication, there has been several examples of ceratopsians described from Europe. So itÂ’s possible that they may be managed to get to North America via Europe as well, Northern Europe.
HereÂ’s another group of marginocephalians. TheyÂ’re the pachycephalosaurs, a most bizarre looking dinosaur. Now this bony dome could be up to 10 centimetres thick, the actual bone itself. It looks like something from a science fiction movie, doesnÂ’t it? And obviously palaeontologists, they have speculated what they used this for. May be they were head butting each other. May be the male used it to head butt each other, but itÂ’s hard to tell. But interestingly, most of them are quite small. They werenÂ’t very big dinosaurs, so possibly they could use it as a defence as well.
The other group, the shield bearers, the thyreophorans. Again, these were slow moving animals. They wouldnÂ’t be able to outrun a big theropod for example. So they instead had a more passive defence in the shape of bony scutes in the skin. Many of them had sharp cusps and had big spikes. Some of them had an active weapon at the end of the tail, a huge bony club and by swinging that back and forth they would be able to cripple a T-rex that would come too close. So they would be quite formidable animals to subdue.
We have the Stegosaurus, another group, and there’s little doubt what they used the spikes at the end of the tail for. They obviously were used for defence. Now these plates on the back on the other hand, they are a little bit more difficult to explain. It seems that they had a lot of blood vessels. So may be they used them to heat up in the morning – that’s possible – by facing the sun. We are not quite sure what they used them for.
The other big group of ornithischians represents the ornithopods, the Hadrosaurus. Again, they were featured in the Jurassic Park movie. We have an ornithopod found in Australia, a large one, Muttaburrasaurus. If youÂ’ve ever been to the Diamonds to Dinosaurs gallery in Perth youÂ’ll see that we have a cast of one of these ornithopods, Muttaburrasaurus, about 7.5 metres in length.
Thomas Huxley, a British biologist and most of the time a strong support of Charles Darwin who presented his Theory of Evolution that life on Earth has progressed through evolution to create more advanced forms. Now he presented an idea in 1880 that birds evolved from dinosaurs and that was met with significant scepticism. Now, Huxley, he looked at the oldest known bird that has ever been found in rocks of 150 million years old in Germany, Archaeopteryx. Now Archaeopteryx displays features, that some are very birdlike, like they have wings, feathers like a bird, whereas it has a long tail like a dinosaur and it also had teeth like a dinosaur. But most features indicate that it was a bird and is generally classified as a bird. This is a reconstruction of Archaeopteryx, 150 million years old creature.
But Huxley, he pointed out that some of the small theropods of the same age in the same general area in north west Europe, looked very much like Archaeopteryx if he just removed the feathers. This is Compsognathus, one of these small theropods. That was the basis for his idea that birds actually had evolved from dinosaurs. This is a reconstruction of the skeleton of this small compsognathid dinosaur.
However, as we go into the early 1900s, 1920 to 1969, I call it The Dark Ages in dinosaur research. Palaeontologists, they had abandoned the idea that there was a close link between birds and dinosaurs and they started regarding them again as cold blooded, slow, dumb creatures. This is a classic illustration showing a T-rex walking up towards a group of Triceratops and it is walking upright, standing almost like a kangaroo when they are resting, with the tail dragging behind its legs. We found lots of track ways from sauropods and from theropods and none of them show any tail dragging, for example.
But in 1969 there was an amazing find? published in North America. John Ostrom describes the ‘terrible claw’ Deinonychus. Now this was a most fearsome looking dinosaur. It could grow to about 3-3.5 metres, but on the second toe it had a huge enlarged claw, raptorial claw and they probably held that off the ground when they were walking. Steven Spielberg picked up on this in his Jurassic Park movies and he used one of these raptor, Velociraptor which is actually a smaller raptor, smaller than Deinonychus, but he used the name – he probably liked the name Velociraptor. But the size of the raptor’s featured in those movies is more representative of – corresponds better to Deinonychus.
This is the skeleton of Deinonychus. Other interesting features – they had ossified tendons like bony rods, so they could hold their tail well off the ground rather stiff as a counter balance to the anterior portion of the body. The arms were big, the hands are almost bigger than the feet, and that’s another characteristic of these raptor dinosaurs. They also had a well developed sternum, much like birds. Some had an external keel, and in birds that keel is the attachment site for their pectoral muscles, their big flight muscles in the flying birds.
Now in the Jurassic Park movies, the raptor dinosaurs, they were portrayed as really vicious, aggressive, intelligent creatures. Now this is one of the most amazing fossils - dinosaur fossils that has ever been found. It was found in rocks about 80 million years old in Mongolia and it shows Velociraptor itself holding onto the head of a ceratopsian dinosaur, and they probably died as a result of a collapsing, may be wet sand dune that collapsed on top of them. You can see here that it looks like the ceratopsian is actually holding onto one of its arms in its jaws. Now, this, the Protoceratops, the ceratopsian in question, would have been a rather slow animal. So thereÂ’s no way it would be able to outrun the raptors. It shows that the raptors had no difficulties or wouldnÂ’t hesitate taking a plant-eating dinosaur who was much bigger than itself.
Now the idea that Ostrom again, he revitalised the idea between a close link between small theropod dinosaurs and birds, in particular the raptor dinosaurs and birds. And that idea grew in popularity amongst palaeontologists working with dinosaurs, and even more so when we started finding a whole range of small raptor dinosaurs in 120 million year old lake deposits in China. Now this is one of the most common raptor dinosaurs found in these Chinese lake deposits – Microraptor. This is the skeleton and not only do we find the skeleton of dinosaurs in these lake deposits, we also find a lot more. Now again, this is Microraptor. That’s the head, this is the arm, that’s a leg, the tail and these are flight feathers. It turns out that almost all the raptors we are finding in these Chinese lake deposits, certainly those that are really well preserved, they were covered in feathers. They had flight feathers as well. You can see it has flight feathers on its leg. It even has feathers at the end of the tail. Most likely it climbed trees and then it could glide maybe from one tree to another, but it appears it also was probably able of some sustained flight, and that was used – like some of the arguments in the 1920s, 1930s and a bit later, why birds couldn’t have been derived from dinosaurs because dinosaurs, they don’t have feathers. Well, now we know that they do. They were covered in feathers.
Not only are we finding feathers in raptor dinosaurs, but also in some of the more, what we call, basal or theropod dinosaurs that are more distantly related to the raptor dinosaurs. But again, some palaeontologists working on birds and some ornithologists, they said “Oh well, yeah, we agree. Some of the raptor dinosaurs, they had feathers, but there are certain skeletal structures in birds that are not present in dinosaurs.” One is the wishbone. The collarbones are fused in birds to form the wishbone. So they said “Well look, we don’t have any wishbones in any dinosaurs.” It didn’t take long for us to start finding wishbones in dinosaurs. Raptor dinosaurs, they had wishbones. So there goes that objection.
But then they pointed out again that, well, “Birds they have a most unique set of lungs.” The way a bird breathes is not like us. We inhale the air in the lungs and then we expel it, like a bellow, in out, in out. The way it works in a bird is quite different. They have an extremely efficient way of getting rid of CO2 and extracting oxygen. Now apart from the lungs – and the lungs in a bird, they’re not squishy like ours. They are quite stiff. Our lungs have little tiny alveoli, dead-end alveoli. You don’t have that in birds at all, and in addition to the lungs, they have several pairs of air sacs. One of them is unpaired, the clavicular air sac. But they have anterior thoracic air-sacs, posterior thoracic air sacs and abdominal air sacs. I’ll show you how it all works.
The way it works when a bird breathes; it inhales air here, but instead of going into the lungs, it goes into the posterior air sacs. So the posterior air sacs expand. They are sucking in air here, but then you have an anterior set of air sacs that also expands at the same time when the bird inhales. So air is going in here, but on the other hand – and then you have the valve-like structure here, where at least it works like a valve because when you dissect a bird you don’t really find a typical valve. So when this anterior air sac, when that expands, it sucks the air out of the lungs. And then when the bird exhales, there is a valve like mechanism here that prevents this air that’s now in the posterior air sac from going out the other way. So when they contract, the anterior air sac and the posterior air sac, that air is now going out here, whereas this air is now going into the lung. So that means that the whole system works like a one-way. Air comes in here and then it goes out there. So there is never any real mixing of air that is enriched now in CO2, carbon dioxide, with oxygen rich air.
For our lungs to work as efficient, if we would have to be able to exhale all the air, and we can’t – we can’t really collapse our lungs – so it is a superior way of extracting oxygen. The interesting thing also about this system is that these air sacs. They have little projections that actually grow into some of the bones, into the vertebrae for example and make them lighter. The clavicular air sac have projection that grows into the wishbone, and the ornithologists, they pointed out “Well, if dinosaurs were birds, shouldn’t they have the same advanced breathing system? Shouldn’t we see evidence in the skeleton indicating these, what we call pneumatization, these holes where part of the air sac had grown into the bone?”
Well, a couple of years ago palaeontologist Paul Sereno and colleagues described the first case of a pneumatized wishbone in a theropod dinosaur. So there we go again. What we thought was absolutely unique character to birds is now present in at least one theropod. ItÂ’s probably present in other theropods as well, but in order to find this structure preserved, the bone has to be exceptionally well preserved. In most cases when we find dinosaur bones, they have lots of minerals encrusting the bones and we might not see all the small foramina. So it partly was a result of an exceptional state of preservation.
So here we have what we thought were absolutely unique characters to birds present in dinosaurs as well. This is by the way the wishbone of one of the goose species, the Magpie Goose.
This particular theropod, Aerosteon, had lots of well pneumatised vertebrae. You can see here the space here where the extensions probably from the cervical air sacs. So actually not really that involved in the actual respiration, and saurischian dinosaurs, they tend to have them all along the vertebral column. But then more importantly is the presence of these holes, these foramina in bones where there really could only be supplied with the extension of the air sacs, from air sacs that are directly involved in the respiration.
So it appears that dinosaurs, they were not these slow, cold-blooded creatures that they were portrayed in the mid 1900s, around 1950 thereabouts. Instead they were highly efficient. The mere fact that many of them were covered in feathers, not only raptors, but other theropods as well, thatÂ’s a good sign of the creature being warm-blooded because that provides an insulation if youÂ’re rather small. Whereas if youÂ’re very big you donÂ’t need really any feathers or much hair for that matter. I mean look at elephants for example.
Now, as a result we now have changed the view on how we view birds from a classification point of view. There are so many characters that link birds to raptor dinosaurs. So it becomes almost ridiculous trying to argue that birds are not closely related to dinosaurs. In fact they are so closely related to dinosaurs, so we now classify them as dinosaurs.
This is just to give you a general idea about how we classify them. Here we have the main division into the ornithischians, the plant-eating dinosaurs, and the saurischians, the meat-eating dinosaurs which also include the plant-eating sauropods. You can see here up at the top we have the penguin, a bird grouped together with the raptor dinosaurs. So it appears that the birds are deeply nested within the dinosaur tree. So that also means that the dinosaurs actually didnÂ’t go extinct at the end of the Cretaceous, 65 million years ago. They survived. We have 10,000 species of dinosaurs living. IsnÂ’t that encouraging?
When we talk about dinosaurs we have to remember that you often find different dinosaurs in the Northern Hemisphere compared to the Southern Hemisphere. The configuration of continents was different back 150 million years ago for example, than it is today. In the Southern Hemisphere all the continents were joined together into a supercontinent called Gondwana. So we find similar dinosaurs in South America and Australia. They could migrate from one continent to another. Maybe that was a dinosaur?
In Australia, we donÂ’t have too many places where you can find dinosaurs. We have two main sites. One is in Victoria, some coastal cliffs where they are excavating lots of dinosaurs, but mostly itÂ’s isolated bones. They havenÂ’t found any complete skeletons of dinosaurs there, but lots of smaller ones, particularly smaller ornithopod dinosaurs in particular.
The other area is in Queensland. There are a couple of sites up there. We have Minmi, the most complete dinosaur ever found in Australia. It belonged to this group, the thyreophorans, the Shield Bearers. Another one Muttaburrasaurus, and as I mentioned, we have a cast of a Muttaburrasaurus skeleton on display in the Diamonds to Dinosaurs gallery. IÂ’m sure you all have visited.
But the main site finding dinosaurs in Australia is a town in central Queensland called Winton. They are excavating dinosaurs in Winton as we speak. Just a couple of years ago they described Australovenator. That’s the most complete meat-eating dinosaur ever found in Australia. It had big – there we are – big claws on the hand, and it would have been may be about five metres in length. And apart from Australovenator they also described two species of large sauropod dinosaurs belonging to a group called the titanosaurs. Diamantinasaurus is one of them. It was a very robust, stocky sauropod, may be 17-18 metres in length and would have been quite heavy, possibly weighing as much 15 or may be 20 tonnes.
The other one, Wintonotitan, obviously named after Winton, is small. ItÂ’s about the same length, but a little bit more gracile, may be not quite as heavy, but still gigantic. Now theyÂ’re finding so many dinosaurs in Winton, so they build a dinosaur museum there. So if you ever go to Winton, check out their museum. I think itÂ’s called Age of the Dinosaurs.
Now what about Western Australia? Well this is actually a photograph of me out at the site near Moora looking for dinosaurs, and I almost look a little bit depressed there as if I haven’t found anything. Now, over the last 100 years we’ve been looking and looking for dinosaur bones in Western Australia and we’ve found five fragmentary bones. That’s it. Five bones. I didn’t find any bones on that day, or the next day for that matter, but I certainly kept trying. When you look for dinosaur bones you don’t want to look in marine sediments that were laid down in the ocean, because you wouldn’t find any dinosaurs there. You want to look – the best type of sediment is what we call floodplain sediments - sediments that were laid down on floodplain, typically during a flooding episode. Maybe dinosaurs drowned trying to cross a river and their carcasses were swept away and ended up may be a point bar in the river and they were covered by sediments. So you want to look at a floodplain sediment obviously from the age of the dinosaur. This is the right type of sediment of the right age, but we didn’t find any.
Here I am again looking into the hillside. This particular outcrop here, thereÂ’s an alternation between sand and fine mud, and that is probably whatÂ’s referred to as a crevasse splay deposit. During a flood episode when you have the strongest flow, you get a lot of sand spread over the river banks and then followed by mud. You tend to get sand and then mud, and that might represent a single flooding episode. I didnÂ’t find any here.
The main reason why we donÂ’t find dinosaur in Australia, apart from the possible fact that I might be totally incompetent when it comes to finding dinosaurs, thatÂ’s possible, is that 140 million years ago Australia started separating from India or the part of India that is now under the Himalayas. So it was just drifting apart. When a continent splits up into two continents, the first thing you get is a rift valley. ThereÂ’s a place in east Africa called the East African Rift Valley, and if you go to Perth, you can actually see the remnants of that rift valley. ThatÂ’s the Darling Fault. ThatÂ’s part of that rift valley, when Western Australia drifted apart from India 140 million years ago.
But what happens now when two continental plates just drift apart is that you donÂ’t get much of what we call uplift. Whereas in the other scenario where two continental plates collide, one of them will be forced underneath the other, and you get the formation of the mountain range. The Andes is a good example where an oceanic plate is forced underneath a continental plate and you get the mountain formation. So that means the whole rock rises up and you get increased erosion and a constant supply of fresh rock. But if part of a continent sits near the sea level for tens of millions of years or hundreds of millions of years, it will be very deeply weathered. ThatÂ’s a problem.
IÂ’m sure there were dinosaur bones here originally but they most likely have been leached by rainwater for example. Rainwater is a bit acidic. Rain picks up CO2 and forms carbonic acid, and it will leach out bones over time. It was a very scenic place. ItÂ’s a real shame I didnÂ’t find any fossils.
On the other hand in April I went on a little trip to Alberta in Canada. This is a fantastic place. ItÂ’s may be 50 kilometres north of a town called Drumheller and this area is called the Dinosaur Provincial Park. IÂ’m sure you can figure out why itÂ’s called Dinosaur Provincial Park. ItÂ’s just full of dinosaur bones. These are the right type of sediments, about 75 million years old, floodplain settlements. You imagine meandering rivers working their way towards the ocean and during flooding episodes, thatÂ’s when you get sediments spread over the floodplain, and may be dinosaurs drowned and you can later find their bones sticking out of the rock.
Now I couldnÂ’t help myself, but I went down into these gullies and started looking for bones, and guess how long it took for me to find a bone? In Western Australia it takes on average 20 years. Anyone? No, it took me 20 minutes. It took me 20 minutes. There it is. ItÂ’s probably part of a leg bone. Yeah, 20 minutes to find a bone, and I was looking in an area where thereÂ’d been a lot of tourists. So itÂ’s been picked out pretty well. In some areas of the parks, there are so many dinosaur bones you have to be careful where you put the foot down, or youÂ’ll step on a dinosaur bone.
IÂ’ve been to similar outcrops in Montana in the US and in some places you can just sit down and start picking up teeth of raptor dinosaurs. One of the best places to look for small dinosaur bones and small dinosaur teeth, is thereÂ’s a particular species of ant that, whenever they build their little ant nest, if there are little fossils they will actually pick up the fossils. So the ant hill might be made up of one quarter of vertebrate fossils from the age of the dinosaurs. So if youÂ’re real mean and sieve the ant hill, the ants get a bit upset, you might find a lot of vertebrate fossils.
Now although we donÂ’t have many dinosaur bones from Western Australia, we have some really good dinosaur footprint sites, well one site, up in the Dampier Peninsula, all the way from a bit south of Broome and for a stretch of almost 100 kilometres, and particularly footprints of sauropod dinosaurs are very common and this image here, you can see a track way of a sauropod dinosaur walking along.
Sauropods, obviously they would have been very large animals, they were very heavy. You can see here where he puts his foot down, itÂ’s so heavy so the layers underneath here have actually buckled. You can see the deformation going down may be half a metre due to the sheer weight of these sauropods. Some sauropods may have weighed as much as 50 metric tonnes, like five or six/seven African bull elephants.
That was the last image I had and I thought this was rather suitable – Kentucky Fried dinosaur. The main message is basically that although it is a tragedy that all the large dinosaurs died out 65 million years ago, we should embrace the fact that we have about 10,000 species of living dinosaurs, and that palaeontologists working on dinosaurs these days, they will almost no exception classify birds without a doubt, as dinosaurs, because all the characters that had been used to differentiate birds from dinosaurs, we are now finding these characters in dinosaurs as well. When you look at many birds, there were quite a few ancient bird groups in the Cretaceous, those birds have now gone extinct, that again show many intermediate stages between a typical dinosaur and a bird dinosaur. For example, they might have a longer tail or may be they had a short tail of modern birds, but they had instead teeth, proper teeth for example. I’ve collected bird teeth myself in rocks 80 million years old in Wyoming, from an ant hill. Yeah, I’m sure they forgive me, the ants.
So basically, that was the last image I have and IÂ’m glad you all came to listen to this and hopefully youÂ’ve learned a bit about dinosaurs, and birds.
Thank you."
They ruled the land for 170 million years and now they rule the skies! Explore the wonders of the dinosaur world, from the mighty T-rex to the humble duck.
Chevron is a presenting partner of In the Wild West lecture series.
LINK: museum.wa.gov.au/explore/videos/dinosaurs-21st-century-masters-sky
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Transcript:
"Welcome to my talk this afternoon about ‘Dinosaurs of the 21st Century – masters of the skies’. When you talk about dinosaurs, we have to understand that they must have lived a very long time ago. The first dinosaurs, they evolved in the Triassic period about 230 million years ago. The Triassic, the Jurassic and the Cretaceous period, they are sometimes called the ‘Age of the Dinosaurs’ and they range from about 250 – they start at the Triassic to the end of the Cretaceous period about 65 million years ago.
If we go back a bit further in time to the Permian period, weÂ’ll notice that there were no dinosaurs around, but the dominant, land-living animals were called the synapsids. Now, synapsids is a group that also include mammals, but some of these early synapsids, they are called the therapsids, and this is one of the more famous ones, Dimetrodon found in rocks in North America. You can see it had this huge sail on the back. We think they used them to regulate their body heat, may be facing the sun, in the morning to heat up more quickly.
But as we go into the Triassic period, we notice that the therapsids, they become smaller in size, because they are now facing competition from a new group of vertebrate animals, the dinosaurs. Eventually most of these synapsids, they become really, really small, about that size, in the Triassic period about 230 million years ago, and they evolve into the first mammals. So this is one of our ancestors, whereas dinosaurs are not.
Now the first dinosaurs that we have any evidence of are about 230 million years old. This is Herrerasaurus, one of the best known of these really early dinosaurs from the Triassic period. ItÂ’s been found in rocks in Argentina, and you can see itÂ’s a meat-eating dinosaur, sharp teeth, strong jaws and it was a two-legged creature.
Now, when we discuss dinosaurs, we have to remember that there are two major groups of dinosaurs, and the way we classify them is by looking at the hip structure. These are the hip bones of one of the groups of dinosaurs, and these are the ones of the other type. Now you can see that there is a hole in the middle here where these three bones join. Now that is a character that is unique to dinosaurs.
This group is referred to as the saurischian dinosaurs. They include the meat eating dinosaurs like Tyrannosaurus rex. It also includes the giant Brontosaurus type, the big sauropod dinosaurs which were plant eating dinosaurs, whereas the ornithischians, they include various plant eating dinosaurs like Stegosaurus here for example.
If we start looking a bit more into detail at the saurischian dinosaurs, as we get into the Jurassic period, there is a general increase in size, if we look at the top predator, the dinosaurian top predator. This is a well known dinosaur from the upper Jurassic, about 150 million years old from North America called Allosaurus. It was really a large predator. It could grow up to possibly as much as 12 metres in length, and was certainly the apex predator on land in North America at that time. You can see it had really, really big claws, big strong arms and a large head. It would have been an absolutely formidable predator.
As we go into the Cretaceous period which is the last of the three eras that make up the Mesozoic, the Age of the Dinosaurs, some of these allosauroids that are related to Allosaurus, they are of gigantic size, and this is the biggest of these allosauroids. ItÂ’s Giganotosaurus. It has been found in rocks in Argentina about 100 million years old, and it was an absolute monster. It could grow to as much as maybe 14 metres in length.
This is the skull of Giganotosaurus and as you can see here – I’ll go back one step - the skull could reach almost two metres in length. Now that’s a big head. You can see that also it has quite a few openings in the skull and that is partly to make it lighter, but also to provide space for the jaw muscles, closing the jaw. So it had a powerful bite. The teeth are quite narrow, shaped a bit like a knife. So it could cut through the flesh of its prey.
This is just to give you an idea about how big Giganotosaurus was compared to a human. It would easily be able to swallow a human whole.
Along with these giant allosauroids – we call them theropods, the meat eating dinosaurs – so I’ve gone and used that term theropod – they were predominantly successful in the southern continents, or the Southern Hemisphere. In the Northern Hemisphere there was a group of rather small theropod dinosaurs, meat eating dinosaurs, called the coelurosaurians. We have evidence of them for example in North America, well preserved specimens, and they were about may be two metres in length. But as you go into the Cretaceous period, one branch of that group started increasing in size and eventually produced the gigantic tyrannosaurids. Now this is Tyrannosaurus itself, the biggest of these coelurosaurians. Although T-rex looks much like Giganotosaurus at a first glance, they’re actually not that closely related. T?rex had an absolutely massive skull. It had by far the strongest bite of any meat eating dinosaurs, and unlike Giganotosaurus, it had the ability to actually crush bone. It had a bone crushing dentition. The teeth are not particularly narrow. They are quite thick, shaped a bit like a banana. So it had an absolutely massive bite, very, very large head. We can see the arms are tiny and they only have two fingers. They’re arms, they’re so small. So we are not quite sure what they actually used these arms for. They weren’t even long enough to scratch themselves under the chin. So we are not sure. If you follow the evolution of this group, there is a general reduction of the size of the arms, but an increase in the size of the head. So they clearly wouldn’t have used them during their hunting, for example.
Now, this particular T-rex is one of the best known. ItÂ’s the largest, most complete T?rex skeleton ever found and people who work on these tyrannosaurids, they noticed there are two different morphs of T-rex. One is a bit larger and has robust bones. The other one is slightly smaller, still gigantic, but slightly smaller, a little bit more gracile. And some suspect that the larger morph represents the females, for examples in birds of prey the female is quite a bit bigger than the male, whereas in crocodiles for example, the male is much bigger than the females. They suspect that this larger form represents the females. So therefore, they called this one Sue. She is named after the lady who first found her bones.
ThereÂ’s an interesting story pertaining to this particular specimen. It was dug up by a company who specialises in collecting these dinosaur remains, but eventually it got confiscated by the FBI and people were put in jail and all sorts of drama. Eventually, the Chicago Field Museum ended up purchasing it for about $8 million. It takes a lot of time excavating these dinosaurs. So theyÂ’re not cheap if you want to buy one.
Another interesting development in the theropod dinosaurs, if you go from the Jurassic into the Cretaceous, especially in the tyrannosaurids, is the development of a stereoscopic vision. Now that’s a huge advantage if you are a hunter because it enables you to judge the distance. It’s also good – you don’t necessarily have to be hunting, but if you’re a climbing animal that’s also very necessary so you can judge the distance from one branch to another. Whereas if you are a herbivore like a wildebeest in Africa, it’s better to have the eyes on the side because you can scan the perimeter for predators.
ThereÂ’s been a bit of a dispute where the T-rex was an active predator. Almost all palaeontologists working on these theropod dinosaurs regard it as a predator, but there is one in particular who claimed that T-rex probably was a scavenger, because some parts of the brain that are related to the smell are well developed in T-rex. ItÂ’s a bit difficult to argue why T-rex needed to develop stereoscopic vision. It was just a scavenger. T-rex was, by far, the biggest of the theropods of its time, so it would be able to chase off any other predators from a kill.
Now, when we look on these theropods. It’s interesting to see the huge variety in shapes and the way the skeleton is made up. This is a most interesting theropod dinosaur found in the 1950s in Mongolia. Therizinosaurus – I can hardly pronounce that word – these claws are up to one metre in length. They are about that big and they are by far, the biggest claws of any animal. And when they first discovered this animal they, only found the arms and the shoulder blade. So they tried to figure out what the rest of the dinosaur looked like. May be it looked like a gigantic Tyrannosaurus rex for example. But when they found other related dinosaurs that belong to the same group as these ones, again with a big claw, a huge hand, it turns out it represented the most bizarre looking dinosaur you could possibly imagine and that just shows you how much there is to learn about these dinosaurs. Who could possibly have predicted that the owner of these arms would look something as silly, dare I say, as this one? This is a theropod that had abandoned the meat eating habit and turned into a herbivore. So it had a small head and it ate plants, had a big, huge gut and then these big whopping claws. Quite amazing.
Another very interesting group of theropod dinosaurs, they show what we call ‘convergence’ with the crocodiles. They are the spinosaurids. I’m not sure if any of you saw one of the Jurassic Park movies. There was one spinosaurid, Spinosaurus itself that was featured in that movie. I think it chomped or killed a T-rex. Possibly. Somewhat unlikely. Anyway, these spinosaurids, they were a fish eater. We can tell, if you look at the jaws here, they are narrow, just like in a fresh water crocodile. Now fresh water crocodiles, they are specialised in eating fish and the advantage of having narrow jaws if you are a crocodile and you feed exclusively on fish, is of course that you can close your jaws much quicker. If they are broad like in a salt water crocodile, you have to fight the resistance of the water as you close your jaws. But it’s a trade-off because the fresh water crocodile is not that terribly well adapted to grabbing hold of a pig for example. Then it’s better to have thick and heavy jaws.
These spinosaurids were clearly fish eaters. Some of the spinosaurids, like Baryonyx was found fish scales preserved in its abdominal cavity.
This is Spinosaurus itself. Spinosaurus had a huge sail like structure on its back and may be they used that for display, or may be that they used it to heat up quicker in the morning by facing the sun. We donÂ’t know, but they are most bizarre looking theropod dinosaurs. They had big - quite long arms, big claws. They would have been useful if you tried to catch a fish, a bit like a grizzly bear you can imagine. Spinosaurus was actually the largest of all theropods. Some remains indicated that they could grow may be to 16 or 17 metres. So they were absolutely enormous.
Now the other big group within the saurischian dinosaurs are the sauropods and this one, Apatosaurus, was also formerly known as Brontosaurus. The way it works when we name things, is that the oldest name thatÂ’s been properly published in the scientific journal has priority, and here, it turns out that Apatosaurus was the earliest name applied to this creature. But then it got forgotten and someone named it Brontosaurus. So thatÂ’s why we these days call it Apatosaurus rather than Brontosaurus.
The interesting thing about the sauropods apart from being the biggest – by far the biggest land living animals of any type, is that if you look at the vertebrae here, you can see that they are very, very light. They are what we called pneumatized. They would be air sacs penetrating into the bone making it much, much lighter. That’s an interesting character, because that’s seen also in birds.
The other big group apart from saurischian, are the ornithischians, and IÂ’m just going to show you some example of ornithischian dinosaurs. This belongs to a group called the marginocephalians and these are the ceratopsians. Some of my favourite dinosaurs with these huge structure behind the neck. Many of them had spines. We had Triceratops for example, big horns, and itÂ’s easy to imagine that this was used as a defence against the tyrannosaurids, because these were coeval will the tyrannosaurids in North America, but also in Asia. The ceratopsians, they evolved in Asia and then later migrated to North America, and it was for a long time believed that that migration took place across the Bering Straits. That was a land bridge that were present at times during the age of the dinosaurs. But just a few years ago I was part of a team that described the first ceratopsians from Europe and since that publication, there has been several examples of ceratopsians described from Europe. So itÂ’s possible that they may be managed to get to North America via Europe as well, Northern Europe.
HereÂ’s another group of marginocephalians. TheyÂ’re the pachycephalosaurs, a most bizarre looking dinosaur. Now this bony dome could be up to 10 centimetres thick, the actual bone itself. It looks like something from a science fiction movie, doesnÂ’t it? And obviously palaeontologists, they have speculated what they used this for. May be they were head butting each other. May be the male used it to head butt each other, but itÂ’s hard to tell. But interestingly, most of them are quite small. They werenÂ’t very big dinosaurs, so possibly they could use it as a defence as well.
The other group, the shield bearers, the thyreophorans. Again, these were slow moving animals. They wouldnÂ’t be able to outrun a big theropod for example. So they instead had a more passive defence in the shape of bony scutes in the skin. Many of them had sharp cusps and had big spikes. Some of them had an active weapon at the end of the tail, a huge bony club and by swinging that back and forth they would be able to cripple a T-rex that would come too close. So they would be quite formidable animals to subdue.
We have the Stegosaurus, another group, and there’s little doubt what they used the spikes at the end of the tail for. They obviously were used for defence. Now these plates on the back on the other hand, they are a little bit more difficult to explain. It seems that they had a lot of blood vessels. So may be they used them to heat up in the morning – that’s possible – by facing the sun. We are not quite sure what they used them for.
The other big group of ornithischians represents the ornithopods, the Hadrosaurus. Again, they were featured in the Jurassic Park movie. We have an ornithopod found in Australia, a large one, Muttaburrasaurus. If youÂ’ve ever been to the Diamonds to Dinosaurs gallery in Perth youÂ’ll see that we have a cast of one of these ornithopods, Muttaburrasaurus, about 7.5 metres in length.
Thomas Huxley, a British biologist and most of the time a strong support of Charles Darwin who presented his Theory of Evolution that life on Earth has progressed through evolution to create more advanced forms. Now he presented an idea in 1880 that birds evolved from dinosaurs and that was met with significant scepticism. Now, Huxley, he looked at the oldest known bird that has ever been found in rocks of 150 million years old in Germany, Archaeopteryx. Now Archaeopteryx displays features, that some are very birdlike, like they have wings, feathers like a bird, whereas it has a long tail like a dinosaur and it also had teeth like a dinosaur. But most features indicate that it was a bird and is generally classified as a bird. This is a reconstruction of Archaeopteryx, 150 million years old creature.
But Huxley, he pointed out that some of the small theropods of the same age in the same general area in north west Europe, looked very much like Archaeopteryx if he just removed the feathers. This is Compsognathus, one of these small theropods. That was the basis for his idea that birds actually had evolved from dinosaurs. This is a reconstruction of the skeleton of this small compsognathid dinosaur.
However, as we go into the early 1900s, 1920 to 1969, I call it The Dark Ages in dinosaur research. Palaeontologists, they had abandoned the idea that there was a close link between birds and dinosaurs and they started regarding them again as cold blooded, slow, dumb creatures. This is a classic illustration showing a T-rex walking up towards a group of Triceratops and it is walking upright, standing almost like a kangaroo when they are resting, with the tail dragging behind its legs. We found lots of track ways from sauropods and from theropods and none of them show any tail dragging, for example.
But in 1969 there was an amazing find? published in North America. John Ostrom describes the ‘terrible claw’ Deinonychus. Now this was a most fearsome looking dinosaur. It could grow to about 3-3.5 metres, but on the second toe it had a huge enlarged claw, raptorial claw and they probably held that off the ground when they were walking. Steven Spielberg picked up on this in his Jurassic Park movies and he used one of these raptor, Velociraptor which is actually a smaller raptor, smaller than Deinonychus, but he used the name – he probably liked the name Velociraptor. But the size of the raptor’s featured in those movies is more representative of – corresponds better to Deinonychus.
This is the skeleton of Deinonychus. Other interesting features – they had ossified tendons like bony rods, so they could hold their tail well off the ground rather stiff as a counter balance to the anterior portion of the body. The arms were big, the hands are almost bigger than the feet, and that’s another characteristic of these raptor dinosaurs. They also had a well developed sternum, much like birds. Some had an external keel, and in birds that keel is the attachment site for their pectoral muscles, their big flight muscles in the flying birds.
Now in the Jurassic Park movies, the raptor dinosaurs, they were portrayed as really vicious, aggressive, intelligent creatures. Now this is one of the most amazing fossils - dinosaur fossils that has ever been found. It was found in rocks about 80 million years old in Mongolia and it shows Velociraptor itself holding onto the head of a ceratopsian dinosaur, and they probably died as a result of a collapsing, may be wet sand dune that collapsed on top of them. You can see here that it looks like the ceratopsian is actually holding onto one of its arms in its jaws. Now, this, the Protoceratops, the ceratopsian in question, would have been a rather slow animal. So thereÂ’s no way it would be able to outrun the raptors. It shows that the raptors had no difficulties or wouldnÂ’t hesitate taking a plant-eating dinosaur who was much bigger than itself.
Now the idea that Ostrom again, he revitalised the idea between a close link between small theropod dinosaurs and birds, in particular the raptor dinosaurs and birds. And that idea grew in popularity amongst palaeontologists working with dinosaurs, and even more so when we started finding a whole range of small raptor dinosaurs in 120 million year old lake deposits in China. Now this is one of the most common raptor dinosaurs found in these Chinese lake deposits – Microraptor. This is the skeleton and not only do we find the skeleton of dinosaurs in these lake deposits, we also find a lot more. Now again, this is Microraptor. That’s the head, this is the arm, that’s a leg, the tail and these are flight feathers. It turns out that almost all the raptors we are finding in these Chinese lake deposits, certainly those that are really well preserved, they were covered in feathers. They had flight feathers as well. You can see it has flight feathers on its leg. It even has feathers at the end of the tail. Most likely it climbed trees and then it could glide maybe from one tree to another, but it appears it also was probably able of some sustained flight, and that was used – like some of the arguments in the 1920s, 1930s and a bit later, why birds couldn’t have been derived from dinosaurs because dinosaurs, they don’t have feathers. Well, now we know that they do. They were covered in feathers.
Not only are we finding feathers in raptor dinosaurs, but also in some of the more, what we call, basal or theropod dinosaurs that are more distantly related to the raptor dinosaurs. But again, some palaeontologists working on birds and some ornithologists, they said “Oh well, yeah, we agree. Some of the raptor dinosaurs, they had feathers, but there are certain skeletal structures in birds that are not present in dinosaurs.” One is the wishbone. The collarbones are fused in birds to form the wishbone. So they said “Well look, we don’t have any wishbones in any dinosaurs.” It didn’t take long for us to start finding wishbones in dinosaurs. Raptor dinosaurs, they had wishbones. So there goes that objection.
But then they pointed out again that, well, “Birds they have a most unique set of lungs.” The way a bird breathes is not like us. We inhale the air in the lungs and then we expel it, like a bellow, in out, in out. The way it works in a bird is quite different. They have an extremely efficient way of getting rid of CO2 and extracting oxygen. Now apart from the lungs – and the lungs in a bird, they’re not squishy like ours. They are quite stiff. Our lungs have little tiny alveoli, dead-end alveoli. You don’t have that in birds at all, and in addition to the lungs, they have several pairs of air sacs. One of them is unpaired, the clavicular air sac. But they have anterior thoracic air-sacs, posterior thoracic air sacs and abdominal air sacs. I’ll show you how it all works.
The way it works when a bird breathes; it inhales air here, but instead of going into the lungs, it goes into the posterior air sacs. So the posterior air sacs expand. They are sucking in air here, but then you have an anterior set of air sacs that also expands at the same time when the bird inhales. So air is going in here, but on the other hand – and then you have the valve-like structure here, where at least it works like a valve because when you dissect a bird you don’t really find a typical valve. So when this anterior air sac, when that expands, it sucks the air out of the lungs. And then when the bird exhales, there is a valve like mechanism here that prevents this air that’s now in the posterior air sac from going out the other way. So when they contract, the anterior air sac and the posterior air sac, that air is now going out here, whereas this air is now going into the lung. So that means that the whole system works like a one-way. Air comes in here and then it goes out there. So there is never any real mixing of air that is enriched now in CO2, carbon dioxide, with oxygen rich air.
For our lungs to work as efficient, if we would have to be able to exhale all the air, and we can’t – we can’t really collapse our lungs – so it is a superior way of extracting oxygen. The interesting thing also about this system is that these air sacs. They have little projections that actually grow into some of the bones, into the vertebrae for example and make them lighter. The clavicular air sac have projection that grows into the wishbone, and the ornithologists, they pointed out “Well, if dinosaurs were birds, shouldn’t they have the same advanced breathing system? Shouldn’t we see evidence in the skeleton indicating these, what we call pneumatization, these holes where part of the air sac had grown into the bone?”
Well, a couple of years ago palaeontologist Paul Sereno and colleagues described the first case of a pneumatized wishbone in a theropod dinosaur. So there we go again. What we thought was absolutely unique character to birds is now present in at least one theropod. ItÂ’s probably present in other theropods as well, but in order to find this structure preserved, the bone has to be exceptionally well preserved. In most cases when we find dinosaur bones, they have lots of minerals encrusting the bones and we might not see all the small foramina. So it partly was a result of an exceptional state of preservation.
So here we have what we thought were absolutely unique characters to birds present in dinosaurs as well. This is by the way the wishbone of one of the goose species, the Magpie Goose.
This particular theropod, Aerosteon, had lots of well pneumatised vertebrae. You can see here the space here where the extensions probably from the cervical air sacs. So actually not really that involved in the actual respiration, and saurischian dinosaurs, they tend to have them all along the vertebral column. But then more importantly is the presence of these holes, these foramina in bones where there really could only be supplied with the extension of the air sacs, from air sacs that are directly involved in the respiration.
So it appears that dinosaurs, they were not these slow, cold-blooded creatures that they were portrayed in the mid 1900s, around 1950 thereabouts. Instead they were highly efficient. The mere fact that many of them were covered in feathers, not only raptors, but other theropods as well, thatÂ’s a good sign of the creature being warm-blooded because that provides an insulation if youÂ’re rather small. Whereas if youÂ’re very big you donÂ’t need really any feathers or much hair for that matter. I mean look at elephants for example.
Now, as a result we now have changed the view on how we view birds from a classification point of view. There are so many characters that link birds to raptor dinosaurs. So it becomes almost ridiculous trying to argue that birds are not closely related to dinosaurs. In fact they are so closely related to dinosaurs, so we now classify them as dinosaurs.
This is just to give you a general idea about how we classify them. Here we have the main division into the ornithischians, the plant-eating dinosaurs, and the saurischians, the meat-eating dinosaurs which also include the plant-eating sauropods. You can see here up at the top we have the penguin, a bird grouped together with the raptor dinosaurs. So it appears that the birds are deeply nested within the dinosaur tree. So that also means that the dinosaurs actually didnÂ’t go extinct at the end of the Cretaceous, 65 million years ago. They survived. We have 10,000 species of dinosaurs living. IsnÂ’t that encouraging?
When we talk about dinosaurs we have to remember that you often find different dinosaurs in the Northern Hemisphere compared to the Southern Hemisphere. The configuration of continents was different back 150 million years ago for example, than it is today. In the Southern Hemisphere all the continents were joined together into a supercontinent called Gondwana. So we find similar dinosaurs in South America and Australia. They could migrate from one continent to another. Maybe that was a dinosaur?
In Australia, we donÂ’t have too many places where you can find dinosaurs. We have two main sites. One is in Victoria, some coastal cliffs where they are excavating lots of dinosaurs, but mostly itÂ’s isolated bones. They havenÂ’t found any complete skeletons of dinosaurs there, but lots of smaller ones, particularly smaller ornithopod dinosaurs in particular.
The other area is in Queensland. There are a couple of sites up there. We have Minmi, the most complete dinosaur ever found in Australia. It belonged to this group, the thyreophorans, the Shield Bearers. Another one Muttaburrasaurus, and as I mentioned, we have a cast of a Muttaburrasaurus skeleton on display in the Diamonds to Dinosaurs gallery. IÂ’m sure you all have visited.
But the main site finding dinosaurs in Australia is a town in central Queensland called Winton. They are excavating dinosaurs in Winton as we speak. Just a couple of years ago they described Australovenator. That’s the most complete meat-eating dinosaur ever found in Australia. It had big – there we are – big claws on the hand, and it would have been may be about five metres in length. And apart from Australovenator they also described two species of large sauropod dinosaurs belonging to a group called the titanosaurs. Diamantinasaurus is one of them. It was a very robust, stocky sauropod, may be 17-18 metres in length and would have been quite heavy, possibly weighing as much 15 or may be 20 tonnes.
The other one, Wintonotitan, obviously named after Winton, is small. ItÂ’s about the same length, but a little bit more gracile, may be not quite as heavy, but still gigantic. Now theyÂ’re finding so many dinosaurs in Winton, so they build a dinosaur museum there. So if you ever go to Winton, check out their museum. I think itÂ’s called Age of the Dinosaurs.
Now what about Western Australia? Well this is actually a photograph of me out at the site near Moora looking for dinosaurs, and I almost look a little bit depressed there as if I haven’t found anything. Now, over the last 100 years we’ve been looking and looking for dinosaur bones in Western Australia and we’ve found five fragmentary bones. That’s it. Five bones. I didn’t find any bones on that day, or the next day for that matter, but I certainly kept trying. When you look for dinosaur bones you don’t want to look in marine sediments that were laid down in the ocean, because you wouldn’t find any dinosaurs there. You want to look – the best type of sediment is what we call floodplain sediments - sediments that were laid down on floodplain, typically during a flooding episode. Maybe dinosaurs drowned trying to cross a river and their carcasses were swept away and ended up may be a point bar in the river and they were covered by sediments. So you want to look at a floodplain sediment obviously from the age of the dinosaur. This is the right type of sediment of the right age, but we didn’t find any.
Here I am again looking into the hillside. This particular outcrop here, thereÂ’s an alternation between sand and fine mud, and that is probably whatÂ’s referred to as a crevasse splay deposit. During a flood episode when you have the strongest flow, you get a lot of sand spread over the river banks and then followed by mud. You tend to get sand and then mud, and that might represent a single flooding episode. I didnÂ’t find any here.
The main reason why we donÂ’t find dinosaur in Australia, apart from the possible fact that I might be totally incompetent when it comes to finding dinosaurs, thatÂ’s possible, is that 140 million years ago Australia started separating from India or the part of India that is now under the Himalayas. So it was just drifting apart. When a continent splits up into two continents, the first thing you get is a rift valley. ThereÂ’s a place in east Africa called the East African Rift Valley, and if you go to Perth, you can actually see the remnants of that rift valley. ThatÂ’s the Darling Fault. ThatÂ’s part of that rift valley, when Western Australia drifted apart from India 140 million years ago.
But what happens now when two continental plates just drift apart is that you donÂ’t get much of what we call uplift. Whereas in the other scenario where two continental plates collide, one of them will be forced underneath the other, and you get the formation of the mountain range. The Andes is a good example where an oceanic plate is forced underneath a continental plate and you get the mountain formation. So that means the whole rock rises up and you get increased erosion and a constant supply of fresh rock. But if part of a continent sits near the sea level for tens of millions of years or hundreds of millions of years, it will be very deeply weathered. ThatÂ’s a problem.
IÂ’m sure there were dinosaur bones here originally but they most likely have been leached by rainwater for example. Rainwater is a bit acidic. Rain picks up CO2 and forms carbonic acid, and it will leach out bones over time. It was a very scenic place. ItÂ’s a real shame I didnÂ’t find any fossils.
On the other hand in April I went on a little trip to Alberta in Canada. This is a fantastic place. ItÂ’s may be 50 kilometres north of a town called Drumheller and this area is called the Dinosaur Provincial Park. IÂ’m sure you can figure out why itÂ’s called Dinosaur Provincial Park. ItÂ’s just full of dinosaur bones. These are the right type of sediments, about 75 million years old, floodplain settlements. You imagine meandering rivers working their way towards the ocean and during flooding episodes, thatÂ’s when you get sediments spread over the floodplain, and may be dinosaurs drowned and you can later find their bones sticking out of the rock.
Now I couldnÂ’t help myself, but I went down into these gullies and started looking for bones, and guess how long it took for me to find a bone? In Western Australia it takes on average 20 years. Anyone? No, it took me 20 minutes. It took me 20 minutes. There it is. ItÂ’s probably part of a leg bone. Yeah, 20 minutes to find a bone, and I was looking in an area where thereÂ’d been a lot of tourists. So itÂ’s been picked out pretty well. In some areas of the parks, there are so many dinosaur bones you have to be careful where you put the foot down, or youÂ’ll step on a dinosaur bone.
IÂ’ve been to similar outcrops in Montana in the US and in some places you can just sit down and start picking up teeth of raptor dinosaurs. One of the best places to look for small dinosaur bones and small dinosaur teeth, is thereÂ’s a particular species of ant that, whenever they build their little ant nest, if there are little fossils they will actually pick up the fossils. So the ant hill might be made up of one quarter of vertebrate fossils from the age of the dinosaurs. So if youÂ’re real mean and sieve the ant hill, the ants get a bit upset, you might find a lot of vertebrate fossils.
Now although we donÂ’t have many dinosaur bones from Western Australia, we have some really good dinosaur footprint sites, well one site, up in the Dampier Peninsula, all the way from a bit south of Broome and for a stretch of almost 100 kilometres, and particularly footprints of sauropod dinosaurs are very common and this image here, you can see a track way of a sauropod dinosaur walking along.
Sauropods, obviously they would have been very large animals, they were very heavy. You can see here where he puts his foot down, itÂ’s so heavy so the layers underneath here have actually buckled. You can see the deformation going down may be half a metre due to the sheer weight of these sauropods. Some sauropods may have weighed as much as 50 metric tonnes, like five or six/seven African bull elephants.
That was the last image I had and I thought this was rather suitable – Kentucky Fried dinosaur. The main message is basically that although it is a tragedy that all the large dinosaurs died out 65 million years ago, we should embrace the fact that we have about 10,000 species of living dinosaurs, and that palaeontologists working on dinosaurs these days, they will almost no exception classify birds without a doubt, as dinosaurs, because all the characters that had been used to differentiate birds from dinosaurs, we are now finding these characters in dinosaurs as well. When you look at many birds, there were quite a few ancient bird groups in the Cretaceous, those birds have now gone extinct, that again show many intermediate stages between a typical dinosaur and a bird dinosaur. For example, they might have a longer tail or may be they had a short tail of modern birds, but they had instead teeth, proper teeth for example. I’ve collected bird teeth myself in rocks 80 million years old in Wyoming, from an ant hill. Yeah, I’m sure they forgive me, the ants.
So basically, that was the last image I have and IÂ’m glad you all came to listen to this and hopefully youÂ’ve learned a bit about dinosaurs, and birds.
Thank you."
nobody here though.. 
