Our imagination has long been fascinated by dinosaurs. Think of successful movies like Jurassic Park, and who can forget the T. Rex fight in Peter Jackson’s King Kong?
However, these are only imagination. In reality, how much we have information related to dinosaurs? Steve Brusatte can help in this issue. People were here in a fraction of the time that dinosaurs existed. It makes you realize how quickly it can disappear, just as for dinosaurs.
The dinosaurs existed in the world for almost 200 million years before they were destroyed 66 million years ago and ruled the Earth. Then, they were completely disappeared. Over the past few centuries, we have been able to bring together only some of the facts about them and their environment.
Even though some parts are still missing, we know more about dinosaurs with new research and discoveries.
Being dominant is terrifying for dinosaurs because there was life on Earth before them.
According to the common belief, the dominance of the dinosaurs on Earth continued from the first events of life on the planet to their extinction.
Of course, the first inhabitants of Earth were not dinosaurs.
Life crawled onto land for the first time about 390 million years ago. Approximately 252 million years ago, at the end of the Permian Period, strange reptiles and mammals have formed the animal kingdom.
However, the greatest mass extinction of world history was the end of the Permian Period.
The volcanoes began to leak a large amount of magma. It continued to flow for a few hundred thousand years, maybe a few million years. According to the scale of the disaster from geological records, the dramatic change of the rock type and the disappearance of the fossils are characteristics of the structures from this period.
It was devastating: about 90 percent of all species had died when the crisis ended and the Triassic period started.
However, all life did not vanish. Tracks from early archosaurs, the early reptilian ancestors of dinosaurs, showed that they have survived from around 250 million years ago.
They grew up in this new world and then divided into two groups: The ancestors of our modern crocodiles, the pseudosuchians which mean ‘’false crocodiles’’ and the avemetatarsalians.
These avemetatarsalians evolved into dinosaurs and then divided into three groups: The meat-eating theropods, the plant-eating ornithischians, and the long-necked sauropods.
These groups did not just evolve and live. They also grew up.
For instance, in what is now the area of Argentina’s Ischigualasto Provincial Park, there were many species 230 million ago. We have acquired this knowledge through the fossil quantities found there during the 20th century. It was ideal to protect fossils because of the hot and humid climate that caused an occasional flood.
So, it was expected to start the dinosaur age; however, the Triassic Age showed itself. Although it was still a long road, there was a fascinating and diverse evolutionary journey.
Dinosaurs become dominant by taking advantage of environmental conditions in a short time.
Two hundred and thirty million years ago, the Earth was quite different from the planet we know. There was only one land mass known as Pangaea rather than continents. At the same time, the poles were not yet frozen, and they were warm like today’s London or San Francisco. Above all, Pangea was divided into different environmental regions by ‘’mega monsoons’’.
Each of these new environmental provinces was basically a blank slate. They have become fertile breeding grounds for all kinds of creatures with the Permian extinction. Many mammals, amphibians and reptiles were able to call Earth home with the trials of nature.
Of course, there were also dinosaurs, but they only made up around 10 to 20 percent of the ecosystem so their domination was hard.
This is even relatively high: According to the author’s own field research in Portugal, dinosaurs did not live in the hot equator areas of the Pangea.
When we look at the fossil record in Spain and Morocco, we see only reptiles and amphibians. Therefore, it is clear that the dinosaurs in the southern hemisphere, including modern Brazil and India, were in more humid regions.
However, the boundaries of the dinosaurs were not stable. They increased their numbers and spread throughout the world because of two reasons.
The first one is that the number of the non-dinosaur herbivores who dominated these ecosystems started to decline around 225 to 215 million years ago. Why this happened was not exactly explained by the scientist, but this decline provided opportunity and resources to dinosaurs for comprising around 30 percent of species in those areas.
Then, around 215 million years ago, some dinosaurs had an opportunity to migrate northward through Pangea probably due to changes in the climate.
There was evidence for this across the US states of Arizona and New Mexico. For example, a rock sequence formed around 225 to 200 million years ago, the Chinle Formation, is full of fossils in this period which shows a rich ecosystem, full of large amphibians and reptiles. On the other hand, critically, there were a few smaller meat-eating theropods too.
Dinosaurs had a place after 30 million years, but pseudosuchians left them in the shadow.
However, the dinosaurs were about to get their big break.
The dinosaurs diversified to be one of the largest animals ever, and they survived another mass extinction.
Pangea started to be shattered around 240 million years ago. The continents in which we live were formed in a slow and barely perceptible process because of this gradual disintegration. But later, the Triassic Period was severely closed around 201 million years ago.
As Pangaea disintegrated, magma began to gather under the Earth’s crust and finally exploded. However, this was not a normal volcanic eruption. The Tsunamis of lava destroyed the center of Pangea about 3 million square miles. In general, around 30 percent of all available species have died. And this was not a one-time event; in total, four lava waves, each up to 3,000 feet deep, passed through the Earth.
Surprisingly, the dinosaurs resisted this difficulty. The fossil record showed that the dinosaurs simply did not survive. They also dominated the Jurassic Age ecosystem.
If we consider the North America seaboard, it becomes clear. This place has rift basins like the Gettysburg Basin, bowls that were formed when the continent leaves northwest Africa.
You will see that dinosaur fossils were more abundant and diverse after the explosions when you examine these basins in the direction of dinosaur migration. In contrast, the pseudosuchians effectively vanish. The reason why the two groups had different fortunes is not explained surely by paleontologists.
Dinosaurs have evolved but how this happened is a mystery. This was the age of the sauropods and the largest animals ever to have lived on land such as dinosaurs. There is no doubt that you are familiar with the long necks of the Brontosaurus, Diplodocus, and Brachiosaurus.
The oldest fossils showed that the first sauropods which were living in Scotland’s Isle of Skye some 170 million years ago grew about 50 feet in length. The Sauropods were actually very large. When the excavators found their bones in the 1820s, they thought they were whale bones!
However, the size of these sauropods served a purpose. Scientists have suggested that they found and consumed larger quantities of food compared to other dinosaurs thanks to their long necks.
We have too much information related to the Jurassic Period with the help of geological processes and mercenary fossil hunters.
The Late Jurassic Period was full of dinosaurs about 150 million years ago. The vast fossil record has been protected so we have this information. However, why is this case?
For starters, it is important that many species of dinosaurs live near water because rivers, lakes, and seas are ideal places to protect fossils. Layers of sediment build up and become rock and in the process, they form and protect fossils. As a result, these fossils are waiting to be discovered where they sit.
The Morrison Formation is a particular area in the United States and it became the battleground of the Bone Wars because of the richness of fossils.
Many opportunists came to the region in March 1877 because there were fossils at several locations. They wanted to get jobs from one of two rivals: Philadelphia’s Edward Drinker Cope or Othniel Charles Marsh of Yale University.
Some of the most famous dinosaurs of all time, including the carnivorous Allosaurus, are discovered by their teams as well as the long-necked herbivores like the Brontosaurus, Diplodocus, and Stegosaurus.
However, we don’t understand the age of dinosaurs only through fossils. Other paleontological discoveries showed that we have a wider perspective on change in the Late Jurassic Period, too.
Pangea was still separating but its speed was too slow for that time. As a result, ecosystems the world over were similar.
When the Cretaceous Period began around 145 million years ago, change of the climate began. Sea levels started to decrease because of a cold snap and arid conditions. As a result of this, the amount of landmass increased. Of course, the make-up of dinosaurs changed.
Most of the gargantuan sauropods died out in about 20 million years and smaller plant-eating ornithischians grew up in their place. A large variety of carnivorous theropods could hold on to life thanks to the high amount of this new bounty.
The carcharodontosaur, originated in Africa in the Late Jurassic Period, is the most impressive of these theropods. After that, it spread around Pangea by diversifying in the field. Eventually, it settled on top of the food chain by the early -and mid-Cretaceous periods.
It gets its name from Greek for ‘’sharp-toothed lizard’’ and it shows an idea of how threatening it would have been.
However, although carcharodontosaurus was scary, another carnivorous family was waiting to empower them.
The rest of the large tyrantos family was as impressive as the famous and scary T. Rex
If you know one dinosaur, it is most probably the Tyrannosaurus Rex. However, T. Rex was just one member of a whole family of tyrannosaurs.
This impressive family was lightened in the last 15 years with the help of discoveries. In total, 20 new types of tyrannosaur have been found from the Gobi Desert to the Arctic Circle all over the world.
In 2010, the author was involved identification of the Qianzhousaurus sinensis which has a cute nickname ‘’Pinocchio Rex’’ after bones were found in China. Interestingly, around half of all newly discovered dinosaur species are found in China.
These family members have some general characteristics.
They were all carnivores and had huge heads, strong athletic bodies and legs, and long tails. Of course, their comically small and useless arms are not forgettable.
They were also a pretty tough bunch. Tyrannosaurs first emerged during the Jurassic period but were actually at the peak of their dominance during the Cretaceous Period.
In 2010, the oldest member, Kileskus, who lived 170 million years ago and was found to date, was discovered in Siberia. Kileskus lived 100 million years ago from T. Rex.
In 2010, the oldest member, Kileskus, who lived 170 million years ago, was discovered in Siberia. Kileskus lived 100 million years ago from T. Rex. It was about seven or eight feet long so it had to live in the shadow of the Allosaurus who was 30-foot-high and carcharodontosaurs who was even larger.
It might be strange to relate this little dinosaur to giant t rex, but there are good reasons for this: An evolutionary step stone was discovered between them: The Guanlong has common characteristics of T. Rex, Kileskus and several other tyrannosaurs.
However, we don’t know when they grew up and how they used the continents well. That comes from the fact that the fossils records from around 110 to 84 million years ago are weak.
What we know is that tyrannosaurs were once smaller and lived with other larger predators, but eventually replaced the carcharodontosaurs in North America and Asia.
When the Cretaceous Period started, especially the rule of one king was undisputed.
We have more information about T. Rex than many living animals because of fossil records and it deserves its monstrous reputation.
Tyrannosaurus Rex, the tyrant lizard king, is one dinosaur that remains more famous than any other today.
How did it get to such a position of ignominy?
For beginners, we are hardly short of T. Rex fossils. We know quite a lot about them thanks to discoveries.
In 1902, Barnum Brown who was a young fossil collector found the first specimens in Montana. These specimens became accessible to the public in 1905 at the American Museum of Natural History in New York. Brown was respected in later life because he helped Walt Disney for designing the dinosaurs for the film Fantasia.
Since then, over 50 skeletons have been found, some of which are almost complete. That’s far more than most other dinosaurs.
These discoveries provide that T. Rex lived around 66 to 68 million years ago and they completely dominated western North America. However, there is an interesting issue. Some Asian species are related to the T. Rex.
For this reason, we think that T. Rex came from China or Mongolia and then went down from Alaska and Canada and crossed the Bering Land Bridge to reach the new playground. There were already other tyrannosaurs living in here but they did not match for the new Asian arrivals.
Everyone knows T. Rex because he was definitely scary. T. Rex reached a length of about 42 feet and weighed around seven or eight tons and his mouth was full of sharp teeth.
Experiments have shown that T. Rex could bite with a force of about 3,000 pounds per tooth. In contrast, the African lions were in total only 940 pounds. Enchantingly, even an Edmontosaurus tail fossil in which a T. Rex tooth was attached was found. This makes think that Edmontosaurus had survived and recovered after a failed but brutal attack.
T. Rex was also quite intelligent. According to CAT scans, it had a large brain compared to his body. It was thought to have an IQ similar to a chimpanzee and was definitely smarter than any dog or cat held at home.
It has also been suggested that they hunted in packs. Imagine how it would have felt confronting that!
The only evolutionary success of dinosaurs was not T. Rex’s domination of North America
T. Rex had North America to live, but there was no way he could rule the rest of the world. After all, the continents were divided and separated as they are today until the end of the Cretaceous period, about 84-66 million years ago. Moreover, ecosystems have changed due to the continental shift.
This creates the new question: What other dinosaurs were there on other continents?
The author has enough time for examining fossils in Goias, Brazil. He showed that the local ecosystem was actually dominated by the carcharodontosaurs. This was most likely because tyrannosaurs never made it that far south and thus never toppled them from their position of power. This was more likely because the tyrannosaurs never took it that far south, and so they never overthrew them.
Interestingly, in the southern hemisphere, it appears that various species of crocodiles had formed in environments where small to medium sized theropods cannot materialize.
In other places, diversity has emerged thanks to the local conditions. At the end of the nineteenth century, Baron Franz Nopcsa von Felsá-Szilvás found various fossils in and around the land in Transylvania. Although they all dated from this same period, they were all miniature versions of species found in the rest of the world. According to some geological researches, the land was once an island, and it was the island’s effect that enabled the evolutionary development of these dwarf dinosaurs.
Back in North America, there was also another species that had adapted well to the environment as successful as the T. Rex.
The Triceratops was one of the most iconic and memorable dinosaurs of all time because they had slow walking and fancy horns. Presumably, they were herbivores with their beaks at the end of their noses to tear off the plants; then they had teeth that were like a guillotine to quickly strip and slice the plant.
Definitely, they were almost tasty targets for T. Rexes. However, they were so strong and large so they were probably able to fight with T. Rexes, no doubt using their horns.
Like many other dinosaurs, the Triceratops have certainly developed. The fossils found in Hell Creek, Montana, showed Triceratops made up 40 percent of the population, while T. Rex reached about 25 percent. In fact, this region was the richest ecosystem of the dinosaurs we know.
Birds not only evolved from dinosaurs, but they also have the basic characteristics of dinosaurs and Jurassic relics.
It is a common myth that birds evolved from dinosaurs. But that’s not quite right.
Birds evolved from dinosaurs, but then they evolved alongside them. The best thing to do is to see the birds as the subgroup of the dinosaurs, much as sauropods or tyrannosaurs were.
In the nineteenth century, the link between the birds and dinosaurs was found firstly, but it was a long time for appealing and accepting.
In 1859, Charles Darwin published his thoughts about evolutionary theory and it caused irritated debate. Both proponents and skeptics began trying to find evidence for demonstrating or disproving the gradual development of species over time.
Finding convincing evidence did not take a long time. In 1861, a ‘’missing link’’ was found in a Bavarian quarry. An Archaeopteryx, the 150 million-year-old fossil, was a creature which was halfway between a reptile and a bird.
Thomas Henry Huxley, the grandfather of famed author Aldous Huxley, evaluated the similarities between Archaeopteryx and Compsognathus, a small dinosaur that was known thanks to the fossil found in the same area. As a result, he stated that birds had originally descended from dinosaurs.
However, Huxley’s theory was soon discredited. A Danish theory from the 1920s argued that birds and dinosaurs could not relate to each other. After all, although dinosaurs had no collarbones, birds have them in the shape of wishbones that are essentially integrated by collarbones.
The refutation of this alternative theory lasted until the 1960s. Paleontologists discovered a bird-like fossil in Wyoming, which seemed to be certainly the cousin of Velociraptor. As a result, the older theory reappeared.
In 1996, the final evidence was found in China: A fossil belonging to the dinosaur Sinosauropteryx clearly showed that it had feathers.
The feathers were not the only features we have associated with birds to develop in dinosaurs during the Late Cretaceous; fossils in the Gobi Desert clearly show that parent dinosaurs killed while looking at the nests of their eggs.
Also, the feathers were not there initially with the aim of flight. They were probably formed to provide isolation and protection.
On the other hand, the feathers have the role of attracting mates. Apparently, these early wings were very colorful according to pigment analysis, so they were probably used for display. Also, it was thought that how to glide independently from one another is learned by various species and then they evolved into the diverse variety of birds we know today.
The fossil record shows that birds and dinosaurs coexist for nearly 100 million years. However, another catastrophe would befall the Earth – and the word ‘’cataclysmic’’ barely does it justice.
A disastrous effect from space killed dinosaurs, but according to some paleontologists, dinosaurs were already out of the way.
Sixty-six million years ago, an asteroid or comet at the size of Mount Everest – scientists are not sure which one – hit the world. Its force was equivalent to a billion nuclear bombs and set off a global chain reaction. When it was over, 70 percent of all species, including dinosaurs, were extinct on Earth.
The geological evidence is clear enough: There is no doubt related to the fact that a cataclysmic extinction happened. For example, a thin clay layer separates the Cretaceous limestone which is rich in fossils from the barren limestone of the Paleogene Period in a gorge outside of Gubbio, Italy.
However, scientists were confused about what had caused the event.
Walter Alvarez, one of the scientists who began to search for answers, worked for determining how long this layer of clay had taken to form. He supported the idea that the solution could be gotten by measuring iridium.
This element gradually falls from space so Alvarez could calculate how fast the layer formed by measuring its presence in the clay.
To his surprise, the amount of available iridium was literally astronomical. It was found that there was no relation to the amount of iridium in the limestone on both sides of the clay layer. Ultimately in 1980, Alvarez suggested that something must have brought it out of space at once.
It was just a hypothesis until a 110-mile-wide crater was discovered in Mexico in the 1990s. This must have originated from something coming from space, and moreover, it could have turned exactly the right moment. So, the theory was confirmed.
However, it should not be thought that everything was fine for the dinosaurs before the comet smash. Apparently, climate change was a problem and there were already extreme difficulties for the dinosaurs.
What was going on was work to be understood by the author himself. Plant-eaters which are horned ceratopsians similar to Triceratops and duck-billed dinosaurs were analyzed by him for species diversity in the two main dinosaurs groups which are at the bottom of the food chain.
As a result, he proposed that diversity was declining, but the total population remained stable. This showed that they did not become extinct at this stage. On the other hand, a less diverse food web is also more susceptible to collapse.
Therefore, we cannot be sure whether the extinction of the dinosaurs was inevitable. However, we know what really killed them. The traces of their domination still remain thanks to a few species of birds that have survived in the apocalypse.
But the slate was all but wiped clean – the world, once filled with dinosaurs, was now free in the rise of humanity.
Book Review
Dinosaurs have benefited from all the advantage of their changing world to evolve and become the rulers of the Earth for some 200 million years. The legacy and mystique of the dinosaurs have continued from the movies we watch T. Rex to the actual dinosaur subgroup we see every day which is today’s birds.
