Has The Rise and Fall of the Dinosaurs by Steve Brusatte been sitting on your reading list? Pick up the key ideas in the book with this quick summary. Dinosaurs have long captivated our imagination. There have been many successful films that feature them, from Jurassic Park, to the unforgettable T. Rex fight in Peter Jackson’s King Kong? However, these images we have of the dinosaurs are simply fantasy. How much do you really know about dinosaurs? That’s where Steve Brusatte can help. The history of human life on Earth is only a fraction of that which was populated by the dinosaurs, a fact which really brings to light how quickly everything can vanish, just as it did for the dinosaurs. For almost 200 million years, dinosaurs roamed and ruled the Earth. This was long before humans could even be considered a species. Suddenly, 66 million years ago, they were completely wiped out. People have only fairly recently started to piece together – sometimes quite literally! – facts about them and their environment. Now, thanks to fascinating new research and discoveries, we know more than ever about the history of the dinosaurs – even though some pieces of the puzzle are still missing. Let this book summary take you on a journey. Travel back to the land before humankind: the land of the dinosaurs! In this summary by The Rise and Fall of the Dinosaurs by Steve Brusatte, you’ll learn

• how Disney films like Fantasia and Pinocchio relate to the T. Rex;
• where half of all recent dinosaur fossil discoveries have occurred; and
• why dwarf dinosaurs once called Transylvania home.

The Rise and Fall of the Dinosaurs Key Idea #1: Dinosaurs weren’t the first life to call Earth home, and it’s only because of a cataclysmic event that the dinosaurs were able to dominate.

Most people probably assume that dinosaurs were the first glimpse this planet had of life, lasting right up until their extinction. But, of course, dinosaurs weren’t the first inhabitants of Earth. Around 390 million years ago, life first crawled onto land. Between this time and the end of the Permian Period, which was around 252 million years ago, life on Earth was defined by odd reptiles and mammalian creatures. The Permian Period was brought to an end in one of the largest mass extinctions in history. This extinction began with mass volcanic eruptions of magma. This magma flowed for several hundred thousand years, and maybe even a few million. We have evidence for this disaster from looking at geological records; rock formations from this period show a drastic change in rock type and a complete halt in the presence of fossils. The event was devastating: by the time this volcanic crisis ended, about 90 percent of species was gone. This ultimately lead to the Triassic Period. It wasn’t a complete destruction of all life, though. Tracks from early archosaurs –early reptilian ancestors of dinosaurs – have been discovered, and are thought to be from around 250 million years ago. These archosaurs thrived in this new, magma-filled world, which lead them to divide into two groups: the ancestors of today’s crocodiles, known as the pseudosuchians – whose name means "false crocodiles” – and the avemetatarsalians. The avemetatarsalians evolved into dinosaurs as we know them, and these dinosaurs then split into three groups. These groups were the meat-eating theropods, the plant-eating ornithischiansand, and the long-necked sauropods. These groups didn’t just evolve and survive – they thrived. 230 million years ago, numerous species called what is now Argentina’s Ischigualasto Provincial Park home. A phenomenal amount of fossils have been found in this region over the course of the twentieth century. Because of the hot and humid climate, as well as its tendency to flood, this region is ideal for fossil preservation. Although it took a near-apocalypse for the age of the dinosaurs to begin, the Triassic Age had now truly dawned. From here on, the history of the dinosaurs would be a long evolutionary journey, and there was still quite a long way to go.

The Rise and Fall of the Dinosaurs Key Idea #2: Even though the dinosaurs didn’t start out as the dominant species, they soon established themselves as such by taking advantage of the natural conditions of their ecosystem.

Earth looked nothing like what it does now 230 million years ago. The continents as we know them today sat in a single, giant landmass known as Pangea. The planet also existed in extremely hot temperatures — the poles as temperate as London or San Francisco today. Pangea was often plagued by “megamonsoons”, which divided the supercontinent into different environmental regions. Each environmental sector existed as a blank slate when it came to the climate. The Permian extinction meant that each section would become a fertile breeding ground for all creatures. Nature started to experiment, and before long, huge numbers of mammals, amphibians, and reptiles called Earth their home. Dinosaurs also called this planet home — but they weren’t yet the dominant species. In Ischigualasto, for instance, the dinosaurs were only 10-20% of the population of creatures in the area. And that number might even be fairly high: the author’s own field research in Portugal displayed that the dinosaurs didn’t even populate the hot, equatorial regions of Pangea. Nearby, in Spain and Morocco, the only fossils in the record are those of reptiles and amphibians. Because of this, we’re able to tell that dinosaurs mostly lived in more humid regions of the southern hemisphere, particularly today’s Brazil and India. However, the domain of the dinosaurs didn’t remain this small for long; dinosaurs quickly increased in numbers and spread over the globe. This growth happened for two main reasons. First, around 225 to 215 million years ago, the dominating non-dinosaur herbivores who lived in these humid ecosystems declined in numbers. Scientists haven’t yet found a direct cause for this decline, but because of this, dinosaurs now had far more access to opportunity and resources. This eventually lead to them making up around 30 percent of all species in those regions. Then, around some 215 million years ago, potentially after some more drastic changes to the global climate, dinosaurs were able to migrate north. We know this due to fossil evidence found across the United States, particularly Arizona and New Mexico. There, for instance, the Chinle Formation, a rock sequence formed around 225 to 200 million years ago, teems with fossils from this period. In it, we can see a rich ecosystem of large amphibians and reptiles. But, more importantly, a few smaller meat-eating theropods are preserved there too. After 30 million years, dinosaurs were finally on the incline in their populations, but they were still overshadowed by pseudosuchians – the “false crocodiles” mentioned in book summary one. However, the dinosaurs were about to emerge as the rulers of this vast land.

The Rise and Fall of the Dinosaurs Key Idea #3: Due to their survival of another mass extinction, the dinosaurs were set to become some of the largest animals ever to exist.

Around some 240 million years ago, Pangea began to split up. As it slowly dispersed, the continents as we know them today were being formed in a slow and nearly imperceptible process. And around 201 million years ago, the Triassic Period was brought to a violent end. While Pangea broke apart, magma pooled just beneath the Earth’s crust, eventually breaking through the surface. However, this was no normal volcanic eruption. Lava tsunamis obliterated nearly 3 million square miles of central Pangea. Around 30 percent of all existing species at the time were wiped out. This was no small-scale event, either. The extinction event that brought the Triassic period to a close consisted of four major lava surges, each around 3,000 feet deep, which passed over the Earth. Incredibly, the dinosaurs were the survivors of this disaster. Shown by the fossils we’ve found in recent years, the dinosaurs not only survived the event, but now dominated in the Jurassic Age. The North American seaboard is where much of this information has been found. It consists of a number of rift basins such as the Gettysburg Basin — bowls that were formed when the continent split from northwestern Africa. Studying these basins alongside the patterns of dinosaur migration shows that dinosaur fossils became more abundant and diverse after the volcanic eruptions, however, the pseudosuchians effectively vanish. Paleontologists haven’t yet been able to pinpoint why these two species had such different fates. Why the dinosaurs flourished is still unclear, but flourish they did. This was the age of the sauropods — massive dinosaurs and the biggest animals to ever live on dry land. This includes the familiar Brontosaurus, Diplodocus, and Brachiosaurus,recognizable large dinosaurs with long necks.  The oldest fossils – found on Scotland’s Isle of Skye – have allowed us to see that the first sauropods, who inhabited the area some 170 million years ago grew to be up to 50 feet long. Sauropods were, in fact, so large that when excavators first discovered their fossils in the 1820’s, they mistook them for whale bones. But the size of these sauropods served a purpose. Their long necks allowed them to reach, and therefore consume, larger quantities of food than their neighbors. They came equipped with efficient breathing mechanisms, extremely light skeletons, the ability to expel heat from their bodies, and, of course, their impressive heights, far outreaching (literally) the abilities of other dinosaurs.

The Rise and Fall of the Dinosaurs Key Idea #4: We know a great deal about the Jurassic Period due to geologic processes and mercenary fossil hunters.

Around 150 million years ago, during the Late Jurassic Period, the world was teeming with dinosaurs. We are able to know this due to the extensive fossil record from the time – but why was this the case? One reason is that many different types of dinosaurs called areas close to the water home. This makes a difference because areas like rivers, lakes, and seas are ideal for fossil preservation. These areas are full of sedimentary rocks, which form and protect fossils within their layers, which is where these fossils sit, waiting to be dug up. The Morrison Formation, one of these areas located in the United States, is so rich in fossils that it became the battleground of the Bone Wars. Fossils were found at several locations here in March 1877, which prompted huge numbers of opportunists to rush to the area. These people were trying to get jobs with one of two bitter rivals: Philadelphia's Edward Drinker Cope or Othniel Charles Marsh of Yale University. These two teams discovered some of the most important fossils in history, including the carnivorous Allosaurus, and the long-necked herbivores we discussed earlier: the Brontosaurus, Diplodocus, and Stegosaurus. The fossil record, however, isn’t the only thing that allows us to put together the history of these great creatures. Due to other paleontological discoveries, we are able to have a broader sense of the changes that happened to the world during the Late Jurassic Period. Pangea continued splitting up, but it was only doing so at the rate that fingernails grow. This made it so that the world’s ecosystems were extremely similar. However, around 145 million years ago, at the dawn of the Cretaceous Period, the climate began to gradually change. The world cooled extremely quickly, which caused sea levels to fall and land mass to increase. This means that the general makeup of dinosaur communities was due for a change too. The giant sauropods were extinct within 20 millions years, and in their place, smaller plant-eating ornithischians flourished. Because there were so many of these, it also meant that a large variety of carnivorous theropods were able to thrive on this new food source. One of the most impressive of these theropods was the enormous and terrifying carcharodontosaur. Originating in Africa during the Late Jurassic Period, it then migrated around Pangea, diversifying as the land broke apart. Then, by the early and mid-Cretaceous Periods, it sat at the top of the food chain. To give you a sense of how menacing this dinosaur was, the carcharodontosaurgets its name from the Greek phrase meaning “sharp-toothed lizard.” However, although the carcharodontosaurs might have been incredibly intimidating, another carnivore was about to take the spotlight.

The Rise and Fall of the Dinosaurs Key Idea #5: Although the T-Rex is the most famous and menacing, other members of the tyrannosaur family were just as impressive.

Most people, when asked to name a dinosaur, would name the Tyrannosaurus Rex. But did you know that T. Rex was actually just one member the tyrannosaurfamily? Due to recent discoveries, new information has been found about this fascinating family. In total, 20 new types of tyrannosaur have been discovered all over the globe, from the Gobi Desert to the Arctic Circle. The author even had a hand in identifying the Qianzhousaurus sinensis after a discovery of bones in China in 2010. It even has a cute nickname: Pinocchio Rex! In addition to this one, almost half of all new dinosaur species discovered have been found in China alone. The tyrannosaur family shares a few main characteristics. All of them carnivores with huge heads, the tyrannosaurs had strong athletic bodies and long tails. And, of course, who could forget those comically small and seemingly useless arms? They were a pretty tough family too. Although tyrannosaurs made their first appearance during the mid-Jurassic Period, they were the most dominant during the cretaceous period. Kileskus is the oldest known member of the family discovered to date. Discoveredin Siberia in 2010, it lived around 170 million years ago — about 100 million years before T. Rex. Only about seven or eight feet long, Kileskus would have lived in the shadow of the 30-foot-high Allosaurus and other, even larger carcharodontosaurs. It seems a little strange to put this tiny dinosaur in the same category as the T. Rex, but there are good reasons for doing so. Scientists have been able to identify an evolutionary stepping stone: the Guanlong has characteristics shared by both T. Rex and Kileskus, as well as several other tyrannosaurs. We still aren’t able to discern just how it is or when exactly they grew so large and how they managed to bestride continents. This is due to the poor fossil record from around 110 to 84 million years ago. What we do know is that tyrannosaurs weren’t always the huge size we know them to be, and they once lived among other, larger predators. We also know that they eventually superseded the carcharodontosaurs in North America and Asia. However, by the time the cretaceous period was in full swing, the rule of our well-known king could not be disputed.

The Rise and Fall of the Dinosaurs Key Idea #6: Because of the fossil records we do have, we actually know more about the T-Rex than we do many living animals, and it definitely lives up to it’s terrifying reputation.

One dinosaur remains the most famous after years of discoveries: Tyrannosaurus Rex – whose name literally translates to tyrant lizard king! How did the famous T-Rex gain so much notoriety? The first reason is that we have access to so many T-Rex fossils. This huge amount of research has lead us to know a lot about them and their traits. A young fossil collector named Barnum Brown discovered the first specimens in Montana in 1902. In 1905, they were put on display at the American Museum of Natural History in New York. Brown was later so respected for this discovery that he helped Walt Disney design the dinosaurs in the move Fantasia. To date, over 50 T-Rex skeletons have been discovered, some of which are nearly complete. That’s far more than the information we have about most other dinosaurs. Because of these discoveries, we know now that T. Rex lived around 66 to 68 million years ago, primarily in western North America. The interesting thing, though, is that the T. Rex has been found to be closely related to some species from Asia. Because of this, it’s thought that the T. Rex originated in either China or Mongolia, and migrated across the Bering Land Bridge before heading down through Alaska and Canada to reach North America. While there were other tyrannosaurs living in North America already, they didn’t compare to these new arrivals from Asia. Most people would recognize the T. Rex no matter what, though, and this is primarily because of its absolutely terrifying nature. T. Rex stood at about 42 feet in long and weighed around seven or eight tons. Its mouth was full of razor-sharp teeth. Based on experiments, it’s been proven that the T. Rex was able to bite with the force of 3,000 pounds per tooth. To compare it to modern carnivores, lions can on manage about 940 prounds total. There’s even been an Edmontosaurus tail fossil with a T. Rex tooth wedged in it, meaning the Edmontosaurus must have survived and healed from a failed, but brutal attack. Contrary to what most people think, the T. Rex was actually fairly intelligent compared to other dinosaurs. As CAT scans have shown, its brain was actually quite large compared to its body. Its IQ might have been similar to that of a chimp, and it was certainly far more clever than any dog or cat you might have as a pet. It’s also believed that they were pack hunters. Imagine how terrifying it would’ve been to be confronted with that!

The Rise and Fall of the Dinosaurs Key Idea #7: Although the T. Rex was the king of North America, they weren’t the only dinosaur success story.

1. Rex dominated in North America, but what about the rest of the world? By the end of the Cretaceous period — around 84 to 66 million years ago — Pangea was on its last legs, about to split into the continents as we know them today. Due to continental drift, ecosystems had also begun to change.

This begs the question: What other dinosaurs existed on other continents? Luckily, the author himself has spent time studying fossils in Goiás, Brazil. He was able to find there that carcharodontosaurs was the ruler of this local ecosystem. This was probably due to the fact that tyrannosaurus never migrated that far south, and therefor never took over their domain. It also appears that throughout the southern hemisphere, various types of crocodiles thrived in environments where small and medium sized theropods had failed to materialize. In other parts of the globe, biodiversity among the dinosaurs was able to emerge due to localized circumstances. In the late-nineteenth century, Baron Franz Nopcsa von Felső-Szilvás unearthed various fossils in Transylvania, all of which dating from this same period. They were all miniature versions of species that had been discovered in the rest of the world. This is because this area had once been an island, and it was this island effect that had caused the evolutionary development of these dwarf dinosaurs. Back in North America, although the T. Rex was extremely successful, other species had adapted and thrived in this environment too. A four legged beast with a crown of horns, the Triceratopsremains one of the most iconic and memorable dinosaurs of all time. Herbivorous creatures with evolved beaks at the end of their snout — probably for plucking plants — they would strip plants with their guillotine-like teeth.

1. Rexes probably targeted them for food often. However, due to their size, Triceratops was most likely able to put up a good fight, especially with those giant horns.

Like other dinosaurs, Triceratops likely thrived during this time. Fossils found in Hell Creek, Montana indicate that Triceratops made up 40 percent of the dinosaur population, while the T. Rex only peaked at about 25 percent. It’s become evident that this area was actually the richest ecosystem of dinosaurs discovered to date.

The Rise and Fall of the Dinosaurs Key Idea #8: Birds aren’t simply the descendants of dinosaurs, they are dinosaurs – and their main characteristics are reminiscent of the Jurassic Period.

The myth that birds evolved from dinosaurs isn’t completely correct. While birds did initially evolve fromdinosaurs, they eventually were evolving alongside them.Birds can be thought of as a subgroup of dinosaurs, like how we categorize sauropods or tyrannosaurs. The initial link between birds and dinosaurs came out of the nineteenth century. It took a long time, though, for this idea to be widely accepted as truth. When Charles Darwin published his foundational thoughts on evolutionary theory in 1859, he sparked a rough debate. Darwin’s proponents and his skeptics alike raced to find proof either of evolution as truth or proof that evolution was false. It wasn’t long before convincing evidence was discovered. A "missing link” was found in a Bavarian quarry in 1861. This was a 150-million-year-old fossil of an Archaeopteryx, which seemed to be a creature that was an exact hallway point between bird and reptile. It was Thomas Henry Huxley – the grandfather of famed author Aldous Huxley – who figured out the mystery of this missing link. He was the one who noticed how similar Archaeopteryx and Compsognathus— a small dinosaur that was known from a fossil found in the same area — seemed to be. He was then able to conclude that dinosaurs were the ancient ancestors of birds as we know them today. However, Huxley's theory was soon overshadowed by a Danish theory from the 1920s, which argued that birds and dinosaurs couldn’t possibly be related. They based this idea off of the fact that dinosaurs didn’t have collarbones. Birds have them in the shape of wishbones, which are essentially just fused collarbones. This alternative theory wasn’t debunked until the 1960s when paleontologists uncovered a bird-like fossil in Wyoming. This newly discovered creature seemed unquestionably to be a close cousin of Velociraptor. Because of this, Huxley’s older theory was again unearthed. The final proof was dug up in China in 1996: the fossil for a dinosaur called Sinosauropteryx clearly displayed that it once had feathers. However, feathers aren’t the only connection to dinosaurs birds had during the Late Cretaceous period. A set of fossils from the Gobi Desert showed that a family of dinosaurs had died while trying to protect their nest of eggs. It’s also become clear that feathers didn’t develop simply to initiate flight: it’s far more likely that they developed to provide insulation and protection. It’s important not to forget the role feathers have in attracting mates. We can tell that the feathers of these early birds were brightly colored from pigment analysis, so it’s likely they were used primarily for display. There are also theories that say that different species learned to fly independently of one another, thereafter evolving into the diverse variety of birds we know today. It’s clear, based on fossil records, that birds and dinosaurs coexisted for around 100 million years. Soon though, another catastrophe would befall the planet, one so bad that the word “cataclysmic” can’t even do it justice.

The Rise and Fall of the Dinosaurs Key Idea #9: An impact from space was the final end to the dinosaurs, but some scientists believe they were already on their way out.

Sixty-six million years ago, an asteroid or comet – scientists are unsure which – about the size of Mount Everest smashed into Earth. With a force equivalent to a billion nuclear bombs, it set off a global chain reaction. By the end of the event, 70 percent of allspecies on Earth were extinct, the dinosaurs among them. The geological evidence is clear: never have scientists doubted that a cataclysmic extinction actually happened. Evidence lies in many places, one example being a gorge outside of Gubbio, Italy, where a thin layer of clay separates the fossil-rich Cretaceous Period limestone from the Paleogene Period’s barren limestone. While there isn’t any mystery that an event happened, scientists still aren’t completely certain what actually caused the event. Walter Alvarez, one of the scientists who began to search for answers, set out to determine how long this layer of clay had taken to form. He was going to figure this out by measuring iridium. Iridium is an element falls gradually from space, so by measuring its presence in the clay, Alvarez would be able to calculate how quickly the clay layer had formed. Alvarez found that the amount of iridium in the layer was, quite literally, astronomical. There was no connection that could be made between this layer and the limestone layers that surrounded it, whose formation could be accurately dated. So in 1980, Alvarez hypothesized that the iridium must have been brought from space all at once. This was simply a hypothesis until a 110-mile-wide crater was found in Mexico in the 1990s. Not only was it clearly caused by something from outer space, but it could also be dated to exactly the moment of the formation of that clay layer, thus confirming the theory. However, we need to remember that things weren’t perfect for the dinosaurs in the years leading up to this astronomical end. They also faced problems with climate change and it’s been argued that the dinosaurs were already facing extreme problems. The author himself has gotten involved in trying to discern what was actually happening with the dinosaurs. He analyzed species diversity in the two groups of dinosaurs that were at the bottom of the food chain. This included plant-eaters – horned ceratopsians similar to  Triceratops– and duck-billed dinosaurs. He was able to tell that the diversity of the dinosaurs was indeed declining, however, overall population numbers remained steady. Due to this steady population, it’s clear that they weren’t on the route to extinction at this point. However, a food web declining in diversity can also lead to collapse. Because of this, we may never be able to tell whether this extinction was inevitable, but we do know brought the dinosaurs to their inevitable end. We can still see traces of their dominance due to the few species of birds that survived the apocalypse. Now, the slate was clean, and the Earth was ready for the rise and evolution of humanity.

In Review: The Rise and Fall of the Dinosaurs Book Summary

The key message in this book summary: For some 200 million years, dinosaurs evolved in an ever-changing world, eventually becoming the rulers of the Earth. From movies starring the foreboding T. Rex, to the dinosaur subgroup we still see today – today’s birds – the dinosaurs have left a mysterious and intriguing history that we have been fascinated by for generations.