The Rise and Fall of the Dinosaurs | Stephen Brusatte

Summary of: The Rise and Fall of the Dinosaurs: A New History of a Lost World
By: Stephen Brusatte

Introduction

Embark on an extraordinary journey through the fascinating world of dinosaurs in our summary of Stephen Brusatte’s ‘The Rise and Fall of the Dinosaurs: A New History of a Lost World’. Delve into riveting tales of these prehistoric giants, exploring their origins, evolution, and eventual fall amidst mass extinction events that shaped the Earth’s history. Uncover the mysteries of archosaurs, the Triassic Period, and the emergence and diversity of dinosaur groups like theropods, ornithischians, and sauropods. Understand how these magnificent creatures dominated ecosystems and discover what led to their downfall.

The Rise of Dinosaurs

Life existed on Earth for nearly 390 million years before dinosaurs appeared. Following a volcanic eruption at the end of the Permian Period, roughly 252 million years ago, the largest mass extinction event in the Earth’s history occurred. Nearly 90 percent of all species perished before the ushering of the Triassic Period, where the early reptilian ancestors of dinosaurs thrived. These early reptiles eventually divided into two groups, avemetatarsalians and pseudosuchians. Avemetatarsalians were the ancestors of dinosaurs and evolved into three groups – theropods, ornithischians, and sauropods. The dinosaur age had begun.

Rise of the Dinosaurs

Two hundred and thirty million years ago, Earth was a vastly different place. With only one landmass, Pangea, and a hot climate, it was divided into different environmental regions by “megamonsoons.” But, after the Permian extinction, creatures quickly filled the diverse and fertile landscape. Dinosaurs made up only a small fraction of the ecosystem but expanded their territory due to a decline in non-dinosaur herbivores and changes in climate. Over time, they multiplied rapidly and eventually became 30% of species in humid regions. Fossil evidence shows the Chinle Formation in the US states of Arizona and New Mexico, which teems with fossils from this period, indicating that the dinosaurs began to assert themselves.

The Rise of Dinosaurs

The book explains how around 201 million years ago, a catastrophic volcanic eruption took place that caused the obliteration of 3 million square miles of central Pangea, killing about 30% of all species. Four lava surges occurred, each up to 3,000 feet deep, passed over the Earth. Even after enduring this extinction event, the dinosaurs managed to survive and dominate the new ecosystems of the Jurassic Age. Their fossils became more abundant and diverse after the eruptions, and the pseudosuchians effectively vanished. The reason for the dinosaurs’ excellent prospects remains a mystery, but it’s speculated that the sauropods’ long necks allowed them to consume larger quantities of food compared to other dinosaurs. Scientists have postulated that their efficient breathing mechanisms, light skeletons, ability to expel excess body heat, and their impressive growth rates meant that they could reach gargantuan heights, far outstripping lesser dinosaurs.

Dinosaurs in the Late Jurassic Period

The Late Jurassic Period was full of various types of dinosaurs close to water bodies, which aided fossil preservation. The Morrison Formation area was a battleground for fossil discovery that led to the discovery of famous dinosaurs such as Allosaurus and Stegosaurus. Paleontological findings reveal that most of the gargantuan sauropods went extinct, and smaller plant-eating ornithischians thrived, allowing a vast variety of carnivorous theropods to survive. The carcharodontosaur dominated the food chain globally, until another carnivore family was ready to take over.

The Late Jurassic Period was a time teeming with different kinds of dinosaurs, primarily because most types of dinosaurs lived near water. Preservation of dinosaur fossils, as we know, happens in places such as rivers, lakes, and seas because layers of sediment build up and become rocks that protect fossils in the process. The vast fossil record proves this fact. One particular area, the Morrison Formation in the United States, is so rich in fossils that it became the battleground of the Bone Wars – a fight for dinosaur fossil discovery.

The Bone Wars in March 1877 led to the discovery of many of the most famous dinosaurs globally, such as Allosaurus, Diplodocus, Stegosaurus, and Brontosaurus. Further paleontological discoveries offer broader insights, piecing together the age of dinosaurs.

Around 145 million years ago, as the Cretaceous Period began, a gradual climate change happened, which eventually altered the dinosaur community’s makeup. Most of the gargantuan sauropods were extinct, within 20 million years, replaced with smaller plant-eating ornithischians. Many carnivorous theropods, such as the carcharodontosaurs, could survive off these plant-eating ornithischians, dominating the food chain before another family of carnivores came to replace them.

The carcharodontosaurs originated in Africa in the Late Jurassic Period, spread worldwide and diversifying as the land broke apart. The carcharodontosaur’s imposing size and ferocious profile topped the food chain by the mid-Cretaceous Period. Despite how terrifying they were, another carnivore family was waiting in the wings to take over from the carcharodontosaurs.

The Mighty Tyrannosaur Family

The T. Rex may be the most famous of the tyrannosaurs, but it’s just one of many. Over the last 15 years, 20 new types of tyrannosaurs have been discovered all over the world. All were carnivorous, with huge heads, strong athletic bodies and legs, and comically small and seemingly useless arms. Although they first appeared in the mid-Jurassic Period, tyrannosaurs hit their dominance peak in the Cretaceous Period. The rule of the T. Rex was undisputed by the time we entered the Cretaceous Period, but we know little about how and when they grew so large and managed to bestride continents. The tyrannosaurs had a long and successful reign, and their lineage is still fascinating researchers to this day.

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